TWI480397B - Rolled copper foil - Google Patents

Description

Calendered copper foil

The present invention relates to a rolled copper foil which can be preferably used for an FPC (Flexible Print Circuit).

The flexible printed circuit board (FPC) is manufactured by etching a copper foil laminated plate (CCL, Copper Clad Laminate) with a copper foil and a resin by etching to remove excess copper portions and performing circuit processing. As the copper foil for FPC, an electrolytic copper foil or a rolled copper foil is used, but in particular, a rolled copper foil is used in many applications where high flexibility is required. As a composition of the rolled copper foil, a tough-pitch copper, an oxygen-free copper, or a trace element added thereto may be used.

Further, in the production of CCL, the copper foil is heated and recrystallized, but usually the copper foil changes in size before and after recrystallization. Therefore, when the dimensional change rate of the copper foil is large, the copper foil is cooled and shrunk after the production of the CCL, and is deformed by applying shrinkage stress to the resin laminated with the copper foil. Thereafter, if the copper foil in the CCL is removed by etching in order to perform the above-described circuit processing, the shrinkage stress applied to the resin is removed to restore the resin to its original size. Therefore, for example, even if the size of the copper foil is 1 mm, the size of the FPC becomes larger than 1 mm when the resin is enlarged to the original size after etching, so that the dimensional stability of the FPC is lowered, and it is difficult to form a target shape. Or the case of a circuit of size.

In this case, a technique of recrystallizing the copper foil before the production of the CCL laminated with the resin is known (Patent Document 1). Also, a group of improved resins is also known. A technique for increasing the dimensional stability of the resin itself (Patent Document 2).

Patent Document 1: Japanese Laid-Open Patent Publication No. 2005-138310

Patent Document 2: Japanese Laid-Open Patent Publication No. 2008-290302

However, in the case of the technique described in Patent Document 1, if the crystal is recrystallized in advance, the strength of the copper foil is lowered, and the transfer of the surface of the roll when the resin is laminated or the press-fitting of foreign matter is likely to occur in the copper foil. Bad department. In addition, it is necessary to have a device for annealing the copper foil in advance, and the burden on the device is increased.

Further, in the case of the technique described in Patent Document 2, since it is limited to a special resin, it is not possible to select a resin having an appropriate property depending on the use of the FPC, and the application range is narrow, and the cost is involved.

That is, the present invention has been made to solve the above problems, and an object of the invention is to provide a rolled copper foil which has a small dimensional change before and after recrystallization and which has a small anisotropy in dimensional change.

The inventors of the present invention conducted various studies and found that the dimensional change before and after recrystallization is reduced by adjusting the degree of processing of each pass in the final cold rolling.

In order to achieve the above object, the dimensional change rate of the rolled copper foil of the present invention before and after annealing at 350 ° C for 30 minutes is 0 to 0.01% in the direction parallel to the rolling direction and the direction perpendicular to the rolling direction.

Preferably, the area ratio of the recrystallized structure is less than 50% (including 0%) before annealing at 350 ° C for 30 minutes, and the area ratio of the recrystallized structure is 50% after annealing at 350 ° C for 30 minutes. the above.

From the above-mentioned calendered parallel section observed at 350 ° C for 30 minutes, The number of the shear bands reaching the surface from the surface of the copper foil in the thickness direction is 1 μm, and the number of the shear bands reaching the surface is preferably 0.1 strip/μm or less based on the total of the front and back surfaces.

In the above final cold rolling, it is preferred that the processing degree is higher than the previous pass in the final 5 passes, and the maximum processing degree of any of the 5 passes exceeds 40%, and the processing in the final pass is performed. Degree is the smallest of the above 5 passes.

Preferably, after the ingot is subjected to hot rolling, the cold rolling and annealing are repeated, and finally, the final cold rolling is performed, and the total degree of the final cold rolling is 98.5% or less.

According to the present invention, a rolled copper foil having a small dimensional change before and after recrystallization and a small anisotropy of dimensional change can be obtained.

