JPH1150145A - Production of low thermal expansion alloy sheet for electronic parts, excellent in segregation inhibiting effect and oxide layer inhibiting effect - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a low thermal expansion alloy sheet for electronic parts, capable of effectively preventing segregation and the occurrence of inferior etching, such as striped irregularity, which causes local deterioration in image visibility, capable of high precision etching, and also capable of inhibiting oxide scale and subscale. SOLUTION: A steel ingot, composed of an Fe-Ni alloy containing 30-50 wt.% Ni or an Fe-Ni-Co alloy containing 20-40% Ni and <=7 wt.% Co and satisfying Ni+Co=27 to 40 wt.% and prepared by the ingoting process, or a slab, composed of the above alloy and prepared by the continuous casting process, is subjected to soaking treatment at >=1200 deg.C heating temp. for >=20 hr in total. After the final soaking, the ingot or the cast slab is slabbed at >=10% draft or forged, followed by 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 which is excellent in a segregation suppressing effect and an oxide layer suppressing effect.

[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 performing high-temperature soaking at a high temperature as in this technique generates oxidized scales and sub-scales on the slab surface, requires much time for slab maintenance, and reduces productivity.

As described above, even if any of the above-mentioned techniques is used, it is impossible to effectively prevent uneven stripes due to etching, such as occurs in an Fe-36% Ni alloy thin plate. Oxide scale and the like are generated by the soaking treatment. And, with the high quality of the image,
Etching defects such as uneven stripes tend to increase, and soaking treatment for improving segregation tends to be higher in temperature and longer. Accompanying this, the generation of oxide scale and the like tends to increase, and measures against the increase in grinder care for preventing surface flaws are required.

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 of manufacturing a low thermal expansion alloy thin plate for electronic components, which enables high-accuracy etching and suppresses oxide scale and subscale.

[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 thin plate, the above-described streak unevenness is caused by Ni segregation. In order to improve Ni segregation, a total heating time of 1200 ° C. or more at a heating temperature of not less than 20 hours or more To reduce the amount of slab care required, and to reduce the amount of slab care required to reduce cracks in the oxide scale and subscale. It has been found that rolling or forging is effective.

FIG. 1 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). It is shown that the higher the heating temperature, the longer the heating time, the smaller the Ni segregation degree.

On the other hand, when the Fe—Ni alloy is oxidized at a high temperature, iron oxide grows in a layer on the surface, and a subscale consisting of a mixed metal / oxide portion and a grain boundary oxide portion grows inside the alloy (Cited Document). Nisaburo Matsuno, Shunichi Nishida: Iron and Steel, Vo
l. 68 (1982) P109-116, Kiyoshi Kusakai, Hiroyuki Toki, Takayoshi Ishiguro, Koji Ooka: Iron and Steel, Vol. 74
(1988) P119-126).

FIG. 2 is a schematic diagram of iron oxide and subscale in the slab. The iron oxide on the surface peels off in the next step of hot rolling, but the sub-scale is embedded in the hot-rolled steel sheet and is scattered in islands, causing a difference in elongation between the alloy and the sub-scale during cold rolling, resulting in surface flaws. Therefore, it is understood that it is necessary to remove the sub-scale by slab care by grinder grinding or pickling.

FIG. 3 shows the relationship between the reduction ratio after soaking and the thickness of the sub-scale. It is shown that the grain boundary oxidized portion extends most inside the steel sheet, but the sub-scale thickness (the thickness of the grain boundary oxidized portion) decreases as the rolling reduction increases. 10 after final soaking
% Or more, the grain boundary oxidized portion extended by the soaking process is bent, and the elongation rate between the metal / oxide mixed portion or the metal portion and the grain boundary oxidized portion is different to cause a crack. And the load of slab care is reduced.

The present invention has been completed on the basis of these findings. First, a steel made of an Fe-Ni-based alloy containing 30 to 50 wt% of Ni and produced by an ingot-making method. The ingot or the slab produced by continuous casting is subjected to a soaking heat treatment at a heating temperature of 1200 ° C. or more for a total of 20 hours or more, and after the final soaking of the steel ingot or slab, 10%
The present invention provides a method for producing a low thermal expansion alloy sheet for electronic components, which is excellent in segregation suppression effect and oxide layer suppression effect, characterized by performing slab rolling or forging at the above reduction ratio, followed by hot rolling and cold rolling. Is what you do.

Second, Ni: 20 to 40 wt%,
Co: contains 7 wt% or less, and Ni + Co is 27 to
40% by weight of a Fe-Ni-Co-based alloy, and a steel ingot ingot by the ingot method or a slab ingot by the continuous casting method at a heating temperature of 1200 ° C or more for a total of 20 hours or more. After the final soaking of the steel ingot or slab, it is subjected to slab rolling or forging at a rolling reduction of 10% or more, followed by hot rolling and cold rolling. It is intended to provide a method for producing a low thermal expansion alloy thin plate for electronic parts which is excellent in electronic components.

[0025]

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%.

[0027] In addition to the above-mentioned elements, the alloy of the present invention contains Si, Mn, B, and so on as long as the effects of the present invention are not impaired.
Although N and O may be contained, Si ≦ 0.07 wt%, M
n ≦ 0.5 wt%, B ≦ 0.02 wt%, N ≦ 0.00
It is desirable to limit the range to 5 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 is concentrated in the surface layer of the sheet during the blackening treatment and hinders 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 then slab (continuously cast) by a continuous casting method or an ingot casting method. Method (in the case of the ingot casting method) or ingot (in the case of the ingot making method). This is a total of 20
Heat treatment under heat treatment condition for more than 10 hours
Rolling or forging with a rolling reduction of at least
20 to 300 mm.

