JP4215093B2 - Rolled copper foil and method for producing the same - Google Patents

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.

  Generally, a rolled copper foil is subjected to hot rolling on an ingot of tough pitch copper (JIS H3100 C1100) or oxygen-free copper (JIS H3100 C1020) as a raw material, 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, bent, 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 additive 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 examined the crystal grain orientation state before recrystallization annealing, the crystal grain orientation state after recrystallization annealing, and the bending characteristics through detailed metallographic studies on the formation of a cubic texture by recrystallization annealing in rolled copper foil. 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 is a result obtained by X-ray diffraction 2θ / θ measurement on a rolled surface in a rolled copper foil after a final cold rolling process and before recrystallization annealing. 80% or more is {220} _Cu plane, and the results obtained by the rolled surface X-ray diffraction pole figure measurement relative to the respective α angle obtained by β scanning in the {111} of the _Cu surface diffraction peaks When the normalized average intensity is plotted, the normalized average intensity is not stepped in the range of the α angle of 35 to 75 °, or there is substantially only one local maximum region. There is provided a rolled copper foil characterized by having a state.

Further, the present invention is a result obtained by X-ray diffraction 2θ / θ measurement on the rolled surface when the recrystallization annealing is performed on the rolled copper foil according to the present invention to achieve the above object. , 90% or more {200} _Cu plane of the diffraction peak of the copper crystals, and the {200} with the results obtained by X-ray diffraction rocking curve measurement of the _Cu surface, diffraction peaks of the integral width (IW _{200} ) And half width (FWHM _{200} ) is 0.85 ≦ IW _{200} / FWHM _{200} ≦ 1.15, and obtained by X-ray diffraction pole figure measurement based on the rolling surface. results for the {200} of the 4-fold symmetry diffraction peaks of {111} _Cu plane to the _Cu surface, one of the diffraction peaks of the integral width (IW _{111}) and the half-width (FWHM _{111}) ratio having a grain orientation state is _{0.85 ≦ IW {111} / FWHM} {111} ≦ 1.15 in Providing a rolled copper foil, characterized in that.

  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.

  Moreover, this invention uses the copper alloy which contains 0.001-0.009 mass% of Sn as a rolled copper foil which concerns on said this invention, and remainder consists of Cu and an unavoidable impurity in order to achieve the said objective. The featured rolled copper foil is provided.

In order to achieve the above object, the present invention is a result obtained by X-ray diffraction 2θ / θ measurement on the rolled surface in the rolled copper foil after the final cold rolling step and before recrystallization annealing. 80% or more of the diffraction peak is a {220} _Cu plane, and {111} _Cu plane diffraction obtained by β scanning at each α angle as a result obtained by X-ray diffraction pole figure measurement based on the rolled surface. 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 a copper foil, 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%. A method for producing a rolled copper foil 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) in the direction perpendicular to the sample surface (rolled surface in the present invention) of the rolled copper foil which 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. The degree of orientation in the direction perpendicular to the rolling surface of the {hkl} _Cu surface can be evaluated by the half width (FWHM _{hkl} ) or the integral width (IW _{hkl} ) of the {hkl} _Cu surface peak obtained by this measurement. At this time, it can be said that the smaller the value of the half width (FWHM _{hkl} ) or the integral width (IW _{hkl} ), the better the crystal orientation in the direction perpendicular to the rolling surface. In other words, since the crystal structure of copper is cubic, the half-value width (FWHM _{hkl} ) or integral width (IW _{hkl} ) is inclined by how much the cube varies with respect to the vertical direction of the rolling surface. It can be thought that it represents. The half width (FWHM _{hkl} ) is the peak width at half the intensity of the diffraction peak, and the integral width (IW _{hkl} ) is the integral intensity of the diffraction peak divided by the maximum intensity of the diffraction peak. Define.