Hereinafter, the rolled copper foil according to the embodiment of the present invention will be described. In addition, in the present invention, the % is considered to represent the mass % unless otherwise specified.

<Dimensional change rate>

The dimensional change rate of the rolled copper foil of the present invention before and after annealing at 350 ° C for 30 minutes is 0 to 0.01% in the direction parallel to the rolling direction and the direction perpendicular to the rolling direction. The dimensional change is due to recrystallization. The copper foil is recrystallized by the heat treatment in the FPC manufacturing step. Therefore, if the dimensional change before and after annealing at 350 ° C for 30 minutes is small, the dimensional stability of the FPC is improved. Further, heating at 350 ° C for 30 minutes simulates the step of laminating the resin on the copper foil.

<composition>

As a component composition of the copper foil, copper (TPC, Tough-pitch Copper) or JIS-H3100 (alloy No. C1020) oxygen-free copper (OFC, Oxygen Free) prescribed by JIS-H3100 (alloy No. C1100) can be preferably used. Copper).

Further, the copper or oxygen-free copper may be contained in a total amount of 20 to 1500 ppm by mass selected from the group consisting of Ag, Sn, In, Ti, Zn, Zr, Fe, P, Ni, Si, Te, Cr, and Nb. One or more of the groups composed of V and V are more preferably contained in an amount of 20 to 1000 ppm by mass. For example, it may contain 10 to 500 ppm by mass of Sn, and/or 10 to 500 ppm by mass of Ag as an additive element with respect to the above-mentioned refined copper or oxygen-free copper.

When the total content of the above elements is less than 20 ppm by mass, the softening temperature is low and the storage property at normal temperature is lowered. In addition, when the total content of the above elements exceeds 1000 ppm by mass, it is difficult to make the area ratio of the recrystallized structure of the rolled copper foil 50% or more after annealing at 350 ° C for 30 minutes, and the dimensional change ratio of the rolled copper foil exceeds 0.01. % is getting bigger.

Further, since the rolled copper foil for FPC is required to have flexibility in many cases, the thickness of the rolled copper foil is preferably 20 μm or less. Further, the lower limit of the thickness of the rolled copper foil is not particularly limited. However, the thickness of the rolled copper foil is preferably 4 μm or more, more preferably 5 μm or more, and still more preferably 6 μm or more in consideration of manufacturability and the like.

<recrystallized structure>

After annealing at 350 ° C for 30 minutes, the area ratio of the recrystallized structure is preferably 50% or more, more preferably 70% or more, further preferably 80% or more, and still more preferably 90% or more. The dimensional change is due to recrystallization, because If it is not recrystallized after annealing at 350 ° C for 30 minutes, there is no dimensional change. However, if the area ratio of the recrystallized structure is less than 50% after annealing at 350 ° C for 30 minutes, the bendability of the copper foil may not be obtained, and the characteristics required as CCL may not be obtained.

In addition, when the rolled copper foil having an area ratio of the recrystallized structure of 50% or more before annealing at 350 ° C for 30 minutes is used, the strength of the rolled copper foil is low and it is difficult to use. Therefore, before annealing at 350 ° C for 30 minutes, the area ratio of the recrystallized structure is preferably less than 50% (including 0%), more preferably less than 30% (including 0%), and even more preferably less than 20%. % (including 0%), and more preferably less than 10% (including 0%).

Further, in general, when the rolled copper foil having an area ratio of the recrystallized structure before annealing at 350 ° C for 30 minutes is annealed at 350 ° C for 30 minutes and the area ratio of the recrystallized structure is 50% or more, calendering is performed. The dimensional change rate of the copper foil becomes larger than 0.01%.

Therefore, by adjusting the degree of processing of each pass in the final cold rolling as described below, the dimensional change before and after recrystallization becomes 0 to 0.01% in the direction parallel to the rolling direction and the direction perpendicular to the rolling, and the anisotropy of the dimensional change small.

