JP2001137995A - Method of manufacturing low heat expansion alloy this sheet excellent in etching property and thin sheet for shadow mask and shadow mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an Fe-Ni base or an Fe-Ni-Co base alloy thin sheet excellent in an etching property and to obtain the thin sheet for shadow mask and the shadow mask excellent in various characteristics. SOLUTION: In the manufacturing method of a low heat expansion alloy thin sheet of the Fe-Ni base containing 30-50 mass % Ni or Fe-Ni-Co base containing <=7 mass % Co and 27-40 mass % Ni+Co, when a laminar solidified steel ingot, in which an angle formed between a substantial solidified direction and a dendrite growing direction is adjusted to >=50 deg., desirably >=70 deg. in the acute angle side, is bloomed, a bloom-forging is applied so that the perpendicular direction to the substantial solidified direction is made to the main spread- forging direction, and further, a hot-rolling and a cold-rolling of the same direction, are applied. When the laminar solidified steel ingot is bloomed, firstly, the forging is applied so that the angle between the substantial solidified direction and the dendrite growing direction becomes 50-90 deg., desirably 70-90 deg., and successively, the bloom-forging can be applied so that the perpendicular direction to the substantial solidified direction is made to the main spreading direction.

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 sheet for a shadow mask, a lead frame, or the like, which is subjected to fine etching.

[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
It is an object to provide a method for producing an e-Ni-based or Fe-Ni-Co-based alloy thin plate.

[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. It has been found that extending in a direction perpendicular to the direction is effective for improving the etching property.

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 thin plate, when agglomerating a 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, Low thermal expansion with excellent etching properties characterized by performing forging and forging so that the direction perpendicular to the substantial solidification direction is the main elongation direction, and then performing hot rolling and cold rolling in the same direction. This is a method for producing an alloy thin plate. Preferably, 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.

Further, Ni: 30 to 50% by mass%
Or Fe-Ni-Co containing Co: 7% or less and (Ni + Co) being 27 to 40%
In the method for producing a low-thermal-expansion alloy thin sheet, when an ingot is solidified, the angle between the substantial solidification direction and the dendrite growth direction is 50 to 90 °, preferably 7 °.
0-90 °, followed by slab forging so that the direction perpendicular to the substantial solidification direction is the main drawing direction, and hot rolling and cold rolling in the same direction This is a method for producing a low thermal expansion alloy thin plate having excellent etching properties, characterized by performing the following.

Further, in addition to the above-mentioned invention, there is further provided a method for producing a low thermal expansion alloy sheet excellent in 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.

[0009]

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.

The present inventors have investigated the mechanism of poor etching 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.

First, the inventors of the present invention have performed plastic working (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 can be 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 extension direction, and in addition hot rolling in the same direction,
If cold rolling is performed, local microsegregation sites are remarkably small in the manufactured thin plate structure, which is an optimum condition for improving etching unevenness.

As described above, in the method for producing an alloy sheet according to the present invention, it is important to adjust the direction of dendrite growth 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 the angle between the substantial solidification direction and the dendrite growth direction is adjusted to 50 ° or more on the acute angle side, the solidified solidified steel ingot is substantially ingot. This is a method for producing an alloy sheet in which slab forging is performed so that the direction perpendicular to the solidification direction is the main drawing direction, and hot rolling and cold rolling are performed in the same direction. Preferably, the angle between the substantial solidification direction and the dendrite growth direction is adjusted to 70 ° or more on the acute angle side.

In this case, the effect of the expansion of the dendrite works effectively, particularly by extending the substantial solidification direction to the width of the final thin plate, that is, micro segregation on the rolled surface of the final thin plate. Can be homogenized over its entirety. Thereby, a further improvement in the etching property can be achieved.

The laminated solidified steel ingot used in the present invention includes, for example, VAR (vacuum arc remelting method), ESR (electroslag remelting method), PAR (plasma arc remelting method), and EBR (electron beam remelting method). 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.

[0017] The effects of the present invention can be accurately achieved by adjusting the angle between the substantial solidification method and the dendrite growth direction of these laminated solidified steel ingots at a site where the solidified structure is stable. 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.

According to the present invention, in order to efficiently expand the dendrite in the cast structure, the forging is performed so that the direction perpendicular to the substantial solidification direction of the laminated solidified steel ingot is set as the main expansion direction. However, it is effective for further improving the etching property to adopt a method of pre-optimizing the dendrite growth direction in the laminated solidified steel ingot before performing the elongation in the direction.

That is, first, forging (for example, upsetting) is performed on the laminated solidified steel ingot at the time of ingot, so that the angle between the substantial solidification direction and the dendrite growth direction is substantially perpendicular. This is a method of performing lumping forging so that the direction perpendicular to the substantial solidification direction is the main extension direction. The dendrite in the cast structure can be deformed into layers by this forging beforehand, and the interval 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.

