JPH1180839A - Production of low thermal expansion alloy thin sheet for electronic parts excellent in effect of suppressing unevenness in stripe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the method for producing a low thermal expansion alloy thin sheet for electronic parts capable of preventing etching defects such as unevenness in stripes causing local reduction in the visibility of a picture by effectively preventing segregation and capable of etching with high precision. SOLUTION: An ingot composed of an Fe-Ni series alloy contg., by weight, 30 to 50% Ni or an Fe-Ni-Co series alloy contg. 20 to 40% Ni and <=7% Co so as to satisfy 27 to 40% Ni+Co and refined by an ingot making method or a slab refined by a continuous casting method is subjected to soaking treatment at a heating temp. of 1,200 to 1,300 deg.C for >=10 hr, is subjected to blooming at >=30% draft, is furthermore subjected to soaking treatment at a heating temp. of 1,200 to 1,300 deg.C for >=10 hr and is subsequently subjected to hot rolling and cold rolling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low thermal expansion alloy thin plate used for electronic parts subjected to fine etching such as a shadow mask and a lead frame, and more particularly to a high definition shadow mask used for a computer display. The present invention relates to a method for producing a low-thermal-expansion alloy having a favorable effect of suppressing uneven stripes.

[0002]

2. Description of the Related Art Electronic parts such as shadow masks and lead frames are generally used after being subjected to etching.
At this time, there is a demand for a material having a high etching rate and a high etching property which is excellent in the end shape and dimensional accuracy of the hole after etching.

Hereinafter, a shadow mask will be described as an example. Shadow masks are used in television cathode-ray tubes, and are used to provide a specific color tone by precisely irradiating an electron beam emitted from an electron gun to a predetermined position on a phosphor screen supported by a glass body. Has pores. In this case, about 20% of the emitted electron beam passes through the pores and is irradiated on the phosphor, and the remaining 8
Since the crack collides with the shadow mask, the temperature of the shadow mask becomes higher than that of the glass body supporting the phosphor screen. In addition, mild steel sheets such as low-carbon rimmed steel and low-carbon aluminum-killed steel that have been conventionally used as materials for shadow masks have a much larger coefficient of thermal expansion than the glass body that supports the phosphor screen, An electron beam cannot be accurately irradiated to a predetermined position on the phosphor screen due to a positional deviation between them, and the image often becomes unclear.

In order to prevent the image from becoming unclear, attempts have been made to compensate for the above-mentioned misalignment by devising a structure of a support which is a suspension position of the shadow mask, but it is not always sufficient. Absent. Further, in recent years, with the enlargement, higher quality, and higher luminance of television screens, these positional shift problems have become apparent.

[0005] Therefore, as a shadow mask material, Fe-Ni containing 36 wt% Ni, which is a low thermal expansion material, is used.
Use of base alloys is expanding. This alloy has a coefficient of thermal expansion of about 1/10 smaller than that of conventional low carbon steel, and maintains its low expansion property even with electron beam heating on a high-brightness screen. In the shadow mask thus manufactured, color shift due to thermal expansion hardly occurs.

[0006] Fe-Ni alloy thin sheets for shadow masks are usually produced by adjusting an alloy steel ingot by a continuous casting method or an ingot-making method, and then subjecting it to slab rolling, hot rolling, cold rolling and annealing. You. After forming an electron beam passage hole in the alloy thin plate by photo-etching, the shadow mask is manufactured by performing various processes such as annealing, molding, and blackening.

[0007] However, a shadow mask made of a Fe-Ni alloy thin plate has excellent low thermal expansion characteristics, but is poor in etching properties, so that it is difficult to obtain a good hole shape by photoetching. In some cases, poor definition of an image may occur due to poor etching.
Therefore, attempts have been made to improve the etching properties of this Fe—Ni-based alloy thin plate.