Further, the area ratio of the recrystallized structure is electrolytically polished on the surface of the copper foil, and the crystal grains surrounded by the clear grain boundary in the SEM (Scanning Electron Microscope) image are regarded as recrystallized grains. The area ratio (%) of the recrystallized grains in the observed area was calculated from image analysis. Image analysis uses commercially available image analysis software. Further, the observation field of view is set to 500 μm × 500 μm or more.

Moreover, if it is annealed at 350 ° C for 30 minutes, it does not recrystallize. The extremely high copper foil lacks flexibility and is not suitable for CCL use. Therefore, in the present invention, it is preferable to anneal at 350 ° C for 30 minutes and then have a recrystallization ratio of 50% or more.

<Shear band>

From the above-mentioned calendering parallel cross section before annealing at 350 ° C for 30 minutes, the shearing tape reaching the surface from the surface of the copper foil in the thickness direction is preferably 1 line/μm. the following.

If the metal material is subjected to calendering, it will cause sliding deformation. However, if it is deformed due to high workability, uneven deformation due to plastic instability will occur, and a shear band will be generated. The shear band refers to a thin planar structure that is inclined by 30 to 60 degrees with respect to the surface of the rolled plate (for example, "Iron and Steel" 70th (1984) No. 15 P.18). The shear band has a crystal orientation that is substantially similar to the surrounding mother phase, but has a tight cell structure that tends to cause recrystallization nucleation. Therefore, in the material developed by the shear band, recrystallization of the shear band portion and the parent phase occurs unevenly, and as a result, the development of the recrystallization texture is hindered. Further, since the shear band is developed in the direction parallel to the rolling to cross the thickness of the copper foil, anisotropy occurs in the parallel direction of rolling and the right angle of rolling. Therefore, the anisotropy can be reduced by reducing the shear band to 0.1 strips/μm or less.

As a method of making the shear band 0.1 strip/μm or less, the following method may be mentioned: the processing degree is higher than the previous pass in the final 5 passes of the final cold rolling described below, and the final pass is performed. The degree of processing is set to be the smallest of the final 5 passes.

<Measurement of shear band>

The measurement of the shear band is performed by polishing the cross section R of the copper foil in the parallel direction RD, and the width of the field of view RD in the RD direction is W=200 μm or more, and the thickness t of the copper foil is determined as the observation field of the height. V, an image of a scanning electron microscope (SEM) was obtained. Further, the number of the shear bands Sh reaching the surface of the copper foil from the line C of the surface of the copper foil in the thickness direction by 1 μm is divided by the width W of the field of view in the RD direction as the number of shear bands ( Bar / μm). Further, since the line C can be drawn from the front and back sides of the copper foil, the number of the shear bands is set to the total value of the values measured on the front and back of the copper foil.

Furthermore, it is obvious that the shear band has one end of the Sh line reaching the surface of the copper foil, the other end intersecting the line C, and the shear band (the shear band that does not reach the surface of the copper foil or intersects with the line C) The influence of the development of the recrystallized texture is small, so it is not counted as a shear band in the present invention.

<Determining the shear band>

The shear band is formed by the shear deformation of the surface which is inclined by 30 to 60 degrees with respect to the rolling surface due to the plastic instability caused by the strong processing, and the formed structure appears on the observation surface. Therefore, the shear band is observed as a discontinuous surface of the calendered structure. Since the crystal orientation of the shear band portion is not different from that of the parent phase, the shear band cannot be specified by the crystal orientation measurement. On the other hand, since the shear band is expanded in the depth direction, the cross section of the material can be observed and determined. Therefore, when the cross section of the copper foil after the final rolling is parallelized in the parallel direction, the discontinuous portion of the rolled structure inclined by 30 to 60 degrees with respect to the rolling surface is used as a shear band. Specifically, an image of a microscope (a metal microscope, a scanning electron microscope (SEM), a scanning ion microscope (SIM), or the like) that obtains the above cross section can be obtained by A line which is inclined by 30 to 60 degrees with respect to the rolling surface is determined as a shear band by analysis or visual observation. The cross-sectional processing of the copper foil is preferably performed by FIB (Focused Ion Beam) or CP (Cross-section Polisher), but methods such as mechanical polishing may also be used.

