TW201315549A - Rolled copper foil - Google Patents

Abstract

To provide a rolled copper foil for which ease of handling is improved by moderately roughening the surface of the copper foil, and which has excellent flexibility and good surface etching characteristics. For this rolled copper foil: in a state in which the rolled copper foil has a 60 DEG gloss (G60RD) at the surface, as measured parallel to the rolling direction, of 100 to 300, and is thermally refined to a recrystallized structure by heating for 30 minutes at 200 DEG C, the (200) plane diffraction intensity, obtained according to X-ray diffraction of the rolled surface, with respect to the (200) plane diffraction intensity (I0) obtained by X-ray diffraction of fine copper powder is 20 <= I/I0 <= 40; on three straight lines that are 175 mum long in the direction parallel to the rolling direction, and are at least 50 mum apart from each other in a direction perpendicular to the rolling direction, at the surface of the copper foil, the ratio (d/t) of the average value (d) of the difference between the minimum height and the maximum height of each straight line in the thickness direction, which corresponds to the maximum depth of an oil pit, and the thickness (t) of the copper foil, is not more than 0.1; and the ratio (G60RD/G60TD) between the 60 DEG gloss (G60RD) at the surface, as measured parallel to the rolling direction, and a 60 DEG gloss (G60TD) at the surface, as measured perpendicular to the rolling direction, is less than 0.8.

Description

Calendered copper foil

The present invention relates to a rolled copper foil which can be preferably used for FPC requiring flexibility.

Copper foil for FPC (flexible printed circuit board) for bending requires high flexibility. A method for imparting flexibility to a copper foil by a method of improving the crystal orientation of the (200) plane of the rolled surface of the copper foil (Patent Document 1) and a technique for increasing the crystal grain ratio in the thickness direction of the copper foil (Patent Document 2) A technique in which the surface roughness Ry (maximum height) corresponding to the depth of the oil pit of the copper foil is reduced to 2.0 μm or less (Patent Document 3).

The usual FPC manufacturing steps are as follows. First, a copper foil is bonded to a resin film. The joining method includes a method of imidating ytterbium by applying heat treatment to a varnish applied to a copper foil, or a method of laminating a resin film with an adhesive attached to a copper foil. The copper foil with a resin film joined by these steps is called CCL (Copper Cladding Laminate). The copper foil is recrystallized by the heat treatment in the CCL manufacturing step.

However, when FPC is produced using a copper foil, if the surface of the copper foil is etched in order to improve the adhesion to the coating film, a depression having a diameter of about 10 μm is formed on the surface (disc type sinking), and in particular, high bending copper is likely to be generated. Foil. The reason for this is considered to be that the crystal orientation of the copper foil is controlled so as to expand the cubic structure after recrystallization annealing in order to impart high flexibility. In other words, it is considered that even if the above control is performed, all the crystal orientations do not coincide, and crystal grains having different crystal orientations are locally present in the uniform structure. At this time, because The etch rate is different for the crystal face to be etched, and the grain is partially etched to be deeper than the periphery to cause a depression. This depression is a cause of lowering the etching property of the circuit, determining that the appearance is poor when the appearance is inspected, and lowering the yield.

Further, depending on the etching liquid, there is a case where the etching speed of the cubic structure is faster than that of the random structure and the etching rate is slow. Therefore, when the cubic structure after the recrystallization annealing is excessively expanded, if the etching speed of the cubic structure is slow, the productivity is lowered, or copper remains between the circuits at the time of circuit formation, and the etching property is deteriorated. On the other hand, if the etching speed of the cubic structure becomes fast, it becomes easy to be etched to the circuit portion, and the etching property tends to deteriorate.

In the method of reducing the above-described depression, there is reported the following technique (Patent Document 4): before the rolling or after rolling, the surface of the copper foil is mechanically polished to impart strain to the work-affected layer, and then recrystallized. According to this technique, by processing the metamorphic layer, the uneven crystal grains are clustered on the surface after recrystallization, so that crystal grains having different crystal orientations are not separately present.

[Patent Document 1] Japanese Patent No. 3009383

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2006-117977

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2001-058203

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2009-280855

However, in the case of the technique described in Patent Document 4, there are many problems in that the crystal grains on the surface of the copper foil are not oriented on the (100) plane because the crystal grains are not uniform, and the bendability is lowered.