For example, in Japanese Patent Publication No. 59-32859, in order to make the hole shape after photoetching uniform over the entire shadow mask, the etching rate is kept constant by preventing the crystal orientation of the etching surface from being irregular. If necessary, the degree of orientation of the {100} crystal plane is improved to 35% or more to achieve improvement.

[0009]

However, in recent years,
With the enlargement of television screens and the expansion of applications to computer displays, the demand for finer images and higher brightness has been further increased, and as a result, holes for passing electron beams have been drilled with higher brightness. Etching has become necessary.

In particular, a high-definition shadow mask used for a computer display mainly has a thickness of 0.1 mm.
5 mm or less material is used, for example, 120 μm in diameter
Are pierced at a pitch of 270 μm, and further fine pitching is being attempted.

[0011] In order to accurately drill such fine holes in the etching surface, the material of the raw material has been improved together with the improvement of the etching technique, but the hole shape caused by the local etching defect still remains. Has occurred, which is one of the causes of the local poor definition of the image.

[0012] This etching defect is observed as fine linear unevenness in the mask portion along the rolling direction of the alloy thin plate, and is called "line unevenness". Most of the stripe unevenness has a width of several tens μm to several mm, and reaches from one side of the mask portion to the opposite side. It has been known that uneven stripes occur due to segregation of Ni or impurities, and several techniques have been proposed for the segregation diffusion treatment by soaking to suppress the uneven stripes.

For example, in Japanese Patent Application Laid-Open No. 2-54744, it is assumed that streak unevenness is caused by segregation of impurity elements such as C, Si, Mn, and Cr, or by a solidified structure at the time of casting. % Of B and heating the slab under specific conditions to prevent segregation, reduce the columnar crystal structure, and suppress streak unevenness. However, in actuality, in a material such as a shadow mask which requires fine etching and low thermal expansion, elements such as C, Si, Mn, and Cr are reduced to 1 wt% in total so as not to deteriorate the characteristics. The amount is reduced as much as possible, and streak unevenness due to such segregation cannot occur, and this technique does not eliminate uneven streak occurring in the Fe-36% Ni alloy thin plate. On the other hand, in the blackening process of the shadow mask, if B exceeds 0.02 wt%, uneven blackening occurs and local color shift occurs.

In Japanese Unexamined Patent Publication No. 60-128253, the cause of the stripe unevenness is the segregation of the Ni component,
By heating the Ni-based alloy steel ingot at a temperature of 850 ° C. to the melting point or less and forging with one or more heats and a cross-sectional reduction rate of 40% or more, to improve Ni segregation,
A method has been proposed in which the shape of the etching hole is improved and uneven stripes are eliminated. However, in a shadow mask for a computer display which needs to form finer etching holes at a high density, the cross-sectional reduction rate is simply reduced by 40%.
% Or more does not eliminate uneven streaks, and because long-term soaking at a high temperature results in oxide scale and sub-scale, which is an alloy layer enriched with Ni, on the slab surface, Requires a lot of time.

According to Japanese Patent Publication No. 6-68128, it is assumed that the cause of uneven stripes is component segregation most dominantly.
Logt ≧ 8.28-6. In a temperature range of 1350 ° C. or less.
It is proposed to perform heat treatment at 09 × 10 ⁻³ T (where t is the retention time (hr) and T is the material temperature). However, simply applying a high temperature for a long time at a high temperature as in this technique cannot effectively eliminate streak unevenness, but merely generates oxidized scale and subscale on the slab surface unnecessarily.

As described above, even if any of the above techniques is used, it is not possible to effectively prevent uneven stripes due to etching, such as occurs in an Fe-36% Ni alloy thin plate. With the development, the etching failure such as stripe unevenness tends to increase, and the soaking temperature for improving segregation tends to be higher in temperature and longer.

The present invention has been made in view of the above circumstances, and can effectively prevent segregation and prevent etching defects such as uneven stripes which locally reduce the sharpness of an image. It is another object of the present invention to provide a method for producing a low thermal expansion alloy thin plate for electronic components that can be etched with high precision.