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 °). The {h'k'l '} _Cu surface peak half-value width (FWHM _{h'k'l'} ) or integral width (IW _{{h'k'l '}} ) or { hkl } _Cu surface The degree of orientation in the biaxial direction in the rolling plane can be evaluated. At this time, it can be said that the smaller the value of the half width (FWHM _{{h'k'l '}} ) or the integral width (IW _{h'k'l'} ), the better the crystal orientation in the in-rolling direction. . In other words, the full width at half maximum (FWHM _{{h'k'l '}} ) or integral width (IW _{h'k'l'} ) indicates how much the cube is rotating in the rolling plane (" It can be considered that it is deviated from the “eye”. As described above, the half width (FWHM _{{h'k'l '}} ) is the peak width at half the intensity of the diffraction peak, and the integral width (IW _{h'k'l'} ) is the diffraction peak. Is defined as the integral intensity divided by the maximum intensity of the diffraction peak.

[First embodiment of the present invention]
(2θ / θ measurement)
In the rolled copper foil in the present embodiment, the rolling surface is strongly oriented to the {220} _Cu surface of the copper crystal after the final cold rolling step and before the recrystallization annealing, and the occupation ratio is 80%. It is the above.

FIG. 3 shows an example of the result of X-ray diffraction 2θ / θ measurement performed on the rolled surface in the state after the final cold rolling step and before recrystallization annealing in the rolled copper foil according to the present embodiment. It is. As apparent from FIG. 3, the rolled surface is strongly oriented to the {220} _Cu plane, the {220} _Cu surface occupation ratio is 80% or more. This has shown that it is the rolled copper foil in which the favorable rolling texture was formed.

On the other hand, if the {220} _Cu plane occupancy is less than 80%, higher bending characteristics than in the prior art cannot be obtained in the rolled copper foil subjected to recrystallization annealing. Therefore, the {220} _Cu plane occupancy is 80% or more. More desirably, it is 85% or more, and more desirably 90% or more.

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

(Standardized average strength)
Further, the rolled copper foil in the present embodiment has an α angle of 35 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 the recrystallization annealing. The normalized average intensity in a range of ˜75 ° is not stepped, or there is substantially only one maximum region.

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).

FIG. 4 is obtained by measuring the XRD pole figure of the {111} _Cu surface based on the rolled surface in the rolled copper foil according to the present embodiment, after the final cold rolling step and before the recrystallization annealing. It is an example of a result. As is apparent from FIG. 4, the crystal grains in which the normalized average intensity of the {111} _Cu plane is not stepped in the range of α = 35 to 75 °, or only one local maximum region exists. It shows that the rolled copper foil has an orientation state. This indicates that the recrystallization phenomenon during the cold rolling process is suppressed and a good rolling texture is formed (details will be described later).

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 thereafter. In the rolled copper foil which was given, a bending characteristic higher than before 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

[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 grain in a state where the above-described rolled copper foil is subjected to recrystallization annealing, and the occupation ratio thereof Is 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 {200} _Cu surface occupancy is 90% or more. This has shown that it is the rolled copper foil in which the cube texture was formed.

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

The {200} _Cu plane occupancy was defined as follows.
{200} _Cu plane occupancy (%) = [I _{{200} Cu} / (I _{{111} Cu} + I _{{200} Cu} + I _{{220} Cu} + I _{{311} Cu} )] × 100

(Rocking curve measurement)
Further, the rolled copper foil in the present embodiment is a result obtained by measuring the rocking curve of the {200} _Cu surface that is strongly oriented on the rolled surface in a state where recrystallization annealing is performed after the final cold rolling step. The ratio of the half width (FWHM _{200} ) and the integral width (IW _{200} ) of the diffraction peak is 0.85 ≦ IW _{200} / FWHM _{200} ≦ 1.15 .

In the present invention, focusing on the diffraction lines of the recrystallized grains of {200} _Cu plane, which accounts for more than 90% of the rolling surface as described above, {200} FWHM as grain orientation of _Cu plane (FWHM _{200}) And the integral width (IW _{200} ). The ratio of the half width (FWHM _{200} ) to the integral width (IW _{200} ) is 0.85 or more and 1.15 or less, that is, FWHM _{200} and IW _{200} are substantially the same value. Means that the ratio of crystal grains having an orientation in which the diffraction peak has a small tail and the fluctuation width of the crystal orientation is small (with a very small tilt deviation) is high. For example, as the diffraction peak shape approaches a trapezoid or a rectangle, the ratio of FWHM _{200} to IW _{200} (IW _{200} / FWHM _{200} ) approaches 1.

