JP2008106312A - Rolled copper foil, and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide rolled copper foil having flexing properties more excellent than those of the conventional one for coping with the request of higher flexing properties to the flexible wiring member of a flexible printed circuit board or the like following the progress of the miniaturization, the higher mountability, the higher performance of electronic components, and to provide its production method. <P>SOLUTION: The rolled copper foil subjected to recrystallization annealing after a final cold rolling stage, as the result obtained by X-ray diffraction pole figure measurement based on a rolled plane, has a crystal grain oriented state where the plane orientation degree Δβ in the ä111}<SB>Cu</SB>plane to the ä200}<SB>Cu</SB>plane in the copper crystals is ≤10°, and also, the ratio between the standardized average intensity[a] of the ä111}<SB>Cu</SB>plane diffraction peak by β scanning in α=35° of X-ray diffraction pole figure measurement and the standardized average intensity [b] by β scanning in α=74° satisfies [a]/[b]≥3. The rolled copper foil is produced by controlling the total working degree in the final cold rolling stage before recrystallization annealing to ≥94%, and controlling the working degree per pass to 15 to 50%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a rolled copper foil, and more particularly to a rolled copper foil having excellent bending characteristics suitable for a flexible wiring member such as a flexible printed wiring board and a method for producing the same.

  A flexible printed circuit board (hereinafter referred to as FPC) has a high degree of freedom in mounting form on an electronic device or the like because of its thin thickness and excellent flexibility. For this reason, at present, folding parts of foldable mobile phones, movable parts such as digital cameras and printer heads, and disk-related equipment such as HDD (Hard Disk Drive), DVD (Digital Versatile Disc), CD (Compact Disk), etc. FPC is widely used for wiring of movable parts.

  As the FPC conductor, pure copper foil or copper alloy foil (hereinafter simply referred to as “copper foil”) subjected to various surface treatments is generally used. Copper foils are roughly classified into electrolytic copper foils and rolled copper foils depending on the manufacturing method. Since FPC is used as a wiring material for a portion that can repeatedly move as described above, excellent bending characteristics (for example, bending characteristics of 100 million times or more) are required, and rolled copper foil is used as copper foil. Many.

  In general, a rolled copper foil is obtained by subjecting an ingot of tough pitch copper (JIS H3100 C1100) or oxygen-free copper (JIS H3100 C1020) as a raw material to hot rolling, and then cold rolling and intermediate annealing to a predetermined thickness. It is manufactured by repeatedly applying. The thickness required for the rolled copper foil for FPC is usually 50 μm or less, but recently, it tends to be further thinned to dozens of μm or less.

  The manufacturing process of FPC is roughly as follows: “Process for forming CCL (Copper Claded Laminate) by bonding a copper foil for FPC and a base film (base material) made of a resin such as polyimide” (CCL process), The process includes a process of forming a circuit wiring on the CCL by a technique such as etching, and a process of performing a surface treatment for protecting the wiring on the circuit. In the CCL process, after laminating the copper foil and the substrate via an adhesive, the adhesive was cured and adhered by heat treatment (three-layer CCL), and the surface treatment was performed without using the adhesive. There are two types of methods in which a copper foil is directly bonded to a substrate and then integrated by heating and pressing (two-layer CCL).

  Here, in the manufacturing process of the FPC, a copper foil that has been cold-rolled (hardened by work hardening) is often used from the viewpoint of ease of manufacturing. When the copper foil is in an annealed (softened) state, the copper foil is likely to be deformed (for example, stretched, wrinkled, broken, etc.) when it is cut or laminated with the base material. It is.

  On the other hand, the bending characteristics of the copper foil are remarkably improved as compared to the rolling process finish by performing recrystallization annealing. Therefore, a manufacturing method that also serves as recrystallization annealing of the copper foil in the heat treatment for bringing the base material and the copper foil into close contact and integration in the above-described CCL process is generally selected. In addition, the heat treatment conditions at this time are 1 to 60 minutes (typically 30 minutes at 200 ° C.) at 180 to 300 ° C., and the copper foil is tempered to a recrystallized structure.

In order to improve the bending characteristics of the FPC, it is effective to increase the bending characteristics of the rolled copper foil as the material. In general, it is known that the bending characteristics of a copper foil after recrystallization annealing improve as the cubic texture develops. Note that “cubic texture development” generally referred to only means that the occupancy of the {200} _Cu surface is high (for example, 85% or more) on the rolled surface.

Conventionally, as a rolled copper foil with excellent bending properties, the method of developing the cube texture by increasing the final rolling degree (for example, 90% or more) and the degree of development of the cube texture after recrystallization annealing are specified. Copper foil (for example, the strength of the (200) plane determined by X-ray diffraction of the rolled surface is greater than 20 times the strength of the (200) plane determined by powder X-ray diffraction), penetration in the thickness direction of the copper foil plate Copper foil with a specified proportion of crystal grains (for example, 40% or more in cross-sectional area ratio), copper foil whose softening temperature is controlled by adding a trace amount of additive elements (for example, controlled to a semi-softening temperature of 120 to 150 ° C.), twin Copper foil with a defined crystal boundary length (for example, a twin boundary exceeding 5 μm in length has a total length of 20 mm or less per 1 mm ² area), a copper foil with a recrystallized structure controlled by addition of a trace amount of added elements (for example Sn is added in an amount of 0.01 to 0.2% by mass. The average crystal grain size is controlled to 5 μm or less and the maximum crystal grain size is controlled to 15 μm or less) (for example, see Patent Documents 1 to 7).
Japanese Patent No. 3009383 JP 2006-117777 A JP 2000-212661 A JP 2000-256765 A JP 2001-323354 A JP 2001-262296 A JP 2005-68484 A

  However, in recent years, with the progress of downsizing, high integration (high density mounting), high performance, and the like of electronic devices, demands for higher bending characteristics than ever are increasing for FPCs. Since the bending characteristics of the FPC are substantially determined by that of the copper foil, it is essential to further improve the bending characteristics of the copper foil in order to satisfy the requirements.

  Accordingly, an object of the present invention is to provide a rolled copper foil that is suitable for a flexible wiring member such as a flexible printed wiring board (FPC) and has bending characteristics superior to those of the conventional art. Furthermore, it is providing the manufacturing method which can manufacture stably the rolled copper foil which has the bending characteristic superior to the past.

  The inventors of the present invention have conducted detailed metallographic studies on the formation of a cubic texture by recrystallization annealing in rolled copper foils, so that the grain orientation state before recrystallization annealing, the grain orientation state after recrystallization annealing, and the bending characteristics The present invention was completed based on the elucidation of a specific correlation between the two.

In order to achieve the above object, the present invention provides a rolled copper foil that has been subjected to recrystallization annealing after the final cold rolling step, and is a result obtained by X-ray diffraction pole figure measurement based on the rolled surface. of {200} plane orientation degree Δβ of {111} _Cu plane to the _Cu surface is 10 ° or less, and wherein by β scanning in the alpha = 35 ° in X-ray diffraction pole figure measurement {111} _Cu plane diffraction peak A ratio of [a] / [b] ≧ 3 between the normalized average intensity [a] of [a] and the normalized average intensity [b] of the {111} _Cu plane diffraction peak by β scanning at α = 74 ° Provided is a rolled copper foil characterized by having an orientation state.