[0018]

Means for Solving the Problems The present inventors have proposed Fe-N
As a result of various studies on the etching properties of the i-type low thermal expansion alloy sheet, the above-described streak unevenness is caused by Ni segregation, and in order to improve Ni segregation without generating scale, an ingot ingot is required. Or one continuous cast slab
Perform soaking at a heating temperature of 200 to 1300 ° C. for 10 hours or more, and after slab rolling at a rolling reduction of 30% or more,
It has been found that it is necessary to perform soaking at a heating temperature of 200 to 1300 ° C. for 10 hours or more.

The solidification structure of the Fe—Ni alloy differs depending on the solidification temperature. When the forging temperature is high, a columnar crystal structure is formed.
At low temperatures, an equiaxed crystal structure develops (Yashima, Fujii, Moriya: Nisshin Steel Engineering Reports, Vol. 55 (1986) 10).

When a large ingot or slab of 1 ton or more is melted by ingot casting or continuous casting, a casting time of several hours is required. In general, solidification conditions are selected so as to obtain a columnar crystal structure of high-temperature casting.

FIG. 1 schematically shows the solidification structure of an Fe—Ni alloy. The columnar structure is composed of Fe-enriched resin and N
It consists of i-enriched trees and is formed first in the early stage of solidification.
Secondary dendrite and 2 formed from primary dendrite
The next dendrite is present.

FIG. 2 is a diagram showing the relationship between the soaking condition of a steel ingot or a slab and the degree of Ni segregation therein in a Fe-36 wt% Ni alloy material (amber material) slab.
It has been shown that the higher the heating temperature is, the longer the heating time is, the smaller the Ni segregation degree becomes, and from the viewpoint of segregation reduction,
A higher temperature and longer time soak is desirable.

On the other hand, when the Fe—Ni alloy is oxidized at a high temperature, iron oxide grows in layers on the surface, and a sub-scale composed of a mixed metal / oxide portion and a grain boundary oxidized portion easily grows inside the alloy ( References Nisaburo Matsuno, Shunichi Nishikida: Iron and Steel, Vol. 68 (1982) P109-116, Kiyoshi Kusakai, Hiroyuki Toki, Takayoshi Ishiguro, Koji Ooka: Iron and Steel, Vo
l. 74 (1988) P119-126). For this reason,
It is not preferable to perform the high-temperature treatment unnecessarily from the viewpoint of reducing the sub-scale. Further, from the viewpoint of energy saving, it is necessary to perform soaking at a lower temperature.

FIG. 3 shows the dendrite arm spacing and 1300
4 schematically shows the relationship with the degree of Ni segregation after soaking at 40 ° C. for 40 hours. If the dendrite arm spacing is as large as 1000 μm even after high temperature and long time soaking,
Although the Ni enriched portion (Ni positive segregation) decreases, the concentration of the Ni negative segregation portion having a low Ni concentration does not increase. On the other hand, when the interval between the dendrite arms is as small as 300 μm, it is shown that not only the Ni positive segregation portion decreases but also the Ni concentration in the Ni negative segregation portion increases and approaches the average concentration.

FIG. 4 is a graph showing the relationship between the reduction rate before soaking and the degree of Ni segregation when soaking at 1200 ° C. for 20 hours. In this figure, when the reduction is not applied before the soaking, the Ni positive segregation is reduced, but there is no effect on the improvement of the Ni negative segregation. It is shown that not only positive segregation but also Ni negative segregation are improved.