On the other hand, when the ratio (IW _{200} / FWHM _{200} ) of FWHM _{200} and IW _{{200} on} the {200} _Cu surface is smaller than 0.85 or exceeds 1.15, it is higher than the conventional case. Bending characteristics cannot be obtained. Therefore, it is set to 0.85 or more and 1.15 or less. More desirably, it is 0.9 or more and 1.1 or less. Needless to say, the smaller absolute values of FWHM _{200} and IW _{200} are preferred from the viewpoint of crystal grain orientation. For example, in FWHM _{200}, it is preferably 10 ° or less, more preferably 9.5 ° or less, and further preferably 9 ° or less.

(In-plane orientation measurement)
In addition, the rolled copper foil in the present embodiment has a 55 ° positional relationship with respect to the {200} _Cu plane that is strongly oriented on the rolled surface in a state where recrystallization annealing is performed after the final cold rolling step. In the 4-fold symmetrical diffraction peak obtained by measuring the XRD in-plane orientation of the {111} _Cu surface, the ratio of the half width (FWHM _{111} ) to the integral width (IW _{111} ) of any one diffraction peak is 0.85 ≦ IW _{111} / FWHM _{111} ≦ 1.15.

In the present invention, in a state where recrystallization annealing is performed after the final cold rolling step, the positional relationship of {111} is 55 ° (α = 35 ° on measurement conditions) with respect to the {200} _Cu surface of the rolled surface. focusing on the diffraction lines of the _Cu surface, to evaluate the ratio of the half width as plane orientation degree of {111} _Cu plane (FWHM _{111}) and integral width (IW _{111}). 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).

Since the rolled surface is oriented to the {200} _Cu surface, when measuring {111} _Cu surface diffraction, four peaks, that is, four-fold symmetry diffraction peaks appear (the rolling direction is β = 0 °). The center of each peak is, for example, β≈45 °, 135 °, 225 °, 315 °). If the {200} _Cu plane of the recrystallized grains occupies about 90% or more of the rolled surface, the other than the four peaks are hardly detected by β scanning.

As described above, the ratio of the half width (FWHM _{111} ) to the integral width (IW _{111} ) is 0.85 or more and 1.15 or less, that is, FWHM _{111} and IW _{111} are The substantially equal value means that the diffraction peak has a shape with little tailing and the ratio of crystal grains having an orientation in which the fluctuation width of the crystal orientation is small (with a very small inclination deviation) is high. For example, the closer the diffraction peak shape is to a trapezoid or rectangle, the closer the ratio of FWHM _{111} to IW _{111} (IW _{111} / FWHM _{111} ) approaches 1.

On the other hand, when the ratio of FWHM _{111} to IW _{111} (IW _{111} / FWHM _{111} ) on the {111} _Cu surface is smaller than 0.85 or exceeds 1.15, it is higher than the conventional case. Bending characteristics cannot be obtained. Therefore, it is set to 0.85 or more and 1.15 or less. More desirably, it is 0.9 or more and 1.1 or less. Needless to say, the smaller absolute values of FWHM _{111} and IW _{111} are preferable from the viewpoint of crystal grain orientation. For example, in FWHM _{111}, it is preferably 10 ° or less, more preferably 9.5 ° or less, and further preferably 9 ° or less.

The crystal grain orientation states so far are summarized. In the rolled copper foil according to the embodiment of the present invention, first, in a state after the final cold rolling step and before the recrystallization annealing, a good rolling texture (80% or more {220} _Cu plane occupation rate, and Suppression of the recrystallization phenomenon during the cold rolling process) is formed. Further, in a state where the recrystallized annealing is performed on the rolled copper foil, the {200} _Cu plane occupation ratio is 90% or more, the fluctuation width of the {200} _Cu plane is small, and the fluctuation width of the {111} _Cu plane A small cubic texture is formed. This can be regarded as being in a state (crystal grain orientation state) in which copper cubic crystals are well aligned three-dimensionally.

(Mechanism for high bending properties)
Next, a mechanism for achieving high bending characteristics in the rolled copper foil according to the embodiment of the present invention will be briefly described.

