JP3856616B2 - Rolled copper foil and method for producing the same - Google Patents

Description

【００２０】
本発明に関わる圧延銅箔は，圧延後の再結晶焼鈍で，I ₍₂₀₀₎／I_{0 (200)}≧40という著しく発達した立方体集合組織が得られている。
一方，比較例のNo.1は圧延前の焼鈍で得られるI ₍₂₀₀₎／I_{0 (200)}値が3を下回るため，また比較例のNo.2は圧延前の焼鈍で得られるI ₍₂₀₀₎／I_{0 (200)}値が10を超えたことにより再結晶粒が異常成長して，その粒径が30μmを超えているため，圧延後の再結晶焼鈍で得られるI ₍₂₀₀₎／I_{0 (200)}値が低下している。比較例のNo.3およびNo.4は，圧延前の焼鈍で得られるI ₍₂₂₀₎／I_{0 (220)}またはI ₍₃₁₁₎／I_{0 (311)}が1を超えているため，圧延後の再結晶焼鈍で得られるI ₍₂₀₀₎／I_{0 (200)}値が低下している。
比較例のNo.5は圧延加工度が93%を下回るため，また，比較例のNo.6は圧延前の焼鈍で得られる結晶粒径が30μmを超えるため，圧延後の再結晶焼鈍で得られるI ₍₂₀₀₎／I_{0 (200)}値が低下している。
【００２１】
図2にI ₍₂₀₀₎／I_{0 (200)}値と屈曲寿命との関係を，データを銅箔の厚みで層別して示す。I ₍₂₀₀₎／I_{0 (200)}値が高くなると，屈曲寿命が長くなることがわかる。なお，銅箔の厚みが薄くなると屈曲寿命が延びているが，曲げ部表面に与えられる歪みが小さくなるためである。
【００２２】
【発明の効果】
圧延銅箔が薄くなると立方体集合組織の発達度が低下し，特に厚みが18μm以下となると，従来のプロセスでは立方体集合組織を所望のレベルまで発達させることが困難になるが本発明方法を採用すると，厚さが18μm以下の銅箔においても，再結晶焼鈍後に，I ₍₂₀₀₎／I_{0 (200)} ≧40のレベルの立方体集合組織を安定して得ることができる。
また，再結晶焼鈍後に立方体集合組織が著しく発達する圧延銅箔は，フレキシブルプリント回路基板用素材として特に好適である。
【図面の簡単な説明】
【図１】屈曲疲労寿命の測定を行うために使用した屈曲試験の説明図である。
【図２】圧延後再結晶した後のＩ(200)／Ｉo(200)と屈曲寿命の関係を示す図である。
【符号の説明】
１．銅箔
２．ねじ
３．振動伝達部材
４．発振駆動体[0001]
[Industrial application fields]
The present invention relates to a method for producing a rolled copper foil in which a cubic texture is remarkably developed when recrystallization annealing is performed. This copper foil is suitable for use as a flexible wiring member such as a flexible printed circuit board that requires high flexibility.
[0002]
[Prior art]
When a copper plate or copper foil produced by rolling is recrystallized and annealed, a cubic texture ((100) [001] orientation) develops. Cubic texture has various effects on various properties of copper.
As advantages of cubic texture is developed, it can be mentioned that the fatigue properties of the low distortion / high cycle (or 10 ⁴ times the fatigue life) is improved. From this viewpoint, in Japanese Patent No. 3009383, a copper foil having a cubic texture is applied to a material of a flexible printed circuit board (hereinafter referred to as FPC) that requires bending fatigue characteristics. In addition, as a measure to develop the cubic texture, (1) the degree of work in final rolling should be 90% or more, and (2) the recrystallized grain size obtained by annealing before final rolling should be adjusted to 5-20μm. Advocated.
[0003]
However, recently, a manufacturing process capable of developing a cubic texture more than ever has been desired. For example, regarding copper foil for FPC,
(1) With the downsizing of the equipment, the bending deformation given to the FPC has become more severe, and the copper foil has been required to have an excellent bending life.
(2) The thickness of copper foil used for FPC has been 35μm in the past, but in recent years, thin ones of 18μm, 12μm and 9μm have been used. When the copper foil becomes thinner, the degree of development of the cube texture decreases even if the copper foil is manufactured by the same process.
Etc. are given as the background.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to provide a method for producing a rolled copper foil in which a cubic texture is remarkably developed when recrystallization annealing is performed.
[0005]
[Means for improving the problem]
The present inventor has intensively studied a manufacturing process in which an extremely developed cubic texture can be stably obtained. In this study, the final rolling degree was set to 93% or more, and the effect of the structure before the final rolling (recrystallized structure obtained by annealing before the final rolling) on the development of the cube texture was examined. As a result, it was found that a more advanced cube texture can be obtained when the cube texture is developed in the recrystallized structure before the final rolling and then rolled and recrystallized and annealed.