Performing soaking after narrowing the dendrite arm spacing is effective in improving the Ni negative segregation as well. However, as a measure for industrially narrowing the dendrite arm spacing, there is a method of slab-rolling. There are reduction and forging, which are effective in narrowing the interval between the secondary dendrite arms in FIG. However, when a reduction is applied in the plate thickness direction, the interval between the primary dendrite arms does not become narrow, and conversely, the primary dendrite arms are crushed to increase the width of the primary dendrite arms, and at the same time, the intervals between the primary dendrite arms become uneven. On the other hand, applying a rolling reduction in the width direction before soaking to reduce the primary dendrite arm interval narrows the product width and deteriorates productivity. 1
In order to improve the segregation of Ni in the next dendrite, it is necessary to perform a soaking treatment before the reduction.

That is, to prevent Ni segregation without unnecessarily heating the steel ingot or slab to a high temperature,
It is necessary to effectively diffuse both the primary dendrite and the secondary dendrite to eliminate the Ni segregation of both the primary dendrite and the secondary dendrite. Further, it is necessary to perform a soaking heat treatment thereafter. Specifically, the first soaking treatment improves the segregation of the primary dendrite and the secondary dendrite, and in the subsequent bulk rolling, the spacing between the secondary dendrite arms is reduced to reduce the diffusion distance. Thereby, segregation (negative segregation) of secondary dendrite is mainly improved.

The present invention has been made based on such findings, and firstly, a steel made of an Fe-Ni-based alloy containing 30 to 50 wt% of Ni and melted by an ingot-making method. The soaking process is performed on the ingot or the slab produced by the continuous casting method at a heating temperature of 1200 to 1300 ° C. for 10 hours or more, after slab rolling at a rolling reduction of 30% or more, and further heating at 1200 to 1300 ° C. A method for producing a low-thermal-expansion alloy sheet for electronic components, which is excellent in the effect of suppressing uneven stripes, characterized by performing soaking at a temperature of 10 hours or more, followed by hot rolling and cold rolling. .

Second, Ni: 20 to 40 wt%, Co:
7 wt% or less, and Ni + Co is 27 to 40 w
% of an Fe-Ni-Co-based alloy which is ingot by the ingot casting method or a slab produced by the continuous casting method at a heating temperature of 1200 to 1300 ° C for 10 hours or more. Heat-treating, after slab rolling at a rolling reduction of 30% or more, further performing soaking heat treatment at a heating temperature of 1200 to 1300 ° C. for 10 hours or more, and then performing hot rolling and cold rolling. An object of the present invention is to provide a method for producing a low-thermal-expansion alloy thin plate for electronic components, which is excellent in suppressing streak unevenness.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. In the present invention, in order to obtain a sufficiently low thermal expansion property so as not to cause a dimensional change or a positional shift that deteriorates the performance of an electronic component, Fe containing 30 to 45 wt% of Ni is used.
-Use a Ni-based alloy. By using such an alloy, the average coefficient of thermal expansion from room temperature to 100 ° C. is 2.0 × 10
Low thermal expansion of ^-6 / ° C or less is realized.

In another embodiment of the present invention, 7w
An Fe-Ni-Co alloy to which t or less Co is added is used. In this case, Ni: 20 to 40 wt%, Co:
7 wt% or less, and Ni + Co is 27 to 40 w
t%. By using an alloy having such a composition, the same low thermal expansion property as that of the above-described Fe—Ni-based alloy can be obtained. If the Co content exceeds 7 wt%, the etching property is remarkably reduced. Therefore, the upper limit of the Co content is set to 7 wt%.

The alloy used in the present invention may include, in addition to the above elements, S as long as the effects of the present invention are not impaired.
i, Mn, B, N, and O, but Si ≦ 0.
07 wt%, Mn ≦ 0.5 wt%, B ≦ 0.02 wt
%, N ≦ 0.005 wt%, and O ≦ 0.002 wt%.