  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 (the state in which recrystallization annealing is performed after the final cold rolling process) has a crystal structure in which copper cubic crystals are well aligned three-dimensionally. Therefore, it is considered that there is a high probability that dislocations cross-slip during bending motion. 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 the {200} _Cu plane occupancy is high, the fluctuation width of the {200} _Cu plane is small, and the fluctuation width of the {111} _Cu plane is small. That is, it is necessary to have excellent triaxial orientation (for example, {200} _Cu plane occupancy ≧ 90%, 0.85 ≦ IW _{200} / FWHM _{200} ≦ 1.15 and 0.85 ≦ IW _{111} / FWHM _{111} ≦ 1.15).

This is because even if a so-called cubic texture develops (in general, it means that the occupancy of the {200} _Cu surface is high with respect to the rolling surface), the fluctuation of the {200} _Cu surface or {111} _Cu surface is small. Otherwise, the slip direction is easily shifted between adjacent crystal grains, and cross slip is less likely to occur.

[Third 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 the crystal grain orientation state in which copper cubic crystals are well aligned three-dimensionally, by increasing the grain size of the recrystallized grains (decreasing the grain boundaries themselves), the effect of improving the bending properties is further improved. Become prominent.

  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.

[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. Note that 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%.

[Method for producing rolled copper foil]
FIG. 6 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 a 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 {220} _Cu plane orientation (rolling texture) having an occupation ratio of 80% or more to the rolling surface. This is to achieve {200} _Cu plane orientation (cubic texture) having an occupation ratio of 90% or more on the rolled surface by subsequent recrystallization annealing. 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 not sufficient 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 “degree of machining in the first pass” ≧ “degree of machining in the second pass” ≧ “degree of machining in the third pass” and the degree of machining per pass after the third pass is 15 to It is preferable to control to 25%.

[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.

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) having an occupation ratio of 80% or more can be formed while suppressing recrystallization (relaxation of processing strain) during the final cold rolling process.

[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. 6, 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, the final cold rolling process was performed under the conditions shown in Table 1 to produce a rolled copper foil (Example 1 and Comparative Examples 1 to 3) having a thickness of 16 μm. In each condition (each rolled copper foil), five samples were prepared.

  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 and the workability per pass in the final cold rolling process.

(Grain orientation state of rolled copper foil after final cold rolling process)
For various XRD measurements (2θ / θ measurement, rocking curve measurement, pole figure measurement, in-plane orientation measurement), an X-ray diffractometer (manufactured by Rigaku Corporation, model: RAD-B) was used. 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 2θ / θ measurement was performed using a general wide-angle goniometer in the range of 2θ = 30 to 100 °. The slit conditions in the 2θ / θ measurement were 1 ° for the diverging slit, 0.15 mm for the light receiving slit, and 1 ° for the scattering slit.

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).

X-ray diffraction 2θ / θ measurement and rolling of the rolled surface with respect to the processed state of each rolled copper foil (thickness 16 μm) prepared under the conditions of Table 1 (after the final cold rolling step and before recrystallization annealing) The pole figure of the {111} _Cu plane with respect to the plane was measured. FIG. 7 is an example of X-ray diffraction 2θ / θ measurement results for the rolled surface after the final cold rolling step and before recrystallization annealing. 7A shows Example 1, FIG. 7B shows Comparative Example 1, FIG. 7C shows Comparative Example 2, and FIG. 7D shows Comparative Example 3. FIG.

In addition, in each measurement result shown in FIG. 7, Table 2 shows the relative intensity and {220} _Cu plane occupancy when the diffraction intensity of the strongest line is 100.

As apparent from FIG. 7 and Table 2, Example 1, it can be seen that forms a rolling texture that is strongly oriented in the {220} _Cu plane ({220} _Cu surface occupation ratio ≒ 92%). On the other hand, in Comparative Examples 1 to 3, it can be seen that the {200} _Cu plane is strongly detected and the {220} _Cu plane occupancy is less than 80%.

FIG. 8 is an example of the XRD pole figure measurement result of the {111} _Cu plane based on the rolled surface in Example 1. FIG. 8A shows the normalized average intensity of the {111} _Cu surface diffraction peak obtained by β scanning at each α angle, and FIG. 8B shows a positive dot diagram.

FIG. 9 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. 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 surface based on the rolled surface in Comparative Example 2. 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 3. 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.