On the other hand, it is understood that although it is necessary to ensure the adhesion of the copper foil to the roll at the time of manufacture, or to facilitate the operation of the copper foil product, the finalization will be carried out. The cold rolling delay increases the roughness of the roll to roughen the surface of the copper foil. However, if the surface of the copper foil is roughened, the degree of orientation of the crystal on the surface of the copper foil is lowered, resulting in poor bendability or easy to produce a dish. Type subsidence.

In other words, 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 surface roughness of a copper foil which is moderately roughened to improve workability, is further excellent in flexibility, and has excellent surface etching characteristics.

The inventors of the present invention have conducted various studies and found that the surface of the copper foil is not roughened before the final pass of the final cold rolling, and the surface of the copper foil is roughened in the final pass of the final cold rolling. Thereby, the surface of the final copper foil can be roughened, the shear deformation zone can be reduced, the bendability can be maintained, the dish shape is less depressed, and the difference in etching speed caused by the etching liquid becomes small, so It is an excellent copper foil for etching.

In order to achieve the above object, the rolled copper foil of the present invention has a 60-degree gloss G60 _RD of 100 or more and 300 or less according to JIS-Z8741, and is heated at 200 ° C for 30 minutes to be recrystallized. In the state of the structure, the diffraction intensity (I) of 200 obtained by X-ray diffraction of the calendering surface is 20 ≦I/ with respect to the diffraction intensity (I ₀ ) of X-ray diffraction by the micro-powder copper. I ₀ ≦40, the length of the copper foil in the direction parallel to the rolling parallel direction is 175 μm, and on the three straight lines separated by 50 μm or more in the direction perpendicular to the rolling direction, the maximum height and the minimum height in the thickness direction of each straight line corresponding to the maximum depth of the oil pit The ratio d/t of the average value d of the difference to the thickness t of the copper foil is 0.1 or less, and the 60 degree gloss G60 _RD of the surface measured in the parallel direction of rolling and the surface measured in the direction perpendicular to the rolling direction are based on JIS- The ratio of 60 degree gloss G60 _TD of Z8741 G60 _RD /G60 _{TD is} less than 0.8.

When the surface of the copper foil after the heat treatment at 200 ° C for 30 minutes is observed by EBSD after electrolytic polishing, it is preferable that the area ratio of the crystal grain of the rolling surface to the angle of [100] is 15 degrees or more. ~70%.

After the ingot is hot rolled, it is repeatedly subjected to cold rolling and annealing, and finally to final cold rolling. In the final cold rolling step, preferably in the first pass before the final pass, in the parallel direction of rolling. The measured 60 degree gloss of the surface G60 _RD exceeded 300.

According to the present invention, it is possible to obtain a rolled copper foil in which the surface of the copper foil is appropriately roughened to improve workability, excellent in flexibility, and excellent in surface etching characteristics.

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

First, the technical idea of the present invention will be described. When the roughness of the roll in the final cold rolling is increased and the surface of the copper foil is roughened, the handleability of the copper foil is improved, but the dishing is liable to occur, and the etching property is lowered. The reason for this is considered to be that a shear deformation band is generated in the thickness direction of the copper foil by finally cold rolling the rough roll, and the rolling deformation is continued, and the shear deformation band is elongated.

On the other hand, a method of improving the gloss (surface roughness) in order to obtain the bendability of the copper foil has been known from the prior art. It is considered that this method consists in that the final cold rolling is performed by using a roll having a low roughness, so that the shear deformation band is not easily generated in the thickness direction of the copper foil. However, if the gloss of the copper foil is increased (the surface roughness is made small), the handleability of the copper foil is lowered.

In contrast, the inventors discovered that the final cold rolling can be achieved. The surface of the copper foil is not roughened before the pass (for example, rolling with a roll having a low roughness), and the surface of the copper foil is roughened in the final pass of the final cold rolling (for example, using a rough roll) Calendering), the surface of the final copper foil is roughened, and the shear deformation zone is reduced, and the bendability is improved, and the surface etching property is improved.

That is, it has been previously considered that the orientation of the copper foil is purely dependent on the roughness of the surface of the copper foil, but it is actually known that the scale of the shear deformation zone inside the material affects the etching property and the degree of orientation (and dishing). Moreover, in the final cold rolling, if the expansion of the shear band can be sufficiently suppressed in the pass before the final pass, even if the surface of the copper foil is finished to be rough in the final pass, etching can be obtained. Good degree of orientation.