Of these elements, Si can be used as a deoxidizing element for molten steel. However, if it is present in excess, it will be concentrated in the surface layer of the sheet during the blackening treatment and hinder the formation of a homogeneous black oxide film. It is desirably 0.07 wt% or less. Mn is useful for ensuring good hot workability, but when present excessively, it lowers the etching property, and in the blackening treatment, it concentrates on the surface layer of the plate, hindering the formation of a uniform and black oxide film. Therefore, the content is desirably 0.5 wt% or less. B has the effect of improving hot workability and suppressing scale formation. However, if B is excessively present, it is concentrated on the surface layer of the plate during the blackening treatment and inhibits the formation of a uniform black oxide film. It is desirable to make the following. Since N causes deterioration of press workability and etching property, it is preferable to set N to 0.005 wt% or less. O inhibits the growth of crystal grains during softening annealing before pressing and degrades the press formability. Therefore, the content of O is preferably 0.002 wt% or less.

In order to obtain a low-thermal-expansion alloy sheet having the above-mentioned composition, in the present invention, first, an alloy having the above-mentioned composition is melted in a converter or an electric furnace, and slab (continuous casting) is performed by a continuous casting method or an ingot-forming method. Method (in the case of the ingot casting method) or ingot (in the case of the ingot making method). 1200 to 1300 ° C
For the first time under conditions of 10 hours or more, followed by slab rolling at a rolling reduction of 30% or more.
A second soaking treatment is performed at 00 to 1300 ° C. for 10 hours or more.

If the temperature is less than 1200 ° C. or less than 10 hours, the diffusion effect of Ni segregation is small, and streak unevenness is likely to occur. On the other hand, when the temperature exceeds 1300 ° C., adverse effects such as scale formation become more significant. If the slab rolling between two soaking treatments is less than 30%, the effect of reducing the secondary dendrite arm spacing will be reduced.

After the second soaking, it is preferable to perform slab rolling at a rolling reduction of 10% or more. Although the grain boundary oxidized portion extends inside the steel sheet, the subscale thickness (thickness of the grain boundary oxidized portion) decreases as the rolling reduction increases. After final soaking 1
By applying a reduction of 0% or more, the grain boundary oxidized portion extended by the soaking treatment is bent, and the metal / oxide mixed portion or the elongation rate between the metal portion and the grain boundary oxidized portion is different to cause a crack. It is easy to crack, and the load of slab care for removing scale generated by soaking is reduced.

The slab having a thickness of 120 to 300 mm is subjected to a heat treatment at 1050 to 1250 ° C. for 30 minutes or more, and a hot-rolled steel sheet having a thickness of 2 to 3 mm is obtained by hot rolling. About this hot rolled steel sheet, cold rolling and 7
Anneal at 50 ° C or more, and plate thickness 0.10 to 0.25m
m is manufactured. At this time, the cumulative draft from the steel ingot to the thin plate is 99.9% or more. As a result, the desired low thermal expansion alloy thin plate for electronic components can be obtained.

The present invention is generally applied to an alloy thin plate for an electronic component to be etched. Particularly, the present invention is applied to a shadow mask having a hole pitch of 300 μm or less by etching with high precision and low thermal expansion. It is suitable as a method for producing a material. In the present invention, the shadow mask made of a Fe-Ni-based or Fe-Ni-Co-based alloy thin plate having a low thermal expansion characteristic has a small displacement due to thermal expansion, so that an image of a cathode ray tube using the same is sharper. .

[0039]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the alloy thin plate of the present invention is used as a material for a shadow mask will be described below. Table 1 shows the chemical composition of the steel used in this example. Here, four types A to D, which can obtain low thermal expansion characteristics, blackening properties and press moldability required as a material for a shadow mask, were melted.

[0040]

[Table 1]

The ingot and slab obtained by melting these steels are subjected to a first soaking heat treatment at 1150 to 1320 ° C. for 5 to 40 hours, followed by 20 to 75% cracking and rolling. Second soaking heat treatment 1150-13
The test was performed at 00 ° C. for 10 to 40 hours. Thereafter, hot rolling was performed to obtain a hot-rolled steel sheet having a thickness of 2.0 to 4.0 mm. Further, cold rolling and annealing at a temperature of 800 ° C. or more were performed to obtain a thin plate No. 1 having a thickness of 0.10 to 0.25 mm shown in Table 2. 1 to 1
9 was produced. In addition, No. Nos. 1 to 15 are examples of the present invention. 16 to 19 are comparative examples.