Fig. 2 shows an SEM image of the structure when viewed from a cross section in the direction parallel to the calendering. In the figure, the line connecting the two arrows indicated by the symbol Sh is a shear line that crosses the line C and reaches the surface of the copper foil. Further, the white arrow is a shear band that does not reach the line C.

Next, an example of a method for producing a rolled copper foil of the present invention will be described. First, an ingot composed of copper and a necessary alloying element, and further an inevitable impurity, is subjected to hot rolling, and then cold rolling and annealing are repeated, and finally, a specific thickness is formed by final cold rolling.

Here, the total degree of work of the final cold rolling is preferably 98.5% or less, more preferably 98.3% or less. Further, the total degree of processing of the final cold rolling is preferably 90% or more, more preferably 95% or more. Further, in the final cold rolling, the setting is performed in the following manner: in the final 5 passes, the processing degree is higher than the previous pass, and the maximum processing degree of any of the 5 passes except the final pass is More than 40%, and the processing degree in the final pass is the smallest of the above 5 passes.

In this way, the total degree of final cold rolling is set to 98.5% or less, whereby the development of the shear band can be suppressed. Moreover, in the final 5 passes, the degree of processing is higher than that of the previous pass, and the maximum degree of processing of any pass except the final pass is set to 40% or more, thereby making the copper foil in the thickness direction. The deformation is uniformly deformed to suppress local deformation, and the development of the shear band can be prevented. Also borrow By rolling the final pass at a lower degree of processing, it is possible to suppress the occurrence of a sheared working layer on the surface of the material, and to reduce the anisotropy of the material properties (size change).

Furthermore, if the total degree of processing of the final calendering is less than 90%, it is difficult to anneal at 350 ° C for 30 minutes when the area ratio of the recrystallized structure of the rolled copper foil is less than 50% before annealing at 350 ° C for 30 minutes. The area ratio of the recrystallized structure of the rolled copper foil thereafter is 50% or more.

Example

The ingot was cast by adding the elements described in Table 1 to the refined copper (TPC) or JIS-H3100 (alloy No. C1020) oxygen-free copper (OFC) prescribed by JIS-H3100 (alloy No. C1100). The ingot to be produced is hot-rolled to a thickness of 10 mm at a temperature of 800 ° C or higher, and after the surface of the oxidized scale is cut, the cold rolling and annealing are repeated, and then the thickness is finally formed by final cold rolling. 0.006~0.017mm. Further, Examples 1, 3, 5, 7 to 9, 11 to 15, and Comparative Examples 1 to 3 have a thickness of 0.012 mm, Example 2 has a thickness of 0.006 mm, and Example 4 has a thickness of 0.017 mm. In Example 6, the thickness was set to 0.009 mm.

Furthermore, the final cold rolling was carried out by 10 to 15 passes, and the total degree of final cold rolling was set to the value shown in Table 1. Further, the respective processing degrees of the final 5 passes of the final cold rolling were set to the values shown in Table 1. The degree of processing is obtained by the following formula.

(Processing degree) = {(thickness before rolling) - (thickness after rolling)} / (thickness before rolling) × 100 (%)

Further, Example 9 was heated at 350 ° C for 30 minutes after the final cold rolling. Example 15 was carried out at 100 ° C for 5 hours after the final cold rolling. heat.

Each of the copper foil samples obtained in this manner was evaluated for various characteristics.