However, the degree of expansion of the above shear band cannot be clearly known only from the gloss value that has been used before. That is, it is considered that if the surface of the final copper foil is roughened and the shear deformation zone is reduced, the oil pit is shallow and has a certain width, and the frequency of occurrence of the oil pit is reduced (refer to Fig. 1 (a) It is difficult to express in the gloss of the rolling parallel direction RD perpendicular to the sump direction. On the other hand, if the crater has a certain width from the TD in the right angle direction, it is easy to know the change in the shape or frequency of the sump compared to the parallel direction.

The relationship between the above oil pit and glossiness will be described with reference to Fig. 1 .

First, Fig. 1(a) is a view showing the relationship between the oil sump and the glossiness of the example of the present invention. If the gloss G _RD is measured along the rolling parallel direction _RD , the direction of the reflected light in the oil sump is changed without being It was detected that the gloss was lowered. On the other hand, when the gloss G _TD is measured along the right angle direction TD, since the oil sump extends along the TD, even if the direction of the reflected light is shifted toward the lateral direction (RD direction) in the sump, it can be detected. Out, the gloss is improved. That is, G _{TD is} relatively higher than G _RD , and when 60 degree gloss is described later, the relationship of G60 _RD /G60 _TD <0.8 is satisfied.

Next, Fig. 1(b) is a view showing the relationship between the oil pit and the glossiness of the prior art in the case where the surface of the copper foil is rough, the surface of the copper foil becomes excessively rough, and the depth and length (generation frequency) of the oil pit are increased even if The gloss was measured in either of the rolling parallel direction RD and the rolling orthogonal direction TD, and the oil crater was not detected due to the change in the direction of the reflected light, and the gloss was lowered. In this case, G _{TD is} relatively lower than G _RD , and when the 60-degree glossiness described later is measured, the relationship of G60 _RD /G60 _TD >1 is satisfied.

On the other hand, Fig. 1(c) is a view showing the relationship between the oil pit and the glossiness of the prior art in the case where the surface of the copper foil is smooth, since the surface of the copper foil becomes too smooth, the oil pit becomes too shallow, so even along the parallel with the rolling direction RD _RD G gloss was measured, also because the pit in the direction of the reflected light oil that it becomes easy to change, enhance gloss. In other words, G _{RD is} relatively higher than G _TD . Therefore, when the 60-degree gloss degree described later is measured, the relationship of G60 _RD /G60 _TD is close to 1 (that is, the anisotropy of RD and TD becomes small). However, as shown in Fig. 1(b) of the previous example in which the surface of the copper foil is rough, since the surface of the copper foil is not rough, G60 _RD / G60 _TD <1 is obtained.

Next, the specification and composition of the rolled copper foil of the present invention will be described.

(1) Gloss G60 _RD

The 60° gloss G60 _RD of the surface measured in the rolling parallel direction _RD is 100 or more and 300 or less. When the G60 _RD exceeds 300, the surface of the copper foil becomes too smooth, and the adhesion to the roll at the time of manufacture of the copper foil is lowered, or the operation of the copper foil product is difficult. On the other hand, when the G60 _{RD is} less than 100, the surface of the copper foil becomes too rough, and the shear deformation band spreads inside the material, which tends to cause dishing, and the etching property is lowered.

(2) G60 _RD / G60 _TD

As described above, the surface of the copper foil is not roughened by the final pass of the final cold rolling, and the surface of the copper foil is roughened in the final pass of the final cold rolling, so that the final copper foil is The surface becomes thicker, and the shear deformation zone is reduced, and the bending property is maintained, and the dish type is reduced. Further, it has been found by the experiment of the present inventors (the examples described later) that the surface having such a small shear deformation band becomes G60 _RD /G60 _TD <0.8. Therefore, the ratio G60 _RD /G60 _TD of the 60° gloss G60 _RD of the surface measured in the direction of the rolling parallel direction and the 60° gloss G60 _TD of the surface measured in the direction perpendicular to the rolling direction is set to be less than 0.8. Furthermore, the ratio is used to offset the effects of overall gloss.