These Nos. Table 2 shows the soaking conditions and rolling reductions of steel ingots and slabs when the thin plates 1 to 19 were manufactured. About the thin plate manufactured using these steel ingots and slabs, Ni segregation degree and the presence or absence of poor etching,
The slab care load was evaluated. Table 3 shows the results.

[0043]

[Table 2]

[0044]

[Table 3]

The etching property was evaluated by performing a photoetching drilling test using a photomask having an electron beam passage hole diameter of 110 μmφ and a hole pitch of 250 μm. Presence and processing accuracy were determined. The photoetching at this time was performed under the conditions of spraying an aqueous solution of ferric chloride having a solution temperature of 60 ° C. and a concentration of 47 Baume at a spray pressure of 2.0 kgf / cm ² . Whether there is an etching defect
It was determined by visual observation using transmitted light and reflected light using a one-way light source.

As shown in Table 3, No. 1 of the present invention was used.
In Nos. 1 to 15, slab care load was small, and a low thermal expansion alloy thin plate with minute uneven streaks was obtained. On the other hand, in Comparative Example No. The thickness of the 18 grain boundary oxidized portion was large, and the slab care load was large.

[0047]

As described above, according to the present invention,
Prevents etching defects such as uneven stripes by using a Fe-Ni-based alloy or Fe-Ni-Co-based alloy of a specific composition as a raw material and defining the soaking conditions and the rolling reduction after the final soaking in a predetermined range. A method for producing a low thermal expansion alloy for an electronic component is provided. The low-thermal-expansion alloy thin plate for electronic components manufactured by the method of the present invention is particularly suitable as a material for a shadow mask used for a computer display requiring high-precision processing.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a solidification structure (columnar crystal) structure of an Fe—Ni alloy.

FIG. 2 is a graph showing the relationship between soaking conditions and the degree of Ni segregation.

FIG. 3 is a diagram showing a relationship between Ni diffusion and dendrite arm spacing.

FIG. 4 is a graph showing a relationship between a rolling reduction before soaking and a Ni segregation degree.

Continuing from the front page (72) Inventor Daisuke Ozaki 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Tomohiko Uchino 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Stock Within the company (72) Inventor Akira Yamamoto 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Naoichi Yamamura 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. Inside

Claims (2)

[Claims] 1. Fe containing Ni: 30 to 50 wt%
-Made of a Ni-based alloy, 1200 to slab ingot produced by the ingot method or slab produced by the continuous casting method.
A soaking heat treatment at a heating temperature of 1300 ° C. for 10 hours or more is performed, and after slab rolling at a rolling reduction of 30% or more, a further 1200
A method for producing a low-thermal-expansion alloy sheet for electronic parts having an excellent effect of suppressing streak unevenness, comprising performing soaking at a heating temperature of 1300 ° C. for at least 10 hours, followed by hot rolling and cold rolling. 2. Ni: 20 to 40 wt%, Co: 7 wt%
% Of Ni + Co and 27 to 40% by weight of a Fe-Ni-Co-based alloy, which is 1200 to 200% for a steel ingot produced by the ingot casting method or a slab produced by the continuous casting method. Perform a soaking heat treatment at a heating temperature of 1300 ° C. for 10 hours or more, perform slab rolling at a rolling reduction of 30% or more, further perform a soaking heat treatment at a heating temperature of 1200 to 1300 ° C. for 10 hours or more, and then perform hot rolling and A method for producing a low-thermal-expansion alloy sheet for electronic components, which is excellent in an effect of suppressing streak unevenness, characterized by performing cold rolling.