[0006]
This is because when copper with a developed cubic texture is rolled, a cube-shaped band structure is formed at a high frequency in the processed structure after rolling, and the cube structure is sharpened starting from this band structure when annealed thereafter. It was speculated that this was due to the formation of an organization (Yoshi Fukutomi, Taichi Kamishiro: Light Metal, Vol. 47, No. 2, pp. 123-130). In order to develop a cube texture of copper foil, it has been conventionally known that a crystal grain size before final rolling is preferably small (Japanese Patent No. 3009383). It was a new finding that the degree of tissue development had an important influence.
[0007]
The present invention has been completed on the basis of the above knowledge, and has optimized a method for producing a rolled copper foil in which a cubic texture is remarkably developed when recrystallization annealing is performed. That is, as Invention 1, by performing recrystallization annealing,
₍₂₀₀₎ / I _{0 (200)} ≧ 40 (I ₍₂₀₀₎ : X-ray diffraction integrated intensity of 200 planes measured on the rolling surface, I _{0 (200)} : X-ray diffraction integration of 200 planes measured with fine powder copper A rolled copper foil having a thickness of 18 μm or less, wherein a cubic texture of (strength) is developed.
[0008]
Invention 2 is a rolled copper foil according to Invention 1, which is a material for a flexible circuit board. Invention 3 is a copper foil manufacturing process in which a tough pitch copper or oxygen-free copper ingot is hot-rolled, then cold-rolled and annealed repeatedly, and finally finished to a predetermined thickness by cold-rolling. (1) at just before annealing in the final cold rolling, an average grain size of the recrystallized grains less 30.mu. m, the rolling surface (200), the (220) diffraction intensity of the (311) and (111) plane,
3 ≦ I ₍₂₀₀₎ / I _{0 (200)} ≦ 10, I ₍₂₂₀₎ / I _{0 (220)} ≦ 1, I ₍₃₁₁₎ / I _{0 (311)} ≦ 1, I ₍₁₁₁₎ / I _{0 (111 )} ≦ 1
(I _(hkl) : X-ray diffraction integrated intensity of (hkl) plane measured on the rolling surface, I _{0 (hkl)} : X-ray diffraction integrated intensity of (hkl) plane measured with fine copper)
(2) The method for producing a rolled copper foil according to invention 1 or 2, wherein cold rolling is performed at a workability of 93% or more in the next final cold rolling.
[0009]
The present invention is effective for a copper foil having a thickness of 18 μm or less. This is because, as described above, when the copper foil becomes thinner, the degree of development of the cube texture decreases, and particularly when the thickness is 18 μm or less, the conventional process (Japanese Patent No. 3009383) develops the cube texture to a desired level. This is because it becomes difficult. When the above method is adopted, a cube texture having a level of I ₍₂₀₀₎ / I _{0 (200)} ≧ 40 can be stably obtained after recrystallization annealing even in a copper foil having a thickness of 18 μm or less.
Moreover, a rolled copper foil in which a cubic texture is remarkably developed after recrystallization annealing is particularly suitable as a material for a flexible printed circuit board.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, the reason why the manufacturing process of the rolled copper foil is defined in the present invention will be described below.
(1) Copper foil material : The main purpose of the present invention is to develop a cubic texture during annealing. Therefore, copper whose recrystallized texture is in a cubic orientation, that is, tough pitch copper (oxygen concentration of 100 to 500 wt ppm). ) And oxygen-free copper (oxygen concentration 10 wt ppm or less). On the other hand, copper containing a large amount of alloy elements is not suitable as a material because the action of the alloy elements hinders the development of cube orientation. However,
[0011]
(1) Tough pitch copper with a small amount of Ag added to adjust the softening temperature to an appropriate range to prevent softening during storage at room temperature (Japanese Patent Application No. 11-9437)
(2) Oxygen-free copper added with a small amount of alloying elements for the purpose of lowering the softening temperature (Japanese Patent No. 1559881, Japanese Patent Publication No. 60-17040, Japanese Patent Publication No. 62-47936, Japanese Patent No. 1849316, Japanese Patent Publication No. 63-140052, JP-A-63-45339, JP-A-1-319640, Japanese Patent No. 2737954)
(3) Oxygen-free copper whose softening temperature has been adjusted to an appropriate range by adjusting the amount of impurities (Japanese Patent Laid-Open Nos. 1-3199641, 1-111932, and Japanese Patent Application No. 11-9332)
Any material can be used. This is because even if alloy elements are contained, the development of the cube texture is not hindered in a very small concentration range (0.1 wt% or less in total).