Further, in order to achieve the above object, the present invention provides a rolled copper foil subjected to recrystallization annealing after the final cold rolling step according to the present invention, and obtained by X-ray diffraction 2θ / θ measurement on the rolled surface. results for a 90% or higher {200} _Cu plane of the diffraction peak of the copper crystals, and the results obtained by X-ray diffraction rocking curve measurement of the {200} _Cu plane, half width Δθ of the diffraction peak Is a rolled copper foil characterized by being 10 ° or less.

Further, in order to achieve the above object, the present invention provides a result obtained by X-ray diffraction pole figure measurement based on the rolled surface in the rolled copper foil after the final cold rolling step and before recrystallization annealing. When the normalized average intensity of {111} _Cu plane diffraction peaks obtained by β scanning at an α angle is plotted, the normalized average intensity in the range of the α angle of 35 to 75 ° is not stepped. Alternatively, the present invention provides a rolled copper foil characterized by having a grain orientation state in which only one maximum region exists.

  Moreover, in order to achieve the above-mentioned object, the present invention is a copper alloy containing 0.001 to 0.009% by mass of Sn as the rolled copper foil according to the present invention, with the balance being Cu and inevitable impurities. The featured rolled copper foil is provided.

  Further, in order to achieve the above object, the present invention provides a rolled copper foil subjected to recrystallization annealing after the final cold rolling process according to the present invention, and the average grain size of the recrystallized grains observed on the rolling surface. A rolled copper foil having a diameter of 40 μm or more is provided.

Further, in order to achieve the above object, the present invention is a result obtained by X-ray diffraction pole figure measurement based on the rolling surface in the rolled copper foil after the final cold rolling process and before recrystallization annealing, When the normalized average intensity of the {111} _Cu surface diffraction peak obtained by β scanning at an angle is plotted, the normalized average intensity in the range of the α angle of 35 to 75 ° is not stepped, or A method for producing a rolled copper foil having substantially only one maximum region, wherein the total degree of work in the final cold rolling step before recrystallization annealing is 94% or more, and the degree of work per pass Is controlled to 15 to 50%, and the manufacturing method of the rolled copper foil characterized by the above-mentioned is provided.

  Further, the present invention is a method for producing a rolled copper foil according to the present invention described above in order to achieve the above object, and in the final cold rolling step before recrystallization annealing, the “degree of processing in the first pass” ≧ “working degree in the second pass” ≧ “working degree in the third pass” and the working degree after the third pass is controlled to 15 to 25%. A manufacturing method is provided.

  ADVANTAGE OF THE INVENTION According to this invention, it is suitable for flexible wiring members, such as a flexible printed wiring board (FPC), and can provide the rolled copper foil which has the bending characteristic superior to the past. Moreover, the manufacturing method which manufactures stably the rolled copper foil which has the bending characteristic superior to the past can be provided.

A schematic diagram showing main crystal planes of a copper crystal related to the present invention is shown in FIG. Since the crystal structure of copper is cubic, each crystal plane and plane direction have the following relationship.
The angle between the {111} _Cu surface and the {100} _Cu surface is 55 °,
The angle between the {111} _Cu surface and the {110} _Cu surface is 35 °,
The angle between the {111} _Cu surface and the {112} _Cu surface is 90 °,
The {111} _Cu plane and the <112> _Cu direction are parallel.
In addition, {} represents a surface and <> represents a surface direction.

  FIG. 2 is a schematic diagram showing the relationship among incident X-rays, detectors, samples, and scanning axes in X-ray diffraction (hereinafter sometimes referred to as XRD). Hereafter, the evaluation method regarding the crystal grain orientation state of the rolled copper foil by XRD is demonstrated using FIG. Note that the three scanning axes in FIG. 2 are generally called a sample axis, an α axis having a θ axis, and a β axis being an in-plane rotation axis. Further, all X-ray diffraction in the present invention is based on Cu Kα rays.

  A measurement method in which a sample and a detector are scanned with respect to incident X-rays along the θ axis, the scanning angle of the sample is scanned with θ, and the scanning angle of the detector is scanned with 2θ is called 2θ / θ measurement. By measuring 2θ / θ, it is possible to evaluate which crystal plane is dominant (occupancy ratio on the rolled surface) on the sample surface (rolled surface in the present invention) of the rolled copper foil that is a polycrystalline body.

Focusing on a certain diffractive surface {hkl} _Cu , the rocking curve is a measurement method that scans only the sample with the θ-axis relative to the 2θ value of the focused {hkl} _Cu surface (with the detector scanning angle 2θ fixed) This is called measurement. If the half width of the {hkl} _Cu plane peak by this measurement is defined as Δθ, the orientation degree of the {hkl} _Cu plane in the direction perpendicular to the rolling plane can be evaluated by Δθ. At this time, it can be said that the smaller the value of Δθ, the better the crystal orientation in the direction perpendicular to the rolling surface. In other words, since the crystal structure of copper is cubic, it can be considered that Δθ represents how much the cube is inclined with respect to the direction perpendicular to the rolling surface.

Focusing on a certain diffractive surface {hkl} _Cu , α-axis scanning is performed in steps for the 2θ value of the focused {hkl} _Cu surface (the detector scan angle 2θ is fixed), and each α value is On the other hand, a measurement method in which the sample is scanned on the β axis (in-plane rotation (rotation) from 0 to 360 °) is called pole figure measurement. By this measurement, it is possible to evaluate the degree to which the focused {hkl} _Cu surface is inclined from the vertical direction of the rolling surface.

  In the XRD pole figure measurement of the present invention, the direction perpendicular to the sample surface is defined as α = 90 °, which is used as a measurement reference. In addition, the pole figure measurement includes a reflection method (α = 15 to 90 °) and a transmission method (α = 0 to 15 °). The pole figure measurement in the present invention is performed using the reflection method (α = 15 to 90 °). ) Only.

One of evaluation methods using the characteristics of pole figure measurement is in-plane orientation measurement. This is because when the angle between the {hkl} _Cu plane of interest and the crystal plane {h'k'l '} _Cu geometrically corresponding to the {hkl} _Cu plane is α ′, “α = 90− Scan the α axis so that it becomes “α ′” (tilt the sample), and fix the sample to the β axis with respect to the 2θ value of the {h′k′l ′} _Cu surface (fixing the scanning angle 2θ of the detector) This is a measurement method of scanning (in-plane rotation (rotation) from 0 to 360 °). If the average half-value width of the {h'k'l '} _Cu surface peak by this measurement is defined as Δβ, the degree of orientation in the biaxial direction of the {h'k'l'} _Cu surface in the rolling plane is evaluated by Δβ. it can. At this time, it can be said that the smaller the value of Δβ, the better the crystal orientation in the in-roll direction. In other words, it can be considered that Δβ represents how much the cube is rotating in the rolling plane (deviation from the “grid eye” shape).

[First embodiment of the present invention]
(In-plane orientation measurement)
The rolled copper foil in the present embodiment has a {111} _Cu surface having a 55 ° positional relationship with respect to the {200} _Cu surface of the cubic texture in a state where recrystallization annealing is performed after the final cold rolling step. A half width measured by XRD in-plane orientation measurement is 10 ° or less.