When G60 _RD /G60 _TD ≧0.8 is used, as described above with reference to Fig. 1(b), the surface of the copper foil becomes too smooth, resulting in a decrease in adhesion to the roll during the production of the copper foil, or a copper foil product. Operation is difficult. Further, as described in FIG. 1(c) above, when G60 _RD /G60 _TD >1, the surface of the copper foil becomes too rough, and the shear deformation band expands, and the bendability is lowered or becomes easy to occur. The dish is sunken.

Furthermore, the method of achieving G60 _RD /G60 _TD <0.8 is in the final cold rolling described above, and the expansion of the shear band is inhibited before the final pass, that is, before the final pass of the final cold rolling. In the meantime, rolling may be performed using a roll having a small roughness (surface roughness Ra, for example, 0.05 μm or less). On the other hand, in the final pass of the final cold rolling, rolling is performed using a roll having a large roughness (surface roughness Ra, for example, 0.06 μm or more), and the surface of the finally obtained copper foil may be roughened.

Here, in the final cold rolling, if the gloss G60 _RD of the surface measured in the parallel direction of the rolling in the first pass before the final pass exceeds 300, the final pass of the final cold rolling is in the last pass. Since the surface of the copper foil becomes relatively smooth, the shear deformation band becomes difficult to be introduced, which is preferable.

(3)d/t

When the thickness t of the copper foil is reduced, even if the same surface roughness is used, the ratio of the surface unevenness in the thickness of the copper foil becomes large, so that the evaluation of the surface of the copper foil of the above-mentioned G60 _RD /G60 _TD cannot be sufficiently performed. situation. Therefore, in the present invention, the evaluation of the surface of the copper foil can be carried out by specifying d/t ≦ 0.1 without depending on the thickness of the copper foil.

Here, d is as shown in FIG. 2, and the length of the copper foil in the rolling parallel direction RD is 175 μm, and the straight line direction TD is separated by three lines L ₁ to L ₃ of 50 μm or more, which corresponds to the maximum of the oil pit. The average of the difference di between the maximum height H _M and the minimum height Hs in the thickness direction of each of the straight lines L ₁ to L ₃ of the depth. Specifically, the distribution in the thickness direction on L ₁ to L ₃ is measured by the contact roughness, and the maximum height H _M and the minimum height Hs are obtained, and the di of the straight lines L ₁ to L ₃ may be averaged.

The thickness of the copper foil (or copper alloy foil) is not particularly limited, and for example, 5 to 50 μm can be preferably used.

(4) I/I ₀

In order to impart high flexibility to the copper foil of the present invention, the 200-ray diffraction intensity (I) obtained by X-ray diffraction of the rolling surface is determined to be relative in a state where the copper foil is heated to 200 ° C for 30 minutes to be recrystallized. The diffraction intensity (I ₀ ) of 200 obtained by X-ray diffraction of fine powder copper is 20 ≦ I / I ₀ ≦ 40. Thereby, the degree of orientation of the (200) plane is an appropriate value, and a copper foil excellent in balance between flexibility and etching property can be obtained. In this case, since the recrystallized texture having the crystal orientation of the (200) plane does not excessively expand, the tissue in the orientation other than the (200) plane is dispersed to some extent, and the disc is partially etched by the tissue. The type of subsidence also becomes smaller. Moreover, in order to impart higher flexibility to the copper foil of the present invention, it is preferably 25 ≦I/I ₀ ≦40 in a state where it is heated to 200 ° C for 30 minutes to be a recrystallized structure.

When I/I ₀ <20, the degree of orientation of the (200) plane is reduced, and the flexibility is lowered. When 40<I/I ₀ , the structure having a crystal orientation of the (200) plane increases, and the bendability is good, but the recrystallization texture of the (200) plane is excessively expanded, and as a result, the (200) plane is caused. The organization of the orientation is generated in a concentrated manner, and the tissue is etched more intensely, so that dishing is easily generated, and etching property is deteriorated. Further, the etching rate is greatly deteriorated because the etching speed is largely different between the (200) plane and the plane other than the surface.

The above annealing at 200 ° C for 30 minutes mimics the temperature history of the copper foil imparted in the CCL manufacturing step.

In addition, when the copper foil contains one or two or more selected from the group consisting of Ag, Sn, In, Au, Pd, and Mg in a total amount of 30 to 300 wtppm, it is easy to manage as 20≦I/I ₀ ≦ 40 is therefore more ideal.