(1) Dimensional change rate

Each copper foil sample was cut into strips having a width of 15 mm and a length of 120 mm, and the interval of 100 mm was marked with two punctuation marks. After the distance L0 between the punctuation points was measured, the copper foil was annealed at 350 ° C for 30 minutes in an Ar gas flow environment, and the distance L between the punctures after annealing was measured. The dimensional change rate (thermal expansion ratio) is an absolute value of a value obtained by the following formula. Furthermore, since the copper foil sample shrinks after annealing, the value of the dimensional change rate is negative.

(Dimensional change rate)=|{(L-L0)/L0}×100(%)|

(2) Area ratio of recrystallized structure

For the obtained sample, after annealing at 350 ° C for 30 minutes and annealing at 350 ° C for 30 minutes, the surface of the sample was subjected to electrolytic polishing, and the SEM (Scanning Electron Microscope) image was surrounded by a clear grain boundary. The crystal grains were regarded as recrystallized grains, and the area ratio of the recrystallized grains in the observation area was calculated by image analysis. Further, in Example 9, the area ratio of the recrystallized grains was measured not after the final heating at 350 ° C for 30 minutes, but after annealing at 350 ° C for 30 minutes. The image analysis system uses a commercially available image analysis software (software name "ImageNos", which can be binarized by the free software available on the following website).

Http://www.geocities.jp/baruth0/software.html

Http://www.vector.co.jp/soft/win95/art/se065425.html

Further, the area ratio is calculated using a commercially available software (software name "PixelCounter s", which can be obtained by the free software available on the following website).

Http://www.vector.co.jp/soft/win95/art/se385899.html

Further, the observation field of view is set to 500 μm × 500 μm or more. The area ratio of the recrystallized structure was determined by the following formula.

(area ratio of recrystallized structure) = (area of recrystallized grains) / (area of observation field) × 100 (%)

(3) Number of shear bands (total value of the back of the watch) (frequency)

As shown in Fig. 1, the sample R before the annealing at 350 ° C for 30 minutes is subjected to grinding (mechanical polishing or CP (ion beam section polishing)), and the width of the field of view in the RD direction is W = Above 200 μm, the thickness t of the copper foil was determined as the observation field of view V of the height, and an image of a scanning electron microscope (SEM) was obtained. Further, the number of the shear bands Sh reaching the surface of the copper foil from the line C of the surface of the copper foil in the thickness direction by 1 μm is divided by the width W of the field of view in the RD direction as the number of shear bands ( Bars / μm) and counted by visual inspection. Further, regarding Example 9, a copper foil sample which was heated at 350 ° C for 30 minutes after the final cold rolling (that is, with respect to Example 9, after heating at 350 ° C for 30 minutes after the final cold rolling, further proceeded to the second The film was annealed at 350 ° C for 30 minutes, but this was the first time after heating at 350 ° C for 30 minutes, and the number of shear bands was measured in the same manner as above.

Furthermore, the line C is drawn from the back surface of the copper foil, and the number of shear bands is measured on the front and back sides of the copper foil, respectively, by {(the number of shear bands on the surface) + (the shear band on the back side) The number of strips)} ÷ RD direction of the field of view width W to find the number of strips.

(4) Flexibility

After the sample was heated at 350 ° C for 30 minutes to recrystallize, the bending fatigue life was measured by the bending test apparatus shown in FIG. 3 . This device has a structure in which the vibration transmitting member 3 is coupled to the oscillation driving body 4, and the portion of the screw 2 to be tested indicated by the arrow and the front end portion of the vibration transmitting member 3 are fixed to the device at four points. When the vibration transmission member 3 is driven up and down, the intermediate portion of the copper foil 1 is bent into a hairpin shape with a specific radius of curvature r. In this test, the number of times until the fracture was repeated under the following conditions was determined.

Further, in the case where the sheet thickness is 0.012 mm, the test conditions are as follows: test piece width: 12.7 mm, test piece length: 200 mm, test piece taking direction: in the manner that the length direction of the test piece is parallel to the rolling direction Taken, radius of curvature r: 2.5 mm, vibration stroke: 25 mm, vibration speed: 1500 times / minute. In addition, when the bending fatigue life was 30,000 or more, it was judged that the bending property was excellent, and it was set to "○". Moreover, when the bending fatigue life is less than 30,000 times, the bending property is set to "x".