FIG. 3 shows that in the rolled copper foil according to the present embodiment, 55 ° with respect to the {200} _Cu surface of the rolled surface after the final cold rolling step (α = It is an example of the result of measuring the XRD in-plane orientation of the {111} _Cu plane having a positional relationship of 35 °). As apparent from FIG. 3, four peaks, that is, four-fold symmetry diffraction peaks appear (when the rolling direction is β = 0 °, the center of each peak is, for example, β≈45 °. , 135 °, 225 °, and 315 °). If the cubic texture is developed (for example, if the {200} _Cu surface of the recrystallized grains occupies about 90% or more of the rolled surface), the four peaks are hardly detected except for the four peaks. Further, Δβ by in-plane orientation measurement of the {111} _Cu plane is 10 ° or less (average of four peaks). This result shows that the {111} _Cu plane is a rolled copper foil that is well oriented in the in-roll direction (having a good degree of grain orientation).

On the other hand, if Δβ of the {111} _Cu surface exceeds 10 °, bending characteristics higher than conventional cannot be obtained. Therefore, Δβ is set to 10 ° or less. More desirably, it is 9.5 ° or less, and further desirably 9 ° or less.

Since the {200} _Cu plane and the {100} _Cu plane are parallel, the angle between the {200} _Cu plane and the {111} _Cu plane is naturally 55 ° (see FIG. 1).

(Ratio of normalized average intensity)
In addition, the rolled copper foil in the present embodiment is the state obtained by β scanning at α = 35 ° of X-ray diffraction pole figure measurement based on the rolled surface in a state where recrystallization annealing is performed after the final cold rolling step. the ratio of the {111} normalized average intensity [a] and alpha = the by β scanning at 74 ° {111} _Cu plane normalized average intensity of the diffraction peak of the _Cu surface diffraction peak [b] is, [a] / [b ] ≧ 3.

Here, the normalized average intensity _RC is a count number obtained by averaging predetermined {hkl} _Cu diffraction peak intensities by β-axis scanning (in-plane rotation axis scanning) at each α angle in XRD pole figure measurement. , And can be calculated by the following formula (refer to the following document for details). The normalization calculation is usually performed by a computer.
R _C = I _C / I _std
here,
I _C : Correction intensity (background correction, absorption correction)
I _std : strength for normalization obtained by calculation.
(Literature name) “RAD system application software texture analysis program instruction manual (manual number: MJ201RE)”, Rigaku Corporation, p. 22-23.
(Literature name) “CN9258E101 RINT2000 Series Application Software Positive Point Manual (manual number: MJ10102A01)” Rigaku Corporation, p. 8-10.

  The reason why the XRD peak intensity is standardized and used is that the comparison can be made without the influence of the difference in the condition setting such as the tube voltage and tube current at the time of XRD measurement (substantially the device dependence. Disappear).

On the other hand, the {111} normalized average intensity of alpha = 35 ° in the XRD pole figure measurement of the _Cu surface [a] for {200} _Cu plane of the rolled surface, normalized average intensity of alpha = 74 ° to the [b] is Each has the following meaning.

As described above, the angle of the {111} _Cu plane to the {200} _Cu plane of the rolled surface is so geometrically is 55 °, the α = 35 ° (= 90 ° -55 °). The normalized average intensity [a] is the diffraction intensity of the {111} _Cu surface corresponding to the {200} _Cu surface of the rolled surface. In other words, it means the normalized diffraction intensity of the {200} _Cu surface on the rolled surface.

Similarly, since the angle formed between the {200} _Cu plane of the rolled surface and the {111} _Cu plane with respect to the twin region of the {200} _Cu plane is geometrically 16 °, α = 74 ° (= 90 ° -16 °). The normalized average intensity [b] is the diffraction intensity of the {111} _Cu surface corresponding to the twin region of the {200} _Cu surface of the rolled surface. In other words, it means the normalized diffraction intensity for the twin region of the {200} _Cu plane on the rolled surface.

Therefore, [a] / [b] means the normalized diffraction intensity ratio between the {200} _Cu plane, which is a cubic texture in the rolled surface, and the twin crystal region.

FIG. 4 is obtained by XRD pole figure measurement of {111} _Cu plane with reference to the rolled surface in the rolled copper foil according to the present embodiment in a state where recrystallization annealing is performed after the final cold rolling step. It is an example of a result. As is clear from FIG. 4, the ratio of the normalized average intensity [a] of the {111} _Cu surface at α = 35 ° and the normalized average intensity [b] at α = 74 ° is [a] / [b] ≧ 3. This result indicates that {200} in the cube texture _Cu surface is mainly a rolled copper foil twin tissues (twin region) with less {200} _Cu plane.

  On the other hand, when the ratio of the normalized average strength is [a] / [b] <3, it is not possible to obtain a bending characteristic higher than the conventional one. Therefore, [a] / [b] ≧ 3. [A] / [b] ≧ 3.5 is more preferable, and [a] / [b] ≧ 4 is more preferable.

[Second Embodiment of the Present Invention]
(2θ / θ measurement)
In the rolled copper foil in the present embodiment, the rolled surface is strongly oriented to the {200} _Cu surface of the recrystallized grains in a state where recrystallization annealing is performed after the final cold rolling step, and the occupation ratio is It is characterized by being 90% or more.

FIG. 5 shows an example of the result of X-ray diffraction 2θ / θ measurement performed on the rolled surface in the rolled copper foil according to the present embodiment in a state where recrystallization annealing was performed after the final cold rolling step. It is. As is clear from FIG. 5, the rolled surface is strongly oriented to the {200} _Cu surface of the recrystallized grains, and the occupation ratio is 90% or more. This indicates that the rolled copper foil has developed a cubic texture.

On the other hand, if the occupancy ratio of the {200} _Cu surface is less than 90%, higher bending characteristics than the conventional one cannot be obtained. Therefore, the occupation ratio is 90% or more. More desirably, it is 92% or more, and more desirably 94% or more.

The occupation ratio was defined as follows.
Occupancy (%) = [I _{{200} Cu} / (I _{{111} Cu} + I _{{200} Cu} + I _{{220} Cu} + I _{{311} Cu} )] × 100
here,
I _{{200} Cu} : {200} Diffraction peak intensity on _Cu surface
I _{{111} Cu} : Diffraction peak intensity of {111} _Cu surface
I _{{220} Cu} : {220} Diffraction peak intensity of _Cu plane
I _{{311} Cu} : {311} The diffraction peak intensity on the _Cu surface.

(Rocking curve measurement)
In addition, the rolled copper foil in the present embodiment has a half width measured by rocking curve measurement of {200} _Cu surface which is strongly oriented on the rolled surface in a state where recrystallization annealing is performed after the final cold rolling step. It is 10 degrees or less.

In the present invention, focused on the diffraction line of the {200} _Cu plane of recrystallized grains account for more than 90% of the rolling surface as described above, to assess the grain orientation degree Δθ of {200} _Cu plane. FIG. 6 shows the result of XRD rocking curve measurement of {200} _Cu surface with respect to the rolled surface in the rolled copper foil according to the present embodiment in a state where recrystallization annealing was performed after the final cold rolling step. This is an example. As is apparent from FIG. 6, Δθ obtained by measuring the rocking curve of the {200} _Cu surface is 10 ° or less. This result indicates that the {200} _Cu surface is a rolled copper foil that is well oriented in the direction perpendicular to the rolled surface (having a good degree of grain orientation).

On the other hand, if Δθ of the {200} _Cu surface exceeds 10 °, bending characteristics higher than conventional cannot be obtained. Therefore, Δθ is set to 10 ° or less. More desirably, it is 9.5 ° or less, and further desirably 9 ° or less.