  In FIG. 8A, FIG. 9A, FIG. 10A, and FIG. 11A, the arrows in the figure indicate portions where the normalized average strength 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. 9A and 11A, as indicated by the arrows in FIGS. 9B and 11B. 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. Further, 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. 10B, a four-fold symmetry diffraction peak corresponding to the stepped region in the range of α = 40 to 45 ° in FIG. 10A is not confirmed. 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.

Tables 1 and 2 and FIGS. If the degree of processing per pass becomes larger than the requirement of the present invention, a recrystallization phenomenon is induced during cold rolling, and {200} _Cu surface diffraction becomes strong in 2θ / θ measurement, and 4 in pole figure measurement. It is considered that a diffraction peak having a symmetric symmetry is observed. Further, if the total workability becomes smaller than the requirement of the present invention, the rotation phenomenon of the copper crystal by the cold rolling process becomes insufficient, and {200} _Cu plane diffraction is considered to be strongly observed in the 2θ / θ measurement. . Therefore, in Comparative Example 3, the diffraction intensity of the {200} _Cu plane and the {220} _Cu plane in 2θ / θ measurement is “I _{{200} Cu} > I _{{220} Cu} ” due to the combined phenomenon of these factors. It is thought that.

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 (good 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).

(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%. The results are summarized in Table 3.

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 width (FWHM _{200} ) and the integral width (IW _{200} ) were evaluated, and the ratio (IW _{200} / FWHM _{200} ) was calculated. The slit conditions in the rocking curve measurement were the same as in the 2θ / θ measurement: the diverging slit was 1 °, the light receiving slit was 0.15 mm, and the scattering slit was 1 °. The results (average of 5 samples each) are also shown in Table 3.

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 detector is fixed to the 2θ value of the {111} _Cu surface of the sample, and any one of the four-fold symmetrical diffraction peaks obtained when the sample is β-axis scanned (β = 0 to 360 °). Was used to evaluate the half width (FWHM _{111} ) and the integral width (IW _{111} ), and the ratio (IW _{111} / FWHM _{111} ) was calculated. The results (average of 5 samples each) are also shown in Table 3.

The relationship of the crystal grain orientation state of the rolled copper foil before and after recrystallization annealing will be summarized. As is apparent from the results in Table 2, the rolled copper foil obtained by subjecting the rolled copper foil having the crystal grain orientation state as shown in FIG. 8 to recrystallization annealing is “{200} _Cu plane occupancy”, “IW _{{200 }} / FWHM _{200} ”and“ IW _{111} / FWHM _{111} ”, which indicates a cubic texture with extremely high triaxial orientation.

  In contrast, a rolled copper foil obtained by subjecting a rolled copper foil having a crystal grain orientation state as shown in FIGS. 9 to 11 to recrystallization annealing is inferior in one or more of the above three indices, and has a cubic texture. This indicates that the triaxial orientation of is inferior (inhibited).

(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 4.

  As is apparent from the results in Table 4, 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 (see Table 3) of the cubic texture in Example 1.

(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. 12 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 5.

  As is apparent from the results in Table 5, it can be seen that the rolled copper foil of Example 1 has a flex life (twice or higher flex characteristics) that is twice or more that of Comparative Examples 1 to 3. This result is considered to be caused by the extremely high triaxial orientation (see Table 3) and the large average crystal grain size (see Table 4) of the cubic texture in Example 1.

(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. 6, 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. For these rolled copper foils (final cold rolling finished), X-ray diffraction 2θ / θ measurement of the rolled surface and XRD pole figure measurement of the {111} _Cu surface based on the rolled surface were performed. The same results as in (a) and FIG. 8 were obtained.

The softening temperature of the produced rolled copper foil (Examples 2-3 and Comparative Example 4) was investigated. The investigation method was substantially based on the tensile test method of JIS Z 2241, and was determined by 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 6 shows the evaluation results of the average crystal grain size, and Table 7 shows the evaluation results of the bending characteristics.

  When considering the results in Tables 4 to 7 in total, 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).

In addition, the rolled copper foils of Examples 2 and 3 subjected to the heat treatment were subjected to XRD · 2θ / θ measurement, {200} _Cu surface rocking curve measurement, and the rolled surface as a reference, as in Example 1. When the in-plane orientation measurement by XRD pole figure measurement of {111} _Cu plane was performed, the {200} _Cu plane occupancy of 90% or more, 0.85 ≦ IW _{200} / FWHM _{200} ≦ 1.15, respectively. And 0.85 ≦ IW _{111} / FWHM _{111} ≦ 1.15.