As a method of managing 20 ≦I/I ₀ ≦40, for example, cold rolling and annealing may be repeated, and the average crystal grain size may be 10 to 20 μm in the final annealing, and then the thickness of the product may be delayed. The total workability is set to 90 to 96%, and the pass of the passband is inhibited before the final pass of the final cold rolling. In this case, calendering can be carried out using a roll having a relatively small roughness (surface roughness Ra is, for example, 0.05 μm or less) in the pass before the final pass of the final cold rolling.

(5) Azimuth difference of EBSD

As described above, the dish-type sinking system is used in the case where the copper foil is bonded to the resin film for heat treatment, and the crystal grains having different crystal orientations in the recrystallized uniform structure are present in a relatively large proportion. In the case, the individual crystal grains are etched deeper than the surroundings when etching is performed. Therefore, as the heat treatment, the copper foil is heated to a recrystallized structure by heat treatment conditions (at 200 ° C for 30 minutes) simulating the temperature history of the copper foil in the CCL production step. Further, in the crystal orientation of the state, when the surface of the copper foil is observed by EBSD after electrolytic polishing, it is preferable that the grain area ratio of the crystal orientation of the rolling surface to the [100] orientation is 15 degrees or more, and the area ratio of the crystal grains is 30 to 70. %.

When the area ratio is 30 to 70% when observed by EBSD, a copper foil excellent in both bendability and etching property can be obtained. When the area ratio is less than 30%, the etching property may be deteriorated, and if it exceeds 70%, the bendability may be lowered. Further, in the case of observation by EBSD, in order to make the area ratio 30 to 70%, it is preferable to carry out calendering using the following rolls in the final cold rolling as described above, in the final pass. In the previous pass, the expansion of the shear band was inhibited, that is, at the end of the final cold rolling A roller having a relatively small roughness (surface roughness Ra, for example, 0.05 μm or less) in the previous pass. In addition, when the copper foil contains one or two or more selected from the group consisting of Ag, Sn, In, Au, Pd, and Mg in a total amount of 30 to 300 wtppm, it is easy to manage the area ratio as 30 to 70%. Therefore, it is ideal.

Further, the copper foil which has been subjected to the thermal history and becomes CCL may be heated at 200 ° C for 30 minutes. The structure of the copper foil which has been subjected to heat treatment until recrystallization is hardly changed even if it is further heated. Therefore, in the observation of EBSD, the copper foil which receives the heat history and the copper foil which does not receive the heat history are not distinguished. Heat at 200 ° C for 30 minutes.

(6) Composition

As the copper foil, a tough pitch copper having a purity of 99.9 wt% or more, oxygen-free copper, and electric copper can be used. Further, it is preferable to contain a total of 30 to 300 wtppm selected from Ag, Sn, In, Au, Pd, and Mg. One or two or more of the group. The oxygen-free copper system specifications are JIS-H3510 (alloy No. C1011) and JIS-H3100 (alloy No. C1020), and the fine copper-based specifications are JIS-H3100 (alloy No. C1100).

Next, an example of a method for producing a rolled copper foil of the present invention will be described. First, the ingot consisting of copper and necessary alloying elements or even unavoidable impurities is hot rolled, then subjected to cold rolling and annealing, and finally to a specific thickness by final cold rolling.

Here, as described above, the surface of the copper foil is not roughened by the final pass of the final cold rolling, and the surface of the copper foil is roughened in the final pass of the final cold rolling. The surface of the final copper foil is roughened, and the shear deformation zone is reduced, the bendability is improved, and the dish form is reduced. Moreover, the surface with such a small shear deformation band becomes G60 _RD /G60 _TD <0.8.

Therefore, before the final pass of the final cold rolling, the surface of the copper foil is not roughened, and the roll having a relatively small roughness (surface roughness Ra, for example, 0.05 μm or less) is used for calendering, or the final The degree of processing in one pass of the cold rolling becomes large and the rolling can be performed. On the other hand, in the final pass of the final cold rolling, a roll having a relatively large roughness (surface roughness Ra, for example, 0.06 μm or more) is used, or a rolling oil having a high viscosity is used for rolling, and the final result is obtained. The surface of the copper foil becomes rough.