The crystal grain orientation states so far are summarized. The rolled copper foil according to the embodiment of the present invention is a cube having a {111} _Cu surface with a good in-roll orientation, a {200} _Cu surface with a good vertical orientation on the rolling surface, and an occupation ratio of 90% or more. When considering the texture, it can be said that the copper cubic crystals have a three-dimensionally well-aligned crystal structure.

(Mechanism for high bending properties)
Below, the mechanism of the high bending characteristic of the rolled copper foil which concerns on embodiment of this invention is demonstrated.

  When stress is applied to the metal crystal, dislocations easily move along the slip plane of the crystal, but the crystal grain boundary is generally an obstacle to the movement of dislocations. In a rolled copper foil that is a polycrystalline body, when dislocations accumulate at a grain boundary or the like due to a bending motion, cracks are likely to occur at the accumulation location, which is considered to cause so-called metal fatigue. In other words, if the dislocations can be prevented from accumulating in the polycrystal, it is expected that the bending characteristics will be improved.

As described above, the rolled copper foil according to the embodiment of the present invention has a crystal structure in which copper cubic crystals are three-dimensionally well aligned, and is a cubic aggregate mainly composed of {200} _Cu planes. Since the structure is a rolled copper foil with few twin structures on the {200} _Cu plane, it is considered that there is a high probability that dislocations will cross-slip during bending. As a result, it is considered that the crystal grain boundary or the like is less likely to become an obstacle to the movement of dislocations, and the bending characteristics are improved (the bending life is increased).

  In other words, in order to cause cross slip effectively, at least both Δβ and Δθ must be excellent (small), that is, excellent in triaxial orientation (for example, Δβ ≦ 10). ° and Δθ ≦ 10 °).

This is because even if a so-called cubic texture has developed (in general, it means that the occupancy of {200} _Cu plane is high with respect to the rolled surface), if Δβ is not small, the slip direction between adjacent grains is This is because it is difficult to cross and slip.

In addition to the triaxial orientation of the cubic texture, it is also an important factor that the rolled copper foil has a small twin structure on the {200} _Cu plane (for example, [a] / [b] ≧ 3). Conceivable. This is because the main {200} _Cu plane and its twin region are not in parallel relation, so the slip direction of each plane is naturally different, and the twin plane can be an obstacle to dislocation movement.

[Third embodiment of the present invention]
(Standardized average strength)
In the rolled copper foil in the present embodiment, the α angle is 35 to 75 in the XRD pole figure measurement of the {111} _Cu plane based on the rolled surface in the state after the final cold rolling step and before recrystallization annealing. The normalized average intensity in the range of ° is not stepped, or there is substantially only one maximum region.

FIG. 7 is obtained by measuring the XRD pole figure of the {111} _Cu plane based on the rolled surface in the rolled copper foil according to the present embodiment, in the state after the final cold rolling step and before the recrystallization annealing. It is an example of a result. As is apparent from FIG. 7, the grain size where the normalized average intensity of the {111} _Cu surface is not stepped in the range of α = 35 to 75 °, or there is substantially only one local maximum region. It shows that the rolled copper foil has an orientation state.

On the other hand, if the normalized average strength of the {111} _Cu surface in the range of α = 35 to 75 ° is a stepped shape or a rolled copper foil in a grain orientation state in which a plurality of maximum regions exist, recrystallization annealing is performed. After that, the ratio of the normalized average strength described above becomes [a] / [b] <3, so that a higher bending characteristic than the conventional one cannot be obtained. Therefore, the rolled copper foil in a grain orientation state in which the normalized average intensity of the {111} _Cu surface in the range of α = 35 to 75 ° is not stepped or has only one maximum region. And

[Fourth embodiment of the present invention]
(Copper alloy composition of rolled copper foil)
The rolled copper foil for FPC in the present embodiment is characterized by being a copper alloy containing 0.001 to 0.009 mass% of Sn and the balance being Cu and inevitable impurities.

  In this Embodiment, the reason for the addition of the alloy component of the copper alloy which comprises the rolled copper foil for FPC, and the reason for limitation of content are demonstrated below.

  In the rolled copper foil, the higher the total degree of processing in the final cold rolling process (for example, 90% or more), the more likely it is to soften at room temperature. When this undesirable phenomenon (normal temperature softening) occurs, the copper foil is easily deformed during the cutting of the copper foil or the lamination with the base material in the FPC manufacturing process, which causes a decrease in yield.

  By containing Sn in Cu, softening at room temperature can be suppressed (softening temperature or recrystallization start temperature can be controlled) even if a strong work is performed in the final cold rolling step. The “normal temperature softening” mentioned here includes a partial recrystallization phenomenon (details will be described later) during the cold rolling process.

  As the Sn content increases, the softening temperature of the rolled copper foil increases. When Sn is less than 0.001% by mass, it is difficult to control to a desired softening temperature. Moreover, when Sn is more than 0.009 mass%, the softening temperature becomes too high, and recrystallization annealing in the above-described CCL process becomes difficult, and there is a problem that electric conductivity is lowered.

  Therefore, the Sn content is set to 0.001 to 0.009 mass%. More preferably, it is 0.002-0.008 mass%, More preferably, it is 0.003-0.007 mass%.

[Fifth embodiment of the present invention]
(Average grain size of recrystallized grains in rolled copper foil)
The rolled copper foil in the present embodiment is characterized in that the average grain size of the recrystallized grains observed on the rolled surface is 40 μm or more in a state where recrystallization annealing is performed after the final cold rolling step. .

As described above, if the dislocation accumulation (or an obstacle that hinders the movement of dislocations) can be suppressed in the polycrystal, it is expected that the bending characteristics are improved. In other words, in addition to a state in which copper cubic crystals are well aligned three-dimensionally and have a crystal structure with few twin structures on the {200} _Cu plane, the grain size of the recrystallized grains is increased (grain boundaries) By reducing itself, the effect of improving the bending characteristics becomes more remarkable.

  However, even if the crystal grain boundaries are reduced, if the triaxial orientation of the recrystallized grains is low, the effect of improving the bending characteristics is small. That is, it is a precondition that the rolled copper foil in the present embodiment also has a crystal grain orientation that causes dislocations to cross and slip during bending motion. Further, in order to make the average grain size of recrystallized grains 40 μm or more, the total degree of work in the final cold rolling process is increased (for example, 94% or more), and at the same time, the recrystallization phenomenon during the cold rolling process This can be achieved by suppressing (details will be described later).

  On the other hand, if the average grain size of the recrystallized grains is smaller than 40 μm, it is not possible to obtain higher bending characteristics than in the past. Therefore, the average grain size of the recrystallized grains is set to 40 μm or more. More desirably, it is 50 μm or more, and further desirably 60 μm or more.

[Method for producing rolled copper foil]
FIG. 8 is a diagram showing an overall flow of a manufacturing process in the rolled copper foil according to the embodiment of the present invention. The rolled copper foil of the present embodiment is provided with tough pitch copper (JIS H3100 C1100), oxygen-free copper (JIS H3100 C1020), or copper alloy ingot (ingot) containing the above components as a raw material (step a). Then, a hot rolling step (step b) for performing hot rolling, a cold rolling step (step c) for performing cold rolling after the hot rolling step, and intermediate annealing for relaxing work hardening by cold rolling. An annealed rolled copper foil called “dough” is manufactured by appropriately repeating the step (step d). Note that the intermediate annealing step immediately before the “dough” may be referred to as a “dough annealing step” (step d ′). In the “fabric annealing step”, it is desirable that processing strain before that is sufficiently relaxed (for example, substantially complete annealing).