[0012]
(2) Final rolling workability : The reason why the workability is 93% or more is that if the workability is less than 93%, the cube texture is desired in the annealing after rolling even if the annealing conditions before rolling are adjusted. It is because it does not develop to the level of.
(3) Crystal grain size obtained by annealing before final rolling : The average grain size of recrystallized grains is 30 μm or less. If the crystal grain size exceeds 30 μm, the crystal orientation before rolling is controlled and the final rolling process is performed. This is because even if the degree is 93% or more, the cube texture does not develop to a desired level in annealing after rolling. From the same viewpoint, Patent No. 3009383 regulates the average grain size of recrystallized grains to 20 μm or less. However, if the degree of development of the cube texture is adjusted as described below, an average grain size of 30 μm is allowed. did it.
[0013]
(4) Cubic texture development obtained by annealing before final rolling : The reason why I ₍₂₀₀₎ / I _{0 (200)} is specified to be 3 or more is that when this value is 3 or more, annealing after rolling This is because the cube texture is remarkably developed. On the other hand, when the I ₍₂₀₀₎ / I _{0 (200)} value exceeds 10, the recrystallized grains grow abnormally and the average grain size exceeds 30 μm, and the degree of development of the cube texture during annealing after rolling decreases. Because. The reason why each value of I ₍₂₂₀₎ / I _{0 (220)} , I ₍₃₁₁₎ / I _{0 (311)} and I ₍₁₁₁₎ / I _{0 (111)} is defined as 1 or less is This is because the degree of development of the cube texture during annealing after rolling decreases.
The I / I ₀ values as described above can be obtained by adjusting the previous rolling work degree and the previous annealing conditions. In other words, I ₍₂₀₀₎ / I _{0 (200)} is increased by increasing the rolling degree and decreasing the grain size during annealing, and I ₍₂₂₀₎ / I _{0 (220)} , I ₍₃₁₁₎ / I _{0 (311)} and I ₍₁₁₁₎ / I _{0 (111)} can be lowered.
In addition, the recrystallization annealing defined in (3) and (4) can also be performed by hot rolling.
[0014]
【Example】
The present invention will be described below based on examples.
The experimental materials are tough pitch copper plate (oxygen content 250 ppm) or oxygen-free copper plate (oxygen content 2 ppm) after recrystallization annealing with various crystal grain sizes and orientations, thickness t ₀ mm and width 600 mm. ) Was used. This copper plate was cold-rolled to a thickness of t mm, and then annealed and recrystallized. Here, the working degree d in cold rolling is
d = (t ₀ −t) / t ₀ × 100 (%) (where t ₀ is the thickness before cold rolling)
Given in. Annealing to recrystallize the rolled copper foil was performed by heating the sample for 30 minutes at a temperature 70 ° C higher than the semi-softening temperature. Here, the semi-softening temperature is the annealing temperature when the tensile strength after annealing becomes an intermediate value between the tensile strength after rolling and the tensile strength after complete softening, and the annealing time is 30 minutes. As this temperature was measured first.
[0015]
The crystal grain size of the copper foil before rolling was measured by a cutting method (JISH0501) in a cross section perpendicular to the rolling direction. X-ray diffraction was performed on the copper foil before rolling and the copper foil after recrystallization annealing after rolling. Furthermore, the bending life was evaluated assuming that the copper foil of the present invention was used as an FPC material. Details of the X-ray diffraction and bending test methods are shown below.
[0016]
(1) X-ray diffraction
The X-ray intensity of each surface of (200), (220), (311) and (111) on the rolled surface was determined by X-ray diffraction. Divide this value by the integrated intensity of each surface of finely powdered copper that has been measured in advance, and I ₍₂₀₀₎ / I _{0 (200)} , I ₍₂₂₀₎ / I _{0 (220)} , I ₍₃₁₁₎ / I The values of _{0 (311)} and I ₍₁₁₁₎ / I _{0 (111)} were determined. X-ray diffraction was performed using a Co tube, and the integrated values of peak intensities were (200): 2θ = 57 to 63 °, (220): 2θ = 86 to 91 °, (311): 2θ = 107 to 113 Measured in the range of °, (111): 2θ = 47 to 55 ° (θ is the diffraction angle).
[0017]
(2) Bending test
Assuming that it is used as a copper foil for FPC, after recrystallization annealing of the sample under the above conditions, the bending fatigue life was measured with the apparatus shown in FIG. This device has a structure in which a vibration transmitting member 3 is coupled to an oscillation driver 4, and a copper foil 1 to be tested is fixed to the device at a total of four points including a screw 2 portion indicated by an arrow and a tip portion of 3. Is done. When the vibration part 3 is driven up and down, the intermediate part of the copper foil 1 is bent into a hairpin shape with a predetermined radius of curvature r. In this test, the number of times to break when bending was repeated under the following conditions was obtained. The measurement was performed 5 times for the same material, and the average value was obtained.