Furthermore, in order to roughen the surface of the final copper foil and to reduce the shear deformation zone, it is necessary to use the above-mentioned rougher roller in the final 2 passes of the final cold rolling, or in the final pass, or The calendering oil having a higher viscosity is used for calendering, but in terms of ease of adjustment, it is preferred to adjust the calendering conditions in the final pass. On the other hand, if the roughness of the roll is roughed before the final 3 passes of the final cold rolling, the shear deformation band expands.

Further, the annealing conditions may be adjusted so that the average particle diameter of the recrystallized grains obtained by the annealing before the final cold rolling is 10 to 20 μm. Further, the degree of rolling work in the final cold rolling may be 92 to 99%.

[Examples]

The elements described in Table 1 were added to the electrical copper, and cast in the atmosphere (Examples 1-3, 5) and the reducing environment (mixed gas of N ₂ and CO) (Examples 4, 6, 7 to 14). ingot. Further, Comparative Examples 1 to 5 were cast ingots in an argon atmosphere. Casting in the atmosphere contains oxygen of 150 to 300 ppm, and is cast in a reducing environment containing oxygen of the same degree as oxygen-free copper (C1020). The produced ingot is hot rolled at 800 ° C or higher until the thickness reaches 10 mm, and the surface scale is subjected to planar cutting, and after repeated cold rolling and annealing, it is formed to be 0.24 mm (Examples 1 to 12). After the thicknesses of 0.12 mm (Example 13), 0.36 mm (Example 14), and 1.2 mm (Comparative Examples 1 to 5) were annealed, the average crystal grain size was 13 μm. Further, it was finished into a final thickness of 0.012 mm (Examples 1 to 12, Comparative Examples 1 to 5), 0.006 mm (Example 13), and 0.018 mm (Example 14) in the final cold rolling. Further, the degree of processing of the final cold rolling of Examples 1 to 14 was 95%, and the degree of processing of the final cold rolling of Comparative Examples 1 to 5 was 99%.

Further, the final cold rolling was carried out in 5 to 15 passes, and as shown in Table 1, the surface roughness of the roll before the final pass and the surface roughness of the roll of the final pass were changed to be calendered. The surface roughness of the rolls from the first pass of the final calendering until the final pass is the same.

Each of the copper foil samples obtained in this manner was evaluated for each characteristic.

(1) Glossiness

The glosses G60 _RD and G60 _TD of the copper foil surface were measured in accordance with JIS-Z8741 along the rolling parallel direction RD and the rolling orthogonal direction TD, respectively.

(2) Cube collection organization

After heating the sample at 200 ° C for 30 minutes, an integral value (I) of the diffraction intensity of 200 obtained by X-ray diffraction of the rolled surface was obtained. The value is divided by the X-ray diffraction of the micro-powder copper (325 mesh, which is used after heating at 300 ° C for 1 hour in a hydrogen stream) to obtain an integral value (I ₀ ) of the diffraction intensity of 200. Calculate the I/I ₀ value.

(3) Maximum depth of the oil pit (average d)

Using a contact-type roughness meter (SE-3400 manufactured by Kosei Research Institute), as shown in Fig. 2, the length of the copper foil surface in the rolling parallel direction RD was 175 μm, and the circumferential direction of the rolling was determined to be 50 μm or more. The difference di between the maximum height H _M and the minimum height H _S of the three straight lines L ₁ to L ₃ . The di of each of the straight lines L ₁ to L ₃ is averaged as d. Furthermore, it is set to d (mm) / t (mm).

(4) Azimuth difference of EBSD

The surface of the sample after heating at 200 ° C for 30 minutes in (2) was subjected to electrolytic polishing using EBSD (Electronic Backscatter Diffraction Device, JEOL 8500F, Acceleration Voltage 20kV, Current 2e-8A, Measurement Range 1000 μm × 1000 μm, step width 5 μm) was observed. The area ratio of the crystal grains having an angular difference of 15 degrees or more from the [100] orientation was obtained by image analysis. Further, the number of crystal grains having a crystal grain size exceeding 20 μm in the observation range of 1 mm square on the surface of the sample was visually measured.