  Thereafter, the final cold rolling step (step e, sometimes referred to as “finish rolling step”) is applied to the “dough” to produce a rolled copper foil for FPC having a predetermined thickness. In addition, the rolled copper foil at this time exists in the state of work hardening (state which has not been annealed).

  The rolled copper foil after the final cold rolling process is subjected to surface treatment or the like as necessary (process f) and supplied to the FPC manufacturing process (process g). As described above, the recrystallization annealing (step g ′) is often performed in the step g (for example, the CCL step).

  In the present invention, the “final cold rolling step” means the step e, and the “recrystallization annealing” step g ′ means that performed in the step g.

  The method for producing a rolled copper foil in the present invention is characterized in that the total degree of work in the final cold rolling step before recrystallization annealing is set to 94% or more, and the degree of work per pass is controlled to 15 to 50%. And Further, in the final cold rolling step, control is performed such that “the degree of processing in the first pass” ≧ “the degree of processing in the second pass” ≧ “the degree of processing in the third pass” and 1 after the third pass. The degree of processing per pass is controlled to 15 to 25%.

  The total work degree is defined as “total work degree (%) = {1− (plate thickness after final cold rolling step / sheet thickness of dough)} × 100”. The degree of work per pass refers to the reduction rate of the sheet thickness when passing through a pair of rolling rolls, and “work degree per pass (%) = {1− (after one rolling process). Plate thickness / plate thickness before rolling)} × 100 ”.

In the final cold rolling process before recrystallization annealing, the total workability was set to 94% or more because the {220} _Cu plane orientation (rolling texture) was developed with respect to the rolling surface, and the subsequent recrystallization annealing. This is to achieve {200} _Cu plane orientation (cubic texture) having an occupation ratio of 90% or more on the rolled surface. Moreover, it is for making the average particle diameter of a recrystallized grain 40 micrometers or more by this recrystallization annealing.

Further, in the final cold rolling step before recrystallization annealing, the degree of work per pass is controlled to 15 to 50%, and in particular, “degree of work in the first pass” ≧ “degree of work in the second pass” ≧ In order to control to the “degree of processing in the third pass” and to control the degree of processing in the third pass and beyond to 15 to 25%, it is XRD pole figure measurement of {111} _Cu plane in the rolling texture. This is to achieve a grain orientation state in which the normalized average intensity of the {111} _Cu plane is not stepped in the range of α = 35 to 75 °, or there is substantially only one maximum region. .

  In the final cold rolling process, if the total workability is less than 94% or the workability control per pass is out of the above conditions, it is insufficient to achieve the object. Therefore, the total processing degree is set to 94% or more, and the processing degree per pass is controlled to 15 to 50%. Further, control is performed so that “the degree of machining in the first pass” ≧ “the degree of machining in the second pass” ≧ “the degree of machining in the third pass”, and the degree of machining after the third pass is controlled to 15 to 25%. It is preferable to do.

[Consideration of processing degree control]
The stress applied during the rolling process is considered to be divided into “tensile stress component” and “compressive stress component” with respect to the object. Moreover, in the cold rolling process with respect to copper foil, the copper crystal in copper foil raise | generates a rotation phenomenon with the stress at the time of a rolling process, and forms a rolling texture with progress of a process. At this time, the rotation direction of the crystal depending on the stress direction (orientation oriented on the rolling surface) is generally {220} _Cu surface in the case of compressive stress and {311} _Cu surface or {211} _{Cu in} the case of tensile stress. Surface.

In the conventional rolled copper foil, from the above viewpoint, the total degree of work in the final cold rolling process and the degree of work per pass are set high, and the {220} _Cu plane orientation (rolling set) is increased by increasing the compressive stress. Organization).

  Moreover, in the conventional rolled copper foil, paying attention only to the total workability in the final cold rolling process, no special consideration has been given to the workability per pass. However, when trying to increase the total processing degree, it is considered normal to set the processing degree per pass higher from the viewpoint of reducing the number of processing passes.

However, the metal crystallographic detailed study by the present inventors has set the workability per pass higher, and when the total workability is increased, it is partially in the middle of the final cold rolling process. It was found that a recrystallization phenomenon or the like occurred and hindered the formation of {220} _Cu plane orientation (rolling texture). Needless to say, the inhibition of {220} _Cu plane orientation (rolling texture) formation inhibits the triaxial orientation of the cubic texture due to recrystallization annealing (particularly, the in-plane orientation degree Δβ is degraded).

Therefore, in the present invention, contrary to the prior art, a manufacturing method has been invented in which the degree of processing (accumulated processing strain) is increased while the degree of processing (compression stress) per pass is controlled to be low. Thereby, {220} _Cu plane orientation (rolling texture) can be formed while suppressing recrystallization (relaxation of processing strain) during the final cold rolling process. Note that the formation of {220} _Cu plane orientation (rolling texture) while suppressing recrystallization during the final cold rolling process is realized in the above-described second embodiment of the present invention.

[Other Embodiments]
In step a, the melting / casting method is not limited, and the material dimensions are not limited. There are no particular restrictions on step b, step c, and step d, and ordinary methods and conditions may be used. Moreover, generally the thickness of the rolled copper foil used for FPC is 50 micrometers or less, and if the thickness of the rolled copper foil of this invention is 50 micrometers or less, there will be no restriction | limiting.

[Manufacture of flexible printed wiring boards]
A flexible printed wiring board can be obtained by the manufacturing method currently performed normally using the rolled copper foil of the said embodiment. Further, the recrystallization annealing for the rolled copper foil may be a heat treatment performed in a normal CCL process or may be performed in a separate process.

[Effect of the embodiment]
According to the above embodiment of the present invention, the following effects can be obtained.
(1) A rolled copper foil having bending properties superior to those of the conventional art can be obtained.
(2) A rolled copper foil having bending properties superior to those of conventional ones can be stably produced.
(3) A flexible wiring such as a flexible printed wiring board (FPC) having bending characteristics superior to those of the conventional one can be obtained.
(4) Not only the flexible printed wiring board (FPC) but also other conductive members that require high bending characteristics (flexing life).

  EXAMPLES Hereinafter, although this invention is demonstrated in more detail based on an Example, this invention is not limited to these.

(Production of Example 1 and Comparative Examples 1 to 3)
First, oxygen-free copper (oxygen content 2 ppm) was produced as a raw material, and an ingot having a thickness of 200 mm and a width of 650 mm was produced. Then, after performing hot rolling to a thickness of 10 mm according to the flow shown in FIG. 8, cold rolling and intermediate annealing are repeated as appropriate to produce fabrics having two thicknesses of 0.8 mm and 0.2 mm. did. In addition, as material | dough annealing, the heat processing hold | maintained for about 1 minute at the temperature of 700 degreeC was performed.

  Next, by carrying out the final cold rolling step under the conditions shown in Table 1, a rolled copper foil (Example 1 and Comparative Examples 1 to 3) having a thickness of 16 μm was produced. In addition, five samples were produced in each condition (each rolled copper foil).

  As shown in Table 1, Example 1 is a rolled copper foil according to an embodiment of the present invention. Comparative Example 1 is a rolled copper foil whose workability per pass in the final cold rolling process deviates from the requirements of the present invention. Comparative Example 2 is a rolled copper foil in which the total degree of work in the final cold rolling process deviates from the requirements of the present invention. Comparative Example 3 is a rolled copper foil that deviates from the requirements of the present invention for both the total workability in the final cold rolling process and the workability per pass.