As described above, the soaking of the steel ingot or the slab having the above-mentioned composition at a heating temperature of 1200 ° C. or more for a total of 20 hours or more is performed when the heating temperature of the soaking heat is 1
If the temperature is less than 200 ° C. or the total heating time is less than 20 hours, the diffusion effect of Ni segregation is small, etching defects such as uneven stripes are likely to occur, and the local sharpness of an image is lowered.

In addition, the reason why slab rolling or forging is performed at a rolling reduction of 10% or more after final soaking is that cracks are formed in the oxide scale and sub-scale and these are peeled off, thereby reducing the amount of slab care. That's why. 10%
If the rolling reduction is less than 1, the grain boundary oxidized portion extends long inside the alloy, and the grain boundary oxidized portion is less likely to crack, so that the amount of slab care increases.

Thereafter, heat treatment is performed 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
Annealing at 50 ° C. or more is repeated twice or more to obtain a sheet thickness of 0.10
Produce thin plates of ~ 0.25 mm. 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.

In the present invention, after the final soaking treatment, slab rolling or forging is always performed at a rolling reduction of 10% or more in order to peel off the scale. Regardless of its form, such a function may be provided to slab rolling or forging for shape control after the first soaking. However, after the first soaking, one or more rounds of forging or forging for shape control are performed, followed by a final soaking, and finally a rounding or forging for scale exfoliation. It is preferable to do so.

The present invention is generally applied to an alloy thin plate for an electronic component to be etched. In particular, the present invention is applied to a shadow mask having a hole pitch of 300 μm or less by an etching process requiring high precision etching 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. .

[0035]

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, three 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.

[0036]

[Table 1]

The ingots and slabs produced from these ingots are subjected to a soaking treatment at 1100 to 1300 ° C. for 5 to 60 hours, and thereafter, the ingot is subjected to a soot reduction so that the rolling reduction after the final soaking becomes 10% or more. Rolled or forged. Continue 105
Heat treatment was performed at 0 to 1150 ° C. for 1 to 5 hours, and then 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 700 ° C. or more were performed 2 to 4 times to obtain a thin sheet No. 1 having a thickness of 0.10 to 0.25 mm shown in Table 2. 1-20 were produced. In addition, No. Nos. 1 to 15 are examples of the present invention. 16 to 20 are comparative examples.

These Nos. Table 2 shows the soaking conditions and rolling reduction of the soaking conditions of the steel ingot and the slab when the thin plates of 1 to 20 were manufactured. The depth of the grain boundary oxidized portion, the slab care load, the degree of Ni segregation, and the presence / absence of poor etching were evaluated for thin plates manufactured using these ingots and slabs. Table 3 shows the results.

[0039]

[Table 2]

[0040]

[Table 3]

The etching performance was evaluated by performing a photoetching test using a photomask having an electron beam passing 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, the sample 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. In each of Nos. 16 and 19, streak unevenness occurred due to Ni segregation. In addition, in Comparative Example No. 17, 18,
No. 20, the thickness of the grain boundary oxidized portion was large, and the slab care load was large.

[0043]

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. Be able to
Provided is a method for manufacturing a low thermal expansion alloy for electronic components that can suppress an oxide scale and a subscale. 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 shows a soaking condition of a steel ingot or a slab and an N content in a Fe-36 wt% Ni alloy material (amber material).
The figure which showed the relationship with i segregation degree.

FIG. 2 is a schematic diagram of iron oxide and a subscale in an Fe—Ni alloy slab.

FIG. 3 is a graph showing a relationship between a reduction ratio after soaking of a Fe—Ni alloy slab and a subscale thickness (grain boundary oxidized portion depth).

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Masaki Omura 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Tomohiko Uchino 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Sun (72) Inventor Daisuke Ozaki 1-1-2 Marunouchi, Chiyoda-ku, Tokyo, Japan Nihon Kokan Co., Ltd. (72) Naoichi Yamamura 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan Inside Steel Pipe Co., Ltd.

Claims (2)

[Claims] 1. Fe containing Ni: 30 to 50 wt%
1200 ° C. for a steel ingot formed by an ingot-making method or a slab manufactured by a continuous casting method
A total of 20 hours or more of heat treatment is performed at the above heating temperature, and after the final soaking of the steel ingot or slab, slab rolling or forging is performed at a rolling reduction of 10% or more, followed by hot rolling and cold rolling. A method for producing a low-thermal-expansion alloy sheet for electronic components, which is excellent in segregation suppression effect and oxide layer suppression effect. 2. Ni: 20 to 40 wt%, Co: 7 wt%
% Of Ni + Co is 27 to 40 wt%, and is 1200 ° C. for a steel ingot produced by the ingot-making method or a slab produced by the continuous casting method. Perform a soaking heat treatment at the above heating temperature for a total of 20 hours or more.
A method for producing a low thermal expansion alloy sheet for electronic components having excellent segregation suppressing effect and oxide layer suppressing effect, characterized by performing slab rolling or forging at a rolling reduction of 0% or more, followed by hot rolling and cold rolling. .