(5) Etchability

The etching property was evaluated in the following manner. First, the surface of the sample was etched at room temperature for 2 minutes using an etchant (ADEKATEC CL-8 (manufactured by Adeka Co., Ltd.) and DP-200 (manufactured by Ebara Ujilite)), and the image was observed by an optical microscope. The brightness of the image obtained by the surface of the observation range of 1 mm square is binarized, thereby calculating the ratio of light and dark. The tissue with [100] orientation will be brighter due to being parallel to the surface of the copper foil, and will be finer in other directions due to the surface. The bumps cause chaotic reflections and are observed to be darker.

Then, the proportion of the above-mentioned bright and dark parts is less than 50%, and is regarded as an organization with a smaller area ratio. Since the tissue having a smaller area ratio is surrounded by the tissue having a larger area ratio, the tissue having a smaller area ratio is approximated to a polygonal shape, and the portion having the smallest diameter of the circumscribed circle of the polygonal shape exceeding 50 μm is calculated. Number. Regardless of whether any liquid of ADEKATEC CL-8 or DP-200 is used, the part is less than 10 in the observation range, and the amount of etching before heating is heated at 200 ° C for 30 minutes after the final cold rolling, and finally cooled. The difference between the etching amount after heating at 200 ° C for 30 minutes after rolling is within ±10% is good (○), and the difference between the number of the above-mentioned numbers and the amount of etching is more than ±10. % is set as poor etching property (×).

Here, the etching amount is calculated by (the weight of the copper foil before etching - the weight of the copper foil after etching), and if the difference in the etching amount is within ±10%, the amount of etching is difficult regardless of whether or not recrystallization is performed after the final cold rolling. The change was confirmed to be excellent in etching property.

In addition, in the surface of the copper foil, the bright surface and the dark surface are mixed, and the bright surface or the dark surface tends to have a good etching property.

(6) Surface scars

The surface of each sample was visually observed, and the case where the flaw having a length of 10 mm or more in the rolling direction was present at 5 parts/m ² or more was set as ×.

(7) Flexibility

The sample was heated at 200 ° C for 30 minutes to recrystallize it. One side of the amine film (trade name: Kapton (registered trademark) EN) (surface joined to copper foil) was coated with a thermoplastic PI adhesive at 2 μm, and then dried to form a 27 μm thick resin layer. The adhesive layer area of the resin layer was layered on a copper foil, and vacuum thermocompression bonding was performed to prepare a copper clad laminate. The bending fatigue life of the copper clad laminate was measured by the bending test apparatus shown in Fig. 3 . This device is a structure in which the vibration transmitting member 3 is coupled to the oscillation transmitting member 3, and the test copper foil 1 is fixed to the device by a total of four portions of the screw 2 and the front end portion of the third portion indicated by the arrow. When the vibrating portion 3 is driven up and down, the intermediate portion of the copper foil 1 is bent at a specific radius of curvature r into a tubular shape. This test is to determine the number of times from the time of repeated bending to the time of breaking under the following conditions.

Further, the test conditions were as follows: test piece width: 12.7 mm, test piece length: 200 mm, test piece taking direction: taken in such a manner that the longitudinal direction of the test piece became parallel to the rolling direction, and the radius of curvature r: 2.5 mm, Vibration stroke: 25 mm, vibration speed: 1500 times / minute. In addition, when the bending fatigue life was 500,000 times or more, it was judged to have excellent flexibility. When the bending fatigue life is 500,000 times or more, the bending property of the foldable movable portion of the foldable mobile phone or the like is excellent.

The results obtained are shown in Table 1.

As is clear from Table 1, when G60 _RD is 100 or more and 300 or less, 20≦I/I ₀ ≦40, and d/t is 0.1 or less, and G60 _RD /G60 _{TD is} less than 0.8, the etching property is excellent. Further, the surface of the copper foil is free from scratches and the bending property is also good.

On the other hand, in the case of the final cold rolling, the surface roughness of the roll before the final pass, and the surface roughness of the roll of the final pass are both Ra = 0.05 μm or less, the surface of the copper foil The G60 _RD exceeds 300, and the surface of the copper foil is scratched, and the operability is deteriorated.

In the final cold rolling, the surface roughness of the roll before the final pass was increased to Ra = 0.06 μm or more, and the surface roughness of the roll of the final pass was Ra = 0.05 μm or less. In the case of I/I ₀ >40, the number of dishings is increased, the etching property is lowered, and the G60 _{RD of the} surface of the copper foil exceeds 300, and the surface of the copper foil is scratched, and the workability is deteriorated.