(Grain orientation state of rolled copper foil after final cold rolling process)
{111} _Cu surface XRD on the basis of the rolled surface in the processed state of each rolled copper foil (thickness 16 μm) produced as described above (after the final cold rolling step and before recrystallization annealing) The pole figure measurement results are shown in FIGS.

An X-ray diffractometer (manufactured by Rigaku Corporation, model: RAD-B) was used for various XRD measurements (pole diagram measurement, in-plane orientation measurement, rocking curve measurement, 2θ / θ measurement). The counter cathode (target) was Cu, and the tube voltage and tube current were 40 kV and 30 mA, respectively. The size of the sample used for XRD measurement was about 15 × about 15 mm ² .

The XRD pole figure is measured by using a general Schulz reflection method, and a range of α = 15 to 90 ° (α = 90 ° in the direction perpendicular to the rolling surface) is set to a β angle of 0 to 1 ° step by step. While scanning (rotating) up to 360 °, the diffraction intensity of the {111} _Cu surface was measured (2θ≈43 °, and the 2θ value was the result of preliminary measurement for each sample). The slit conditions at this time were divergent slit = 1 °, scattering slit = 7 mm, light receiving slit = 7 mm, and Schulz slit (slit height 1 mm).

FIG. 9 is an example of the XRD pole figure measurement result of the {111} _Cu plane based on the rolled surface in Example 1. FIG. 9A shows the normalized average intensity of the {111} _Cu plane diffraction peak obtained by β scanning at each α angle, and FIG. 9B shows a positive dot diagram.

FIG. 10 is an example of the XRD pole figure measurement result of the {111} _Cu plane based on the rolled surface in Comparative Example 1. FIG. 10A shows the normalized average intensity of the {111} _Cu plane diffraction peak obtained by β scanning at each α angle, and FIG. 10B shows a positive dot diagram.

FIG. 11 is an example of the XRD pole figure measurement result of the {111} _Cu plane based on the rolled surface in Comparative Example 2. FIG. 11A shows the normalized average intensity of the {111} _Cu plane diffraction peak obtained by β scanning at each α angle, and FIG. 11B shows a positive dot diagram.

FIG. 12 is an example of the XRD pole figure measurement result of the {111} _Cu plane based on the rolled surface in Comparative Example 3. FIG. 12A shows the normalized average intensity of the {111} _Cu plane diffraction peak obtained by β scanning at each α angle, and FIG. 12B shows a positive dot diagram.

  In FIG. 9A, FIG. 10A, FIG. 11A, and FIG. 12A, the arrows in the figure indicate portions where the normalized average intensity is stepped or maximal. . As is apparent from the figure, in the range of α = 35 to 75 °, there is substantially only one local maximum region in Example 1, whereas there are at least two locations in Comparative Examples 1 to 3. .

  Here, corresponding to the maximum region in the range of α = 40 to 45 ° in FIGS. 10 (a) and 12 (a), as indicated by the arrows in FIGS. 10 (b) and 12 (b). In addition, a diffraction peak having a 4-fold symmetry is confirmed. This four-fold symmetry diffraction peak is considered to be caused by a recrystallization phenomenon during the cold rolling process. Comparative Examples 1 and 3 are rolled copper foils whose degree of work per pass in the final cold rolling process is larger than the requirements of the present invention (see Table 1), and the degree of work per pass is cold rolled. This suggests that it strongly affects the recrystallization phenomenon during processing.

  On the other hand, in FIG. 11B, a four-fold symmetry diffraction peak corresponding to the stepped region in the range of α = 40 to 45 ° in FIG. However, since Comparative Example 2 is a rolled copper foil whose total workability in the final cold rolling process is smaller than the requirements of the present invention (see Table 1), the rotation phenomenon of copper crystals in the cold rolling work is insufficient. Therefore, it is considered that a stepped region in the range of α = 40 to 45 ° in FIG.

The relationship between the processing conditions of the final cold rolling process and the crystal grain orientation state of the finished rolled copper foil will be summarized. In the final cold rolling step before recrystallization annealing, the total workability is set to 94% or more, and the workability per pass is controlled to 15 to 50%. In particular, “workability in the first pass” ≧ “2 Recrystallization during the final cold rolling process is performed by controlling the degree of processing at the pass “≧“ degree of processing at the third pass ”and controlling the degree of processing after the third pass to 15 to 25%. It can be seen that {220} _Cu plane orientation (rolling texture) can be formed which suppresses the phenomenon and promotes the rotation phenomenon of the copper crystal.

On the contrary, if the “total workability” or “workability per pass” deviates from the requirement of the present invention, a recrystallization phenomenon during rolling and insufficient crystal rotation occur, and {220} in the rolled copper foil. Inhibits effective formation of _Cu plane orientation (rolling texture). In addition, recrystallization phenomenon during rolling and insufficient crystal rotation are caused by XRD pole figure measurement of {111} _Cu plane based on the rolling surface (particularly the {111} _Cu obtained by β scanning at each α angle). It can be determined by the normalized average intensity of the surface diffraction peak.

(Grain orientation state of rolled copper foil after recrystallization annealing)
Each rolled copper foil produced as described above (thickness 16 μm, final cold rolling process increased) is subjected to recrystallization annealing that is held at a temperature of 180 ° C. for 60 minutes, and then each is performed using an X-ray diffractometer. The crystal grain orientation state of the rolled copper foil was evaluated.

When the {200} _Cu plane occupancy of the cube texture was evaluated by XRD · 2θ / θ measurement (average of 5 samples each), Example 1 was about 94%, Comparative Example 1 was about 91%, and Comparative Example 2 was About 89% and Comparative Example 3 were about 88%.

Moreover, the XRD rocking curve measurement was performed as follows. Diffraction peak obtained when the detector is fixed to the 2θ value of the {200} _Cu plane diffraction peak obtained by XRD · 2θ / θ measurement of each rolled copper foil and the sample is scanned from θ = 15 to 35 °. The half-value width Δθ of was calculated. The slit conditions in 2θ / θ measurement and rocking curve measurement were 1 ° for the diverging slit, 0.15 mm for the light receiving slit, and 1 ° for the scattering slit. The measurement results of Δθ (average of 5 samples each) are about 7.8 ° in Example 1, about 8.6 ° in Comparative Example 1, about 7.3 ° in Comparative Example 2, and about 10. in Comparative Example 3. It was 4 °.

Moreover, the XRD in-plane orientation measurement was performed as follows. First, the 2θ value of the {111} _Cu surface is obtained in advance for each rolled copper foil (each sample) (for example, in-plane orientation measurement of the {111} _Cu surface using the {111} _Cu surface 2θ value from JCPDS, etc.) And the 2θ / θ measurement is performed with the sample surface set to α = 35 ° using the β value having the highest diffraction intensity, and the 2θ value of the {111} _Cu surface of the sample can be obtained. ). Thereafter, the average half value of the four-fold symmetry diffraction peak obtained when the detector is fixed to the 2θ value of the {111} _Cu surface of the sample and the sample is β-axis scanned (β = 0 to 360 °). The width Δβ was calculated. The measurement results of Δβ (average of 5 samples each) were about 8.3 ° in Example 1, about 8.8 ° in Comparative Example 1, about 9.8 ° in Comparative Example 2, and about 11. in Comparative Example 3. It was 8 °.