Further, in the case where the sheet thicknesses are 0.017 mm, 0.009 mm, and 0.006 mm, respectively, the curvature radius r is changed to 3.8 mm, 2 mm, and 1.3 mm, respectively, so that the bending deformation is the same as the bending test in the case where the thickness is 0.012 mm. , but other test conditions are set to the same.

(5) foilability

The polyimine resin was coated and dried on the surface of the copper foil, and then heated at 200 ° C for 30 minutes to prepare a CCL laminate by a casting method. The CCL obtained was visually observed to be 100 m in length. In the case where the CCL has a wrinkle having a length of 10 cm or more, it is set to "X", and there will be no pleats having a length of 10 cm or more. The wrinkle situation is set to "○".

The results obtained are shown in Table 1. Further, "190 ppm Ag-TPC" in the column of the composition of Table 1 means that 190 wtppm of Ag was added to the refined copper (TPC) of JIS-H3100 (alloy No. C1100). Further, "80 ppmSn-OFC" in the column of the composition of Table 1 means that 80 wtppm of Sn is added to the oxygen-free copper (OFC) of JIS-H3100 (alloy No. C1020).

As can be seen from Table 1, in the case of each of the examples, the dimensional change rate before and after annealing at 350 ° C for 30 minutes was 0 to 0.01% in both the rolling parallel direction and the rolling orthogonal direction. Further, in the case of each of the examples except the example 9, the area ratio of the recrystallized structure before annealing at 350 ° C for 30 minutes was less than 50%, and the foil-passing property was excellent. In the case of each of the examples except the examples 7 and 8, the area ratio of the recrystallized structure after annealing at 350 ° C for 30 minutes was 50% or more, and the flexibility was excellent. Further, in the case of each of the examples, the shearing band which reached the surface by transverse line C was 0.1 strip/μm or less as observed from the rolling parallel section before annealing at 350 ° C for 30 minutes.

Further, in the case of Example 7 in which the concentration of the additive element exceeds 1000 ppm, it is not recrystallized after annealing at 350 ° C for 30 minutes, and the area ratio of the recrystallized structure after annealing at 350 ° C for 30 minutes is less than 50%. Obtain the flexibility necessary for FPC. However, it is useful in FPC applications (FPC for substrates for LEDs or FPCs for liquid crystal displays, which are used once, without repeated bending) for FPC applications that do not require high flexibility. No problem on it.

Moreover, in the case of Example 8 in which the total degree of final cold rolling was less than 98.5%, it was not recrystallized after annealing at 350 ° C for 30 minutes, and the area ratio of the recrystallized structure after annealing at 350 ° C for 30 minutes was not reached. 50%, the bendability necessary for FPC cannot be obtained. However, when used in an FPC application (an FPC for a substrate for LEDs or an FPC for a liquid crystal display (used once, without repeated bending)), etc., There is no problem in practical use.

Further, in the case of Example 9 which is further annealed after the final cold rolling In the case of annealing at 350 ° C for 30 minutes, the area ratio exceeds 50%, and the foilability during casting is inferior. However, if the foil speed is slowed down, the productivity is lowered, but there is no problem in practical use.

On the other hand, in the case of Comparative Example 1 in which the total degree of processing of the final cold rolling exceeds 98.5% and the maximum degree of processing of any of the final 5 passes of the final cold rolling is less than 40%, the shear band exceeds 0.1 strip/μm, the dimensional change rate of the rolling right angle direction before and after annealing at 350 ° C for 30 minutes exceeded 0.01%.

When the total degree of processing of the final cold rolling exceeds 98.5%, and the degree of processing in the final pass of the final cold rolling is not the smallest of the 5 passes, the shear band exceeds 0.1 strip/μm to 350 ° C. The dimensional change rate in the direction perpendicular to the rolling direction after annealing for 30 minutes exceeded 0.01%. Further, if the number of the shear bands is large, the microstructure in the parallel direction and the right-angle direction of the rolling is different, and the dimensional change rate in the direction perpendicular to the rolling is particularly large.