Specimen width 12.7 mm, Specimen length: 200 mm, Specimen sampling direction: Specimen length direction is parallel to the rolling direction, Curvature radius r: 2.5 mm, Vibration stroke: 25 mm, Vibration speed : 1500 times / minute [0018]
Table 1 shows the processing history and characteristics of the evaluated samples.
[0019]
[Table 1]

[0020]
The rolled copper foil according to the present invention has a remarkably developed cubic texture of I ₍₂₀₀₎ / I _{0 (200)} ≧ 40 by recrystallization annealing after rolling.
On the other hand, No.1 of the comparative example below _{I (200) / I 0 (} 200) value is 3 obtained by annealing before rolling, and the No.2 of Comparative Example obtained in the annealing before rolling I _{( 200)} / I _{0 (200)} value exceeds 10, the recrystallized grains grow abnormally, and the grain size exceeds 30 μm, so I ₍₂₀₀₎ / I _{0 (200)} value is decreasing. No. 3 and No. 4 in the comparative examples have I ₍₂₂₀₎ / I _{0 (220)} or I ₍₃₁₁₎ / I _{0 (311)} obtained by annealing before rolling exceeding 1, so after rolling The I ₍₂₀₀₎ / I _{0 (200)} value obtained by recrystallization annealing is reduced.
The comparative example No. 5 has a rolling degree of less than 93%, and the comparative example No. 6 has a crystal grain size obtained by annealing before rolling exceeding 30 μm, so it can be obtained by recrystallization annealing after rolling. The I ₍₂₀₀₎ / I _{0 (200)} value is decreased.
[0021]
Figure 2 shows the relationship between the I ₍₂₀₀₎ / I _{0 (200)} value and the bending life, stratified by the copper foil thickness. It can be seen that the flex life increases as the I ₍₂₀₀₎ / I _{0 (200)} value increases. In addition, although the bending life is extended when the thickness of the copper foil is reduced, the strain applied to the surface of the bent portion is reduced.
[0022]
【The invention's effect】
When the rolled copper foil becomes thinner, the degree of development of the cube texture decreases, and particularly when the thickness is 18 μm or less, it becomes difficult to develop the cube texture to a desired level in the conventional process. Even in a copper foil having a thickness of 18 μm or less, a cubic texture with a level of I ₍₂₀₀₎ / I _{0 (200)} ≧ 40 can be stably obtained after recrystallization annealing.
Moreover, a rolled copper foil in which a cubic texture is remarkably developed after recrystallization annealing is particularly suitable as a material for a flexible printed circuit board.
[Brief description of the drawings]
FIG. 1 is an explanatory view of a bending test used for measuring a bending fatigue life.
FIG. 2 is a graph showing the relationship between I (200) / Io (200) and reflex life after recrystallization after rolling.
[Explanation of symbols]
1. 1. Copper foil Screw 3. 3. Vibration transmission member Oscillation driver

Claims (3)

By applying recrystallization annealing, I ₍₂₀₀₎ / I _{0 (200)} ≧ 40 (I ₍₂₀₀₎ : X-ray diffraction integrated intensity of 200 planes measured on the rolled surface, I _{0 (200)} : A rolled copper foil having a thickness of 18 μm or less, characterized in that a cubic texture expressed as (X-ray diffraction integrated intensity of 200 planes measured with fine powdered copper) appears. The rolled copper foil according to claim 1, which is a material for a flexible circuit board. (1) Final cold rolling in the copper foil manufacturing process in which tough pitch copper or oxygen-free copper ingots are hot rolled, then cold rolled and annealed repeatedly, and finally finished to a predetermined thickness by cold rolling. The average grain size of recrystallized grains was 30μ m Hereinafter, the diffraction intensity of the (200), (220), (311) and (111) planes of the rolled surface is
3 ≦ I ₍₂₀₀₎ / I _{0 (200)} ≦ 10, I ₍₂₂₀₎ / I _{0 (220)} ≦ 1, I ₍₃₁₁₎ / I _{0 (311)} ≦ 1, I ₍₁₁₁₎ / I _{0 (111)} ≦ 1
(I _(Hkl) : X-ray diffraction integrated intensity of (hkl) plane measured on rolled surface, I _{0 (hkl)} : X-ray diffraction integrated intensity of (hkl) plane measured with fine powder copper)
(2) The method for producing a rolled copper foil according to claim 1 or 2, wherein cold rolling is performed at a workability of 93% or more in the next final cold rolling.

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