In addition, the evaluation of the normalized average intensity ratio of the {111} _Cu surface is carried out in the same way as described above in the XRD pole figure measurement by the Schulz reflection method (the β angle is set to 0 for each 1 ° step in the range of α = 15 to 90 °). The diffraction intensity of the {111} _Cu surface is measured while scanning up to 360 °), the normalized average intensity [a] of the {111} _Cu surface at α = 35 °, and the normalized average intensity [b] at α = 74 ° ] Ratio was determined. FIG. 13 is an example of a graph of normalized average intensity in Example 1. FIG. 14 is an example of a graph of normalized average intensity in Comparative Example 3. The results of normalized average strength ratio (average of 5 samples each) were about 4.5 for Example 1, about 2.9 for Comparative Example 1, about 2.0 for Comparative Example 2, and about Comparative Example 3. 1.7.

  Table 2 shows various XRD measurement results for the rolled copper foil after the recrystallization annealing.

The relationship of the crystal grain orientation state of the rolled copper foil before and after recrystallization annealing will be summarized. As is clear from the results in Table 2, a rolled copper foil obtained by subjecting a rolled copper foil having a crystal grain orientation state as shown in FIG. 9 to recrystallization annealing has three parts: {200} _Cu plane occupancy, Δθ, and Δβ. The index indicates that the cubic texture has a very high triaxial orientation. Furthermore, the index of the normalized average strength ratio ([a] / [b]) indicates that the rolled copper foil has few twin structures on the {200} _Cu plane in addition to the triaxial orientation of the cubic texture. ing.

In contrast, a rolled copper foil obtained by subjecting a rolled copper foil having a grain orientation state as shown in FIGS. 10 to 12 to recrystallization annealing has four indices ({200} _Cu plane occupancy, Δθ, Δβ, normalized) Any one or more of (average intensity ratio) is inferior, the triaxial orientation of the cube texture is inferior (inhibited), and / or the twin structure of {200} _Cu plane in the cube texture It shows that it is a rolled copper foil.

(Average crystal grain size of rolled copper foil after recrystallization annealing)
Evaluation of the average crystal grain size for each rolled copper foil (thickness 16 μm, after recrystallization annealing) produced as described above was performed as follows. The surface of the rolled copper foil is a mixed solution of hydrogen peroxide water (for example, Wako Pure Chemical Industries, Ltd., product number: 080-01186) and ammonia water (for example, Wako Pure Chemical Industries, Ltd., product number: 017-03176). After etching with absorbent cotton moistened with 10 ml of ammonia water + 2 to 3 drops of hydrogen peroxide solution (to wipe the surface to be etched once or twice with absorbent cotton), an optical microscope (Olympus Corporation) Photo was taken using a model manufactured by PMG3). For this photograph, the average crystal grain size was determined in accordance with the cutting method of JIS H 0501. The results are shown in Table 3.

As is apparent from the results in Table 3, it can be seen that the rolled copper foil of Example 1 has a very large average crystal grain size as compared with Comparative Examples 1 to 3. This result is considered to be due to the extremely high triaxial orientation of the cubic texture in Example 1 and the rolled copper foil (see Table 2) with little twin structure on the {200} _Cu plane.

(Bending characteristics of rolled copper foil after recrystallization annealing)
Evaluation of the bending characteristic with respect to each rolled copper foil (thickness 16 micrometers, after recrystallization annealing) produced as mentioned above was performed as follows. FIG. 15 is a schematic diagram showing an outline of bending characteristic evaluation (sliding bending test). The sliding bending test apparatus is manufactured by Shin-Etsu Engineering Co., Ltd., model: SEK-31B2S, R = 2.5 mm, amplitude stroke = 10 mm, frequency = 25 Hz (amplitude speed = 1500 times / min), sample width = 12.5 mm The sample length was 220 mm, and the measurement was performed under the condition that the longitudinal direction of the sample piece was the rolling direction. The results are shown in Table 4.

As is apparent from the results in Table 4, it can be seen that the rolled copper foil of Example 1 has a flex life (high bending characteristics) twice or more that of Comparative Examples 1 to 3. This result shows that the cubic texture in Example 1 has a very high triaxial orientation, a rolled copper foil (see Table 2) with little twin structure on the {200} _Cu plane, and a large average crystal grain size (see Table 3). It is thought to be caused by

(Production of Examples 2-3 and Comparative Example 4)
A copper alloy (Example 2) in which 0.004 mass% of Sn is added to the oxygen-free copper (oxygen content 2 ppm) as a raw material, and a copper alloy (0.002 mass%) in which Sn is added to the oxygen-free copper 3) and a copper alloy (Comparative Example 4) obtained by adding 0.01% by mass of Sn to the oxygen-free copper were manufactured to produce an ingot having a thickness of 200 mm and a width of 650 mm. Then, after performing hot rolling to a thickness of 10 mm according to the flow shown in FIG. 8, cold rolling and intermediate annealing were appropriately repeated to produce a fabric having a thickness of 0.8 mm. In addition, as material | dough annealing, the heat processing hold | maintained for about 1 minute at the temperature of 700 degreeC was performed.

  Next, by carrying out the final cold rolling process under the same conditions as in Example 1 (see Table 1), a rolled copper foil (Examples 2 to 3 and Comparative Example 4) having a thickness of 16 μm was produced. Note that five samples were prepared under the same conditions (each rolled copper foil) as before.

The softening temperature of the produced rolled copper foil (Examples 2-3 and Comparative Example 4) was investigated. The investigation method was almost based on the tensile test method of JIS Z 2241, and was determined by the tensile strength using a universal testing machine (manufactured by Shimadzu Corporation, model: AG-I). First, a sample piece was cut into a strip shape having a width of 15 mm and a length of 200 mm (the length direction is the rolling direction). For each sample piece cut out, 50 ° C, 100 ° C, 130 ° C, 160 ° C, 180 ° C, 200 ° C, 220 ° C, 240 ° C, 260 ° C, 280 ° C, 300 ° C, 320 ° C, 340 ° C, 360 ° C Heat treatment was performed at each temperature for 30 minutes. The tensile strength of each sample piece after heat treatment was measured, and the temperature at which the decrease in strength was almost saturated (about 110 to 150 N / mm ² ) was defined as the softening temperature (note that the tensile strength of the rolled copper foil before heat treatment was 380 to 380). About 480 N / mm ² ).

  As a result of the investigation (average of 5 samples each), the softening temperature of Example 2 was about 180 ° C., the softening temperature of Example 3 was about 260 ° C., and the softening temperature of Comparative Example 4 was about 320 ° C. . In addition, the softening temperature of oxygen-free copper (Example 1) which does not contain Sn component was about 100 degreeC.

  These rolled copper foils were subjected to heat treatment under conditions assuming recrystallization annealing in the CCL process (held at a temperature of 300 ° C. for 10 minutes), and then evaluated for the average crystal grain size and bending characteristics (sliding) as described above. Dynamic bending test). Table 5 shows the evaluation results of the average crystal grain size, and Table 6 shows the evaluation results of the bending characteristics.

  When considering the results of Tables 3 to 6 comprehensively, the rolled copper foils of Examples 2 and 3 were subjected to necessary and sufficient recrystallization annealing, so that conventional rolled copper foils (Comparative Examples 1 to 3) were used. It is considered that the number of flexing lifespans (high flexing characteristics) was twice or more as compared with. For the same reason, it is considered that the average crystal grain size after the heat treatment had a sufficient size (40 μm or more).