In the final cold rolling, in the case of Comparative Examples 3, 4, and 5 in which the surface roughness of the roll before the final pass and the surface roughness of the final pass roll were both coarsened to Ra=0.06 μm or more, When I/I ₀ >40, the number of dish sag increases, and the etchability decreases.

Further, in the case of Comparative Examples 3 and 4, since the surface roughness of all the rolls of the final cold rolling was made coarse, the shear deformation band spread inside the material, and the degree of orientation of the crystal on the surface of the copper foil was lowered. Become I/I ₀ >40.

On the other hand, in the case of Comparative Example 5, since the roughness of the roll up to the final pass was smoother than Comparative Examples 3 and 4, the gloss was also higher than the values of Comparative Examples 3 and 4, but shearing The suppression of the tape is still insufficient, and I/I ₀ >40, the number of dish-type sags increases, and the etching property decreases. In addition, in the state in which the roll roughness before the final pass is 0.07 μm, in order to suppress the shear band, there is a method of lowering the speed of the plate, and the like, in this case, the gloss exceeds 300. Therefore, the surface flaw is judged as ×.

1‧‧‧ copper foil

2‧‧‧ screws

3‧‧‧Vibration transfer member

4‧‧‧Oscillation driver

RD‧‧‧Rolling parallel direction

TD‧‧‧Rolling right angle

G _RD , G _TD , G60 _RD , G60 _TD ‧ ‧ gloss

L ₁ ~L ₃ ‧‧‧ Straight line

H _M ‧‧‧Maximum height

H _S ‧‧‧minimum height

Di‧‧‧The difference between the maximum height and the minimum height

R‧‧‧ radius of curvature

Figure 1 is a graph showing the relationship between oil pits and gloss.

Fig. 2 is a view showing a measurement method corresponding to the average value d of the maximum depth of the oil pit.

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

RD‧‧‧Rolling parallel direction

TD‧‧‧Rolling right angle

G _TD ‧‧‧Gloss

G _RD ‧‧‧Gloss

Claims (5)

A rolled copper foil obtained by calendering in a direction parallel to the direction of rolling in which the 60-degree gloss G60 _RD according to JIS-Z8741 is 100 or more and 300 or less, and is heated at 200 ° C for 30 minutes to be recrystallized into a recrystallized structure. The diffraction intensity of the 200-ray diffraction obtained by the X-ray diffraction of the surface (I) is 200 绕I/I ₀ ≦40 with respect to the diffraction intensity (I ₀ ) obtained by the X-ray diffraction of the fine powder copper. The length of the foil surface in the parallel direction of the rolling is 175 μm, and on the three straight lines separated by 50 μm or more in the direction perpendicular to the rolling direction, the average value d of the difference between the maximum height and the minimum height in the thickness direction of each straight line corresponding to the maximum depth of the oil pit is The ratio t/t of the thickness t of the copper foil is 0.1 or less, and the 60 degree gloss G60 _RD of the surface measured in the parallel direction of the rolling and the 60 degree gloss G60 according to JIS-Z8741 of the surface measured in the direction perpendicular to the rolling direction. The ratio of _{TD to} G60 _RD /G60 _{TD is} less than 0.8. The rolled copper foil according to claim 1, wherein the surface of the copper foil after heat treatment at 200 ° C for 30 minutes is observed by EBSD after electrolytic polishing, and the difference between the crystal orientation of the calendering surface and the [100] orientation is The area ratio of crystal grains of 15 degrees or more is 30 to 70%. The rolled copper foil according to claim 1 or 2, wherein the ingot is subjected to hot rolling, followed by cold rolling and annealing, and finally to final cold rolling, in the final cold rolling step, in the final In the first pass of the pass, the 60-degree gloss G60 _RD of the surface measured in the direction parallel to the calendering exceeds 300. For example, the rolled copper foil of claim 1 or 2 contains the total 30 to 300 wtppm of one or more elements selected from the group consisting of Ag, Sn, In, Au, Pd, and Mg. The rolled copper foil according to the third aspect of the invention, which contains a total of 30 to 300 wtppm of one or more elements selected from the group consisting of Ag, Sn, In, Au, Pd, and Mg.