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. 13 is an example of the XRD pole figure measurement result of the {111} _Cu plane based on the rolled surface in Comparative Example 4. FIG. 13A shows the normalized average intensity of the {111} _Cu plane diffraction peak obtained by β scanning at each α angle, and FIG. 13B shows a positive dot diagram.

  As is apparent from the results in the figure, 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 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 after a final cold rolling process and before recrystallization annealing. Example of results obtained by XRD pole figure measurement of {111} _Cu plane based on rolled surface in the rolled copper foil according to the present embodiment after the final cold rolling step and before recrystallization annealing It is. 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. 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 X-ray diffraction 2 (theta) / (theta) measurement result with respect to a rolling surface before recrystallization annealing after the last cold rolling process. 7A shows Example 1, FIG. 7B shows Comparative Example 1, FIG. 7C shows Comparative Example 2, and FIG. 7D shows Comparative Example 3. FIG. 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. 8A shows the normalized average intensity of the {111} _Cu surface diffraction peak obtained by β scanning at each α angle, and FIG. 8B 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. 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 2. 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 3. 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 a schematic diagram showing the outline of bending characteristic evaluation (sliding bending test). 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 4. FIG. 13A shows the normalized average intensity of the {111} _Cu plane diffraction peak obtained by β scanning at each α angle, and FIG. 13B shows a positive dot diagram.

Explanation of symbols

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

Claims (6)

As a result obtained by X-ray diffraction 2θ / θ measurement on the rolled surface in the rolled copper foil after the final cold rolling process and before recrystallization annealing, 80% or more of the diffraction peak of the copper crystal is the {220} _Cu surface. Yes,
In addition, when the normalized average intensity of {111} _Cu plane diffraction peaks obtained by β scanning at each α angle is plotted as a result obtained by X-ray diffraction pole figure measurement based on the rolled surface, the α angle The rolled copper foil is characterized in that the normalized average strength in a range of 35 to 75 ° is not stepped, or has a crystal grain orientation state in which only one maximum region exists. In the rolled copper foil which recrystallized and annealed with respect to the rolled copper foil of Claim 1, 90% or more of the diffraction peak of a copper crystal is a result obtained by the X-ray diffraction 2 (theta) / (theta) measurement with respect to the said rolling surface. {200} _Cu surface,
As a result obtained by X-ray diffraction rocking curve measurement of the {200} _Cu surface, the ratio of the half-value width (FWHM _{200} ) to the integral width (IW _{200} ) of the diffraction peak is 0.85 ≦ IW _{200} / FWHM _{200} ≦ 1.15,
And the result obtained by X-ray diffraction pole figure measurement with the rolled surface as a reference, the half-value of any one of the diffraction peaks of the {111} _Cu plane with respect to the {200} _Cu plane, among the four-fold symmetric diffraction peaks. Rolling having a grain orientation state in which the ratio of width (FWHM _{111} ) to integral width (IW _{111} ) is 0.85 ≦ IW _{111} / FWHM _{111} ≦ 1.15 Copper foil.   The rolled copper foil according to claim 2, wherein the average grain size of the recrystallized grains observed on the rolled surface is 40 µm or more.   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. As a result obtained by X-ray diffraction 2θ / θ measurement on the rolled surface in the rolled copper foil after the final cold rolling process and before recrystallization annealing, 80% or more of the diffraction peak of the copper crystal is the {220} _Cu surface. And when the normalized average intensity of the {111} _Cu plane diffraction peak obtained by β scanning at each α angle is plotted as a result obtained by X-ray diffraction pole figure measurement based on the rolled surface, The standardized average strength in the range of α angle of 35 to 75 ° is not stepped, or a method for producing rolled copper foil in which only one maximum region exists,
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%. 6. The manufacturing method according to claim 5, wherein in the final cold rolling step before recrystallization annealing, “degree of work in the first pass” ≧ “degree of work in the second pass” ≧ “degree of work in the third pass” ”And the degree of work after the third pass is controlled to 15 to 25%.

Images