Moreover, when the XRD pole figure measurement of the {111} _Cu surface on the basis of the rolling surface was performed on the rolled copper foils of Examples 2 and 3 subjected to the heat treatment, the same results as in FIGS. 3 and 13 were obtained. It was confirmed that it had a crystal grain orientation state where Δβ ≦ 10 ° and [a] / [b] ≧ 3.

On the other hand, Comparative Example 4 in which the content of the Sn component is larger than the requirements of the present invention was inferior to the conventional rolled copper foil (Comparative Examples 1 to 3) in bending properties. Therefore, XRD pole figure measurement was performed on the rolled copper foil of Comparative Example 4 subjected to the heat treatment. FIG. 16 is a graph of the normalized average intensity of the {111} _Cu plane diffraction peak obtained by β scanning for each α angle by XRD pole figure measurement of the {111} _Cu plane relative to the rolled surface in Comparative Example 4. This is an example.

  As is apparent from the results in the figure, [a] / [b] <3, and it can be seen that diffraction due to recrystallization and diffraction due to rolling texture are mixed. This is presumably because sufficient recrystallization annealing was not performed because the content of the Sn component was too large.

It is a schematic diagram which shows the main crystal planes of a copper crystal. It is the schematic which shows the relationship of the incident X-ray in X-ray diffraction, a detector, a sample, and a scanning axis. In the rolled copper foil according to the present embodiment, the position of 55 ° (α = 35 ° on the measurement condition) with respect to the {200} _Cu surface of the rolled surface in a state where recrystallization annealing is performed after the final cold rolling step. It is an example of the result of having performed the XRD in-plane orientation measurement of the {111} _Cu surface which is related. In the rolled copper foil which concerns on this Embodiment, it is an example of the result obtained by the XRD pole figure measurement of the {111} _Cu surface on the basis of a rolling surface in the state which gave recrystallization annealing after the last cold rolling process. is there. In the rolled copper foil which concerns on this Embodiment, it is an example of the result of having performed X-ray diffraction 2 (theta) / (theta) measurement with respect to the rolling surface in the state which gave recrystallization annealing after the last cold rolling process. In the rolled copper foil which concerns on this Embodiment, it is an example of the result of having performed the XRD rocking curve measurement of the {200} _Cu surface with respect to a rolling surface in the state which gave recrystallization annealing after the last cold rolling process. . In the rolled copper foil which concerns on this Embodiment, it is an example of the result obtained by the XRD pole figure measurement of the {111} _Cu surface on the basis of a rolling surface in the state after a final cold rolling process and before recrystallization annealing. is there. It is a figure which shows the whole flow of the manufacturing process in the rolled copper foil of embodiment of this invention. It is an example of the XRD pole figure measurement result of the {111} _Cu surface on the basis of the rolling surface in Example 1. FIG. 9A shows the normalized average intensity of the {111} _Cu plane diffraction peak obtained by β scanning at each α angle, and FIG. 9B shows a positive dot diagram. It is an example of the XRD pole figure measurement result of the {111} _Cu surface on the basis of the rolling surface in the comparative example 1. FIG. 10A shows the normalized average intensity of the {111} _Cu plane diffraction peak obtained by β scanning at each α angle, and FIG. 10B shows a positive dot diagram. It is an example of the XRD pole figure measurement result of the {111} _Cu surface on the basis of the rolling surface in the comparative example 2. FIG. 11A shows the normalized average intensity of the {111} _Cu plane diffraction peak obtained by β scanning at each α angle, and FIG. 11B shows a positive dot diagram. It is an example of the XRD pole figure measurement result of the {111} _Cu surface on the basis of the rolling surface in the comparative example 3. FIG. 12A shows the normalized average intensity of the {111} _Cu plane diffraction peak obtained by β scanning at each α angle, and FIG. 12B shows a positive dot diagram. 2 is an example of a graph of normalized average intensity in Example 1. FIG. It is an example of the graph of the normalization average intensity | strength in the comparative example 3. It is a schematic diagram showing the outline of bending characteristic evaluation (sliding bending test). It is an example of the graph of the normalized average intensity | strength of this {111} _Cu surface diffraction peak obtained by (beta) scanning with respect to each (alpha) angle by the XRD pole figure measurement of the {111} _Cu surface on the basis of the rolling surface in the comparative example 4. .

Explanation of symbols

1: Copper foil 2: Sample fixing plate 2a: Screw 3: Vibration transmitting unit 4: Oscillation driver R: Curvature

Claims (7)

In the rolled copper foil subjected to recrystallization annealing after the final cold rolling step, the result obtained by X-ray diffraction pole figure measurement based on the rolled surface shows that {111} _Cu relative to the {200} _Cu surface of the rolled surface The in-plane orientation degree Δβ of the surface is 10 ° or less,
And wherein by β scanning in the alpha = 35 ° in X-ray diffraction pole figure measurement {111} normalized average intensity of the _Cu surface diffraction peak [a] and alpha = the by β scanning at 74 ° {111} _Cu plane diffraction peak A rolled copper foil characterized by having a grain orientation state in which the ratio of normalized average strength [b] of [a] / [b] ≧ 3. The rolled copper foil according to claim 1, wherein 90% or more of the diffraction peak of the copper crystal is the {200} _Cu plane as a result obtained by X-ray diffraction 2θ / θ measurement on the rolled surface.
And the rolled copper foil characterized by the half-value width (DELTA) (theta) of this diffraction peak being 10 degrees or less by the result obtained by the X-ray-diffraction rocking curve measurement of said {200} _Cu surface. Results obtained by X-ray diffraction pole figure measurement based on the rolled surface in the rolled copper foil after the final cold rolling process and before recrystallization annealing, and obtained by β scanning at each α angle {111} _Cu surface When the normalized average intensity of the diffraction peak is plotted, the normalized average intensity in the range of the α angle of 35 to 75 ° is not stepped, or there is substantially only one maximum region. A rolled copper foil having a crystal grain orientation state.   The rolling according to any one of claims 1 to 3, wherein a copper alloy containing 0.001 to 0.009 mass% of Sn as a rolled copper foil and the balance being Cu and inevitable impurities is used. Copper foil.   3. The rolled copper foil subjected to recrystallization annealing after the final cold rolling step has an average grain size of the recrystallized grains observed on the rolled surface of 40 μm or more. And the rolled copper foil of any one of Claim 4. {111} _Cu surface diffraction obtained by β-scanning at each α angle with the results obtained by X-ray diffraction pole figure measurement based on the rolling surface in the rolled copper foil after the final cold rolling process and before recrystallization annealing When the normalized average intensity of the peak is plotted, the normalized average intensity in the range of the α angle of 35 to 75 ° is not stepped, or there is substantially only one maximum region. A method for producing copper foil,
A method for producing a rolled copper foil, characterized in that a total workability in a final cold rolling step before recrystallization annealing is set to 94% or more, and a workability per pass is controlled to 15 to 50%.   It is a manufacturing method of Claim 6, Comprising: In the last cold-rolling process before recrystallization annealing, "working degree of the 1st pass" ≥ "working degree of the 2nd pass" ≥ "working degree of the 3rd pass" ”And the degree of work after the third pass is controlled to 15 to 25%.

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