More specifically, as shown in FIG. 2, when the laminated solidified steel ingot is divided, first, forging is performed so that the angle between the substantial solidification direction and the dendrite growth direction is 50 to 90 °. Subsequently, a method for producing an alloy thin plate is performed in which forging is performed in such a manner that a direction perpendicular to the substantial solidification direction is set as a main drawing direction, and hot rolling and cold rolling are performed in the same direction. Preferably, the angle between the substantial solidification direction and the dendrite growth direction is adjusted to 70 to 90 °. In this case, the effect of narrowing the dendrite spacing works effectively, especially by extending the substantial solidification direction to the width of the final sheet, that is, the size of the micro-segregation on the rolling surface of the final sheet. Can be reduced more effectively. Thereby, a further improvement in the etching property can be achieved.

In this case, it is preferable that the angle between the substantial solidification method of the laminated solidified steel ingot and the growth direction of the dendrite, which is adjusted in advance, is a portion where the solidified structure is stable. Specifically, as shown in FIG. 2, the intermediate portion along the substantial solidification direction in the state before expansion after the above adjustment, and a half of the middle (radial) direction from the outer periphery of the intermediate portion. Part.

In addition, in the case of the present invention, a 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) step 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 agglomeration of the present invention, the dendrite structure in the steel ingot before the agglomeration forging is adjusted to be small in advance, so that the unit of segregation can be reduced and the segregation line 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 manufacturing 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 characteristic 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 manufactured by the manufacturing 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.

[0028]

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 performing forging forging such that the direction perpendicular to the substantial solidification direction in these ingots is set as the extending direction, the substantial solidification direction and the dendrite growth direction of the ingot prepared under the same conditions are determined in advance. Was measured. The measurement site is an intermediate portion along the substantial solidification direction of the steel ingot, and is a site halfway in the radial direction from the outer periphery of the intermediate portion (see FIG. 1).

Then, the prepared steel ingot was subjected to slab forging in the above-mentioned drawing direction, and hot-rolled and cold-rolled in the same direction to finish into an alloy thin plate, and its etching property was evaluated.
In the above elongation, two conditions are set so that the substantial solidification direction of the steel ingot becomes the thickness of the final thin plate, and the substantial solidification direction of the steel ingot becomes the width of the final thin plate. It was set (see FIG. 1).

In addition, for a part of the steel ingot having a predetermined angle θ, upsetting forging is performed after the pre-upsetting forging is performed so that the angle between the substantial solidification direction and the dendrite growth direction is substantially a right angle. The spreading was performed (see FIG. 2), or a diffusion heat treatment at 1200 ° C. was performed after the forging. The comparative example is a laminated solidified steel ingot in which the angle θ formed by the substantial solidification direction and the dendrite growth direction is 40 °, and the substantial solidification direction is equal to the thickness of the final thin plate (see the above description). Stretching condition), which is stretched in a direction perpendicular to the substantial solidification direction.

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 which affects 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.

[0033]

[Table 1]

As is apparent from Table 1, it is understood that the thin plate manufactured by the manufacturing method satisfying the present invention has a small degree of segregation and a small size of the segregation unevenness. 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 understood that segregation is further reduced in the case of pre-upsetting forging before the above-mentioned spreading, or in the case of performing diffusion heat treatment after lumping forging, and the etching property is improved. In addition, it can be seen that considering the stretching conditions according to the width and thickness of the final thin plate is also effective for improving the etching property.

[0035]

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.

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[Procedure amendment]

[Submission date] November 16, 1999 (1999.11.
16)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction contents]

[0017] The effect of the present invention is achieved in that the angle between the substantial solidification direction and the dendrite growth direction of these laminated solidified steel ingots is adjusted at a site where the solidified structure is stable. 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.

Claims (7)

[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 ingoting a laminated solidified steel ingot, forging and forging so that the direction perpendicular to the substantial solidification direction is the main drawing direction, and further performing hot rolling and cold rolling in the same direction A method for producing a low thermal expansion alloy sheet having excellent etching properties, characterized by the following. 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. An F containing 30 to 50% of Ni by mass%.
e-Ni or Co: contains 7% or less (Ni + C
In the method for producing a Fe—Ni—Co-based low-thermal-expansion alloy sheet in which o) is 27 to 40%, when the laminated solidified steel ingot is massed, firstly, the angle between the substantial solidification direction and the dendrite growth direction. Is forged so as to be 50 to 90 °, followed by slab forging so that the direction perpendicular to the substantial solidification direction is the main drawing direction, and further hot rolling and cold rolling in the same direction. A method for producing a low-thermal-expansion alloy sheet excellent in etching properties, characterized by rolling. 4. When slicing a laminated solidified steel ingot, first, the angle between the substantial solidification direction and the dendrite growth direction is 7 mm.
The method for producing a low thermal expansion alloy sheet having excellent etching properties according to claim 3, wherein the forging is performed so as to be 0 to 90 °. 5. The production of a low thermal expansion alloy sheet excellent in etching properties according to claim 1, wherein diffusion heat treatment is performed before or after or before or after slab forging or hot rolling. Method. 6. A thin plate for a shadow mask, produced by the method for producing a low thermal expansion alloy thin plate according to claim 1. 7. A shadow mask, wherein an electron beam passage hole is formed in the thin plate for a shadow mask according to claim 6 by etching.