Further, in Table 1, the total value of the front and back surfaces of the shear band which reaches the surface from the center line of the copper foil in the thickness direction is also indicated. In the case of Comparative Examples 1 to 3, although the length of the shear band reaching the center in the thickness direction was small, it was found that the number of shear bands present in the portion closer to the surface of the copper foil increased.

In the final cold rolling, in the case of Comparative Example 3 in which the degree of processing is higher than the previous pass (ie, the degree of processing is monotonously decreasing toward the final pass) in the final 5 passes, the shear band is more. The anisotropy of the dimensional change becomes large.

T‧‧‧ Thickness of copper foil

C‧‧‧Center line of thickness direction

Sh‧‧‧Shear band

V‧‧‧ observation field

RD‧‧‧Rolling parallel direction of ground copper foil

R‧‧‧A section of the calendered parallel direction RD of the ground copper foil

Width of field of view in the direction of W‧‧‧RD

1‧‧‧Tested copper foil

2‧‧‧ screws

3‧‧‧Vibration transfer member

4‧‧‧Oscillation driver

Fig. 1 is a view showing a method of measuring the number of shear bands.

Fig. 2 is a view showing an SEM image of a structure when viewed from a cross section in a parallel direction of rolling.

Fig. 3 is a view showing a method of measuring the bending fatigue life by a bending test device.

T‧‧‧ Thickness of copper foil

C‧‧‧Center line of thickness direction

Sh‧‧‧Shear band

Claims (9)

A rolled copper foil having a dimensional change rate before and after annealing at 350 ° C for 30 minutes is 0 to 0.01% in both the parallel direction of rolling and the direction perpendicular to rolling. The rolled copper foil of claim 1, wherein the area ratio of the recrystallized structure is less than 50% (including 0%) before annealing at 350 ° C for 30 minutes, and after annealing at 350 ° C for 30 minutes. The area ratio of the recrystallized structure is 50% or more. The rolled copper foil according to claim 1 or 2, wherein the rolled parallel cross section from the above-mentioned annealing at 350 ° C for 30 minutes is observed, and the surface of the copper foil is transversely cut to a depth of 1 μm in the thickness direction. The number of the shear bands on the surface is 0.1 pieces/μm or less based on the total value of the front and back sides. The rolled copper foil according to any one of claims 1 to 2, wherein in the final cold rolling, the degree of processing is higher than the previous pass in the final 5 passes, in the 5 passes The maximum degree of processing of any pass exceeds 40%, and the degree of processing in the final pass is the smallest of the above 5 passes. For example, the rolled copper foil of the third application patent scope, in the final cold rolling, the processing degree is higher than the previous pass in the final 5 passes, and the maximum processing degree of any of the 5 passes exceeds 40%, and the processing degree in the final pass is the smallest of the above 5 passes. For example, in the rolling copper foil of claim 1 or 2, the ingot is subjected to hot rolling, repeated cold rolling and annealing, and finally final cold rolling is performed, and the final cold rolling is performed. The degree of processing is 98.5% or less. For example, in the case of the rolled copper foil of claim 3, the ingot is carried out. After hot rolling, the cold rolling and annealing are repeated, and finally, the final cold rolling is performed, and the final cold rolling has a total working degree of 98.5% or less. For example, the rolled copper foil of the fourth application patent scope is obtained by subjecting the ingot to hot rolling, repeating cold rolling and annealing, and finally performing final cold rolling, and the final cold rolling has a total working degree of 98.5. %the following. For example, in the rolling copper foil of claim 5, after the ingot is subjected to hot rolling, the cold rolling and annealing are repeated, and finally the final cold rolling is performed, and the final cold rolling has a total working degree of 98.5. %the following.