KR20180100939A - Copper foil with minimized wringkle, electrode comprisng the same, secondary battery comprising the same and method for manufacturing the same - Google Patents

Abstract

One embodiment of the present invention provides a copper foil, which includes a copper layer and a rust preventive film disposed on a copper layer, and has a ratio of R_max to thickness (RRT) of 0.11 to 0.83, and a ratio of R_max to thickness deviation (RRTD) of 0.75 or less, wherein the RRT is obtained by following equation 1: RRT = R_max/T_copper, and the RRTD is obtained by following equation 2: RRTD=(RRT_max-RRT_min)/RRT_ave. One embodiment of the present invention seeks to provide the copper foil with minimized wrinkles or tears.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper foil having a reduced wrinkle and tear, an electrode including the same, a secondary battery including the same, and a method of manufacturing the same. BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to a copper foil with minimized wrinkles and tear, an electrode comprising the same, a secondary battery comprising the same, and a method of manufacturing the same.

The copper foil is used to manufacture various products such as a negative electrode of a secondary battery and a flexible printed circuit board (FPCB).

Of these, the copper foil produced by electroplating is also referred to as an electrolytic copper foil. Such an electrolytic copper foil is generally manufactured through a roll-to-roll (RTR) process, and is also used for manufacturing a negative electrode of a secondary battery, a flexible printed circuit board (FPCB), or the like through a roll-to-roll (RTR) process. Because continuous production is possible, the roll-to-roll (RTR) process is known as a process suitable for mass production of products. However, when the electrolytic copper foil is folded, torn, or wrinkled in the electrolytic copper foil during the roll-to-roll (RTR) process, the roll-to-roll process should be stopped and the problems must be resolved before the equipment is restarted. .

Especially, when the copper foil is wrinkled or torn in the step of manufacturing the secondary battery by using the copper foil, it becomes difficult to produce the stable product. As described above, wrinkling or tearing of the copper foil generated in the secondary battery manufacturing process lowers the production yield of the secondary battery and increases the manufacturing cost of the product.

A method of controlling the weight deviation of the copper foil to a low level is known as a method for solving the cause caused by the copper foil among the causes of wrinkles and tear defects generated in the secondary battery manufacturing process. However, control of the weight deviation of the copper foil has a limitation in solving the problems of wrinkles and tearing that occur in the secondary battery manufacturing process. Particularly, in recent years, in order to increase the capacity of the secondary battery, an ultra-thin copper foil, for example, a copper foil having a thickness of 8 mu m or less is used as an anode current collector. In this case, even if the weight deviation of the copper foil is precisely controlled, wrinkles and tearing failures occur intermittently in the manufacturing process of the secondary battery. Therefore, it is necessary to prevent or suppress the occurrence of wrinkles or tears in the manufacturing process of the secondary battery.

SUMMARY OF THE INVENTION The present invention is directed to a copper foil capable of solving the above problems, an electrode including the same, a secondary battery including the same, and a method of manufacturing the same.

One embodiment of the present invention seeks to provide a copper foil with minimized wrinkles or tears. An embodiment of the present invention is to provide a copper foil which is excellent in processability in roll-to-roll (RTR) by preventing occurrence of wrinkles and tearing in the manufacturing process of the secondary battery, even though it has a small thickness.

Another embodiment of the present invention is to provide an electrode for a secondary battery including such a copper foil and a secondary battery including such an electrode for a secondary battery.

Another embodiment of the present invention is to provide a flexible copper-clad laminate film comprising such a copper foil.

Another embodiment of the present invention is to provide a method of manufacturing a copper foil that can prevent the occurrence of wrinkles or tears during the manufacturing process.

Other features and advantages of the invention will be set forth in the description which follows, or may be learned by those skilled in the art from the description.

In order to solve this problem, an embodiment of the present invention provides a copper foil comprising a copper layer and a rust preventive film disposed on the copper layer and having a Ratio of Rmax to Thickness (RRT) of 0.11 to 0.83 and a Ratio of Ratio Rmax to Thickness Deviation). Here, the RRT is obtained by the following equation (1), and the RRTD is obtained by the following equation (2).

[Formula 1]

RRT = Rmax / T _copper

In Equation 1, Rmax is the maximum height roughness, and T _copper is the thickness of the _copper foil.

[Formula 2]

RRTD = (RRTmax - RRTmin) / RRTave

In Equation 2, RRTmax is the maximum value of the RRT, RRTmin is the minimum value of the RRT, and RRTave is the average value of the RRT.

In the copper foil, the FWHM variation ratio of the (220) plane after the heat treatment at 110 ° C for 30 minutes compared with that before the heat treatment is 0.81 to 1.19. Here, the half-value-width fluctuation rate is obtained by the following equation (3).

[Formula 3]

(Half-width after heat treatment) / (half-width before heat treatment)

The copper foil has a (220) plane, and the aggregate texture coefficient [TC (220)] of the (220) plane is 0.49 to 1.28.

The copper foil has a maximum profile height (Rp) of 0.36 to 1.17 mu m.

The copper foil has a weight deviation of 3% or less.

The rust preventive film includes at least one of chromium (Cr), a silane compound and a nitrogen compound.

The copper foil has a thickness of 4 mu m to 30 mu m.

Another embodiment of the present invention provides an electrode for a secondary battery comprising the copper foil and the active material layer disposed on the copper foil.

According to another embodiment of the present invention, there is provided a lithium ion secondary battery comprising a cathode, an anode disposed opposite to the anode, an electrolyte disposed between the anode and the cathode to provide an environment in which lithium ions can move, And a separator for electrically insulating the positive electrode and the negative electrode, wherein the negative electrode comprises the copper foil and the active material layer disposed on the copper foil.

Another embodiment of the present invention provides a flexible copper clad laminated film comprising a polymer film and the copper foil disposed on the polymer film.

Another embodiment of the present invention includes a step of passing a positive electrode plate and a rotating cathode drum spaced apart from each other in an electrolytic solution containing copper ions at a current density of 40 to 80 A / dm ² to form a copper layer , The electrolytic solution contains 70 to 90 g / L of copper ion, 50 to 150 g / L of sulfuric acid, 50 mg / L of silver (Ag) and 2 to 20 mg / L of allylthiourea (ATU) The present invention also provides a method of manufacturing a copper foil.

The electrolytic solution contains 2 to 20 mg / L of bis (3-sulfopropyl) disulfide (SPS).

The method of manufacturing a copper foil includes polishing a surface of the rotary cathode drum with a brush having a grain size of # 800 to # 3000 before forming the copper layer.

The method of manufacturing a copper foil further includes buffing the rotary cathode drum while spraying water in a width direction of the rotary cathode drum.

The electrolytic solution has a flow rate of 39 to 46 m ³ / hour.

The electrolytic solution has a flow velocity difference of 5% or less per unit time (second or second).

The foregoing general description of the present invention is intended to be illustrative of or explaining the present invention, but does not limit the scope of the present invention.

The copper foil according to one embodiment of the present invention has excellent resistance to creasing or tearing. Therefore, according to one embodiment of the present invention, occurrence of wrinkles or tears in the manufacturing process of the copper foil or the manufacturing process of the secondary battery using the copper foil is prevented. Thus, the copper foil according to one embodiment of the present invention has excellent roll-to-roll (RTR) processability.

According to another embodiment of the present invention, an electrode for a secondary battery in which occurrence of wrinkles or tears is prevented or minimized can be manufactured.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
1 is a schematic cross-sectional view of a copper foil according to an embodiment of the present invention.
2 is an example of an XRD graph of a copper foil.
3 is a schematic cross-sectional view of a copper foil according to another embodiment of the present invention.
4 is a schematic cross-sectional view of an electrode for a secondary battery according to another embodiment of the present invention.
5 is a schematic cross-sectional view of an electrode for a secondary battery according to another embodiment of the present invention.
6 is a schematic cross-sectional view of a secondary battery according to another embodiment of the present invention.
7 is a cross-sectional view of a flexible copper clad laminated film according to another embodiment of the present invention.
8 is a schematic view of the manufacturing process of the copper foil shown in Fig.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Accordingly, the invention includes all modifications and variations within the scope of the invention as defined in the appended claims and equivalents thereof.

The shapes, sizes, ratios, angles, numbers, and the like disclosed in the drawings are illustrative to describe embodiments of the present invention, and thus the present invention is not limited by what is shown in the drawings. Like elements throughout the specification may be referred to by like reference numerals.

Where the terms "comprises", "having", "comprising", and the like are used herein, other portions may be added unless the expression "only" is used. Where an element is referred to in the singular, it includes the plural unless specifically stated otherwise. Further, in interpreting the constituent elements, even if there is no separate description, it is interpreted to include an error range.

In the case of a description of the positional relationship, for example, if the positional relationship between two parts is described as 'on', 'on top', 'under', and 'next to' Or " direct " is used, one or more other portions may be located between the two portions.

In the case of a description of a temporal relationship, for example, if the temporal relationship is described by 'after', 'after', 'after', 'before', etc., May not be continuous unless they are not used.

In order to describe various components, expressions such as 'first', 'second', etc. are used, but these components are not limited by these terms. These terms are used only to distinguish one component from another. Therefore, the first component mentioned below may be the second component within the technical spirit of the present invention.

It should be understood that the term " at least one " includes all possible combinations from one or more related items.

It is to be understood that each of the features of the various embodiments of the present invention may be combined or combined with each other, partially or wholly, technically various interlocking and driving, and that the embodiments may be practiced independently of each other, It is possible.

1 is a schematic cross-sectional view of a copper foil 100 according to an embodiment of the present invention.

Referring to FIG. 1, a copper foil 100 includes a copper layer 110 and a rust preventive film 210 disposed on the copper layer 110.

According to one embodiment of the present invention, the copper layer 110 has a matte surface MS and a shiny surface SS on the opposite side thereof.

The copper layer 110 may be formed on the rotating cathode drum, for example, through electroplating (see FIG. 8). In this case, the shiny surface SS refers to the surface that has contacted the rotating cathode drum in the electroplating process, and the mat surface MS refers to the opposite surface to the shiny surface SS.

Although it is common that the shiny surface SS has a lower surface roughness Rz than the mat surface MS, an embodiment of the present invention is not limited thereto. The surface roughness Rz of the shiny surface SS may be equal to or higher than the surface roughness Rz of the mat surface MS.

The rust preventive film 210 may be disposed on at least one of the matte surface MS and the shiny surface SS of the copper layer 110. [ Referring to FIG. 1, a rust preventive film 210 is disposed on a mat surface MS. However, the embodiment of the present invention is not limited to this, and the rust preventive film 210 may be disposed only on the shiny surface SS or on both the mat surface MS and the shiny surface SS.

The rust preventive film 210 protects the copper layer 110. The anticorrosive film 210 can prevent the copper layer 110 from being oxidized or deteriorated during the preservation process. Therefore, the anticorrosive film 210 is also referred to as a protective layer.

According to one embodiment of the present invention, the anticorrosive film 210 may include at least one of chromium (Cr), a silane compound, and a nitrogen compound.

For example, the rust preventive film 210 can be made of a rust preventive solution containing chromium (Cr), that is, a rust preventive solution containing a chromic acid compound.

According to an embodiment of the present invention, the copper foil 100 has a first surface S1 as a surface in the direction of the mat surface MS and a second surface as a surface in the direction of the shiny surface SS, (S2). 1, the first surface S1 of the copper foil 100 is the surface of the anticorrosive film 210. As shown in FIG.

According to one embodiment of the present invention, the copper foil 100 has a Ratio of Rmax to Thickness (RRT) of 0.11 to 0.83. RRT means the ratio of the maximum height roughness (Rmax) to the thickness, and can be obtained by the following equation (1).

[Formula 1]

RRT = Rmax / T _copper

In Equation 1, T _copper is the thickness of the copper foil 100, and R max is the maximum height of the copper foil 100.

The thickness (T _copper ) of the _copper foil 100 is determined from the weight of the copper foil per unit area and the density of the copper foil.

For example, the thickness of the copper foil 100 can be obtained from a sample of the copper foil 100 having an area of 10 cm x 10 cm. That is, when the weight of the copper foil 100 having an area of 10 cm x 10 cm is Cg, the thickness of the copper foil 100 can be obtained by the following calculation formula, considering that the copper density is 8.94 g / cm ³ .

[formula]

The maximum height illumination (Rmax) can be measured with an illuminometer in accordance with JIS B 0601-2001. According to one embodiment of the present invention, the maximum height profile (Rmax) can be measured by the Mitutoyo SJ-310 model. Specifically, the measurement length excluding the cut-off length is 4 mm, and the cut-off length is 0.8 mm at the beginning and at the end, respectively. The radius of the stylus tip is 2 탆, and the measuring pressure is 0.75 mN. After setting as above, the Rmax value can be analyzed, which corresponds to the maximum height roughness (Rmax) based on the Mitutoyo roughness measurement value.

If the RRT of the copper foil 100 is less than 0.11, the maximum height roughness Rmax relative to the thickness T _copper is low and wrinkles due to slip may occur in the manufacture of secondary batteries using the copper foil 100 have. On the other hand, if the RRT exceeds 0.83, the maximum height roughness Rmax of the _copper foil 100 relative to the thickness T _copper is high, so that a notch is generated in the manufacture of a secondary battery or the like by a roll- So that tearing may occur in the copper foil 100.

Also, according to an embodiment of the present invention, the copper foil 100 has a Ratio of Rmax to Thickness Deviation (RRTD) of 0.75 or less. RRTD is the deviation of RRT. RRTD is obtained by the following equation (2).

[Formula 2]

RRTD = (RRTmax - RRTmin) / RRTave

In Equation 2, RRTmax is the maximum value of RRT, RRTmin is the minimum value of RRT, and RRTave is the average value of RRT. RRTmax, RRTmin, and RRTave can be obtained as follows. That is, RRT is measured and averaged three times at three points in the width direction of the copper foil 100, and the average value at the lowest point is referred to as RRTmin and the average value at the highest point is referred to as RRTmax. Also, the average of all the RRTs measured at three points is called RRTave.

If the RRTD exceeds 0.75, tearing may occur in the copper foil 100 in a manufacturing process of a secondary battery or the like using a roll-to-roll (RTR) process due to local RRT difference or RRT variation in the copper foil 100.

According to one embodiment of the present invention, the copper foil 100 has a maximum peak height Rp of 0.36 to 1.17 mu m. The maximum peak height (Rp) corresponds to the Maximum Profile Height according to JIS B 0601-2001.

If the maximum peak height Rp of the copper foil 100 is less than 0.36 mu m, the active sites that can uniformly coat the active materials on the surface of the copper foil 100 are not sufficiently provided, and the active material is coated unevenly. As a result, the capacity retention rate of the secondary battery is lowered.

If the maximum peak height Rp of the copper foil 100 exceeds 1.17 占 퐉, the acid on the surface of the copper foil 100 is too high to uniformly coat the active material, and the capacity retention rate of the secondary battery may be lowered.

According to an embodiment of the present invention, the variation ratio of the full width at half maximum (FWHM) of the (220) face of the copper foil 100 after the heat treatment at 110 ° C for 30 minutes before the heat treatment is 0.81 to 1.19.

The half-value width fluctuation rate is obtained by the following equation (3).

[Formula 3]

(FWHM) variation ratio = (full width after heat treatment) / (full width before heat treatment)

Here, the half-value width can be obtained from the XRD graph of the copper foil 100. [

Referring to FIG. 2, X-ray diffraction (XRD) [Target: Copper K alpha 1, (ii) 2θ interval: 0.01 °, (iii) 2θ scan speed: 3 DEG / min], an XRD graph having peaks corresponding to n crystal faces can be obtained. (FWHM) of the (220) plane of the copper foil 100 can be measured from the XRD graph of the copper foil 100 obtained.

The half-width before heat treatment is the half-width of the (220) plane of the copper foil 100 measured at room temperature (25 캜 15 캜) and the half-width of the copper foil 100 measured after heat treatment at 110 캜 for 30 minutes 220) plane.

The FWHM variation ratio of the XRD peak to the (220) plane of the copper foil 100 is less than 0.81 or more than 1.19 because of the thermal history of the secondary battery 100, Is significantly changed. Wrinkles may be generated in the secondary battery manufacturing process due to roll-to-roll (RTR) due to such dimensional fluctuation.

According to an embodiment of the present invention, the copper foil 100 has a (220) face, and the aggregate texture coefficient TC (220) of the (220) face of the copper foil 100 is 0.49 to 1.28. The texture factor [TC (220)] is related to the crystal structure of the surface of the copper foil 100.

Hereinafter, with reference to Fig. 2, a method of measuring and calculating the aggregate texture coefficient TC (220) of the (220) plane will be described according to an embodiment of the present invention.

2 is an example of an XRD graph of a copper foil.

First, by the X-ray diffraction (XRD) (Target: Copper K alpha 1, 2θ interval: 0.01 °, 2θ scan speed: 3 ° / min) in the range of 30 ° to 95 ° in the diffraction angle An XRD graph having peaks corresponding to the crystal planes is obtained. For example, an XRD graph may be obtained in which peaks corresponding to the (111) plane, the (200) plane, the (220) plane, and the (311) plane are illustrated as illustrated in FIG.

Next, the XRD diffraction intensity [I (hkl)] of each crystal face hkl is obtained from this graph. In addition, the XRD diffraction intensity [I ₀ (hkl)] for each of the n crystal planes of the standard copper powder specified by JCPDS (Joint Committee on Powder Diffraction Standards) is obtained. Then, if I (hkl) / I is the arithmetic mean value of ₀ (hkl) is calculated, and in that the arithmetic mean value (220) I (220) / I 0 (220) is 220 by being divided in the plane of the n crystal plane (TC (220)) is calculated. That is, the texture factor [TC (220)] of the (220) plane is calculated based on the following expression (4).

[Formula 4]

According to one embodiment of the present invention, the (220) face of each of the first and second faces S1 and S2 of the copper foil 100 may have a texture index TC (220) of 0.49 to 1.28.

The higher the aggregate texture coefficient TC (220) of the (220) plane, the more dense the crystalline structure of the copper foil 100 is.

If the aggregate texture coefficient TC (220) of the (220) plane is less than 0.49, the crystal structure of the copper foil 100 is not dense and the structure is deformed by the stress and heat received in the secondary battery manufacturing process, Wrinkles are generated. If the coefficient of texture of the (220) plane exceeds 1.28, the structure of the copper foil 100 becomes too dense and brittleness becomes strong, so that the copper foil 100 is torn during the manufacturing process of the secondary battery, making it difficult to produce a stable product.

According to one embodiment of the present invention, the copper foil 100 has a weight deviation of 3% or less.

According to one embodiment of the present invention, " weight deviation " is determined by taking samples of 5 cm x 5 cm at three points arranged along the width direction of the copper foil 100, i.e., TD (Transverse Direction) The weight can be obtained by calculating the weight per unit area and calculating the " average weight at three points " and " standard deviation of weight " from the weight per unit area of three samples. The weight deviation can be obtained by the following equation (5).

[Formula 5]

If the weight deviation of the copper foil 110 exceeds 3%, the copper foil 100 may be wrinkled or cried due to the tension or weight overlapping the copper foil 110 during the roll-to-roll process for manufacturing the secondary battery.

According to one embodiment of the present invention, the copper foil 100 may have a thickness of 4 탆 to 30 탆. When the thickness of the copper foil 100 is less than 4 mu m, the workability in the manufacturing process of the electrode or secondary battery using the copper foil 100 is lowered. When the thickness of the copper foil 100 is more than 30 mu m, the thickness of the electrode for the secondary battery using the copper foil 100 becomes large, and it may be difficult to realize a high capacity of the secondary battery due to such a large thickness.

3 is a schematic cross-sectional view of a copper foil 200 according to another embodiment of the present invention. Hereinafter, in order to avoid redundancy, a description of the components already described is omitted.

3, a copper foil 200 according to another embodiment of the present invention includes two copper foils 110 and two copper foils 110 disposed on a mat surface MS and a shiny surface SS, respectively, Films 210 and 220, respectively. Compared to the copper foil 100 shown in Fig. 1, the copper foil 200 shown in Fig. 3 further includes the anticorrosive film 220 disposed on the shiny side SS of the copper layer 110. Fig.

The rust preventive film 210 disposed on the mat surface MS of the copper layer 110 among the two rust preventive films 210 and 220 is referred to as a first protective layer and is disposed on the shiny surface SS The rust-preventive film 220 may be referred to as a second protective layer.

The first surface S2 of the copper foil 200 shown in Fig. 3 is the same as the surface of the anticorrosive film 210 disposed on the mat surface MS and the second surface S2 is the shiny surface SS. And the surface of the anticorrosive film 220 disposed on the antireflection film 220 is the same.

According to another embodiment of the present invention, the two rustproofing films 210 and 220 may include at least one of chromium (Cr), a silane compound, and a nitrogen compound, respectively.

The copper foil 200 shown in Fig. 3 has an RRT of 0.11 to 0.83 and an RRTD of 0.75 or less. Also, the FWHM variation ratio of the (220) plane of the copper foil 200 after the heat treatment at 110 ° C for 30 minutes before the heat treatment is 0.81 to 1.19.

In addition, the (220) face of the copper foil 200 has an aggregate texture coefficient TC (220) of 0.49 to 1.28.

The copper foil 200 shown in Fig. 3 has a maximum peak height Rp of 0.36-1.17 탆, a weight deviation of 3% or less, and a thickness of 4 탆 to 30 탆.

4 is a schematic cross-sectional view of an electrode 300 for a secondary battery according to another embodiment of the present invention.

The secondary battery electrode 300 shown in Fig. 4 can be applied to the secondary battery 500 shown in Fig. 6, for example.

Referring to FIG. 4, an electrode 300 for a secondary battery according to another embodiment of the present invention includes a copper foil 100 and an active material layer 310 disposed on the copper foil 100. Here, the copper foil 100 is used as a current collector.

The electrode 300 for a secondary battery according to another embodiment of the present invention includes a copper foil 100 having a first surface S1 and a second surface S2 and a first surface And an active material layer 310 disposed on at least one of the first surface S1 and the second surface S2.

FIG. 4 shows that the copper foil 100 of FIG. 1 is used as a current collector. However, another embodiment of the present invention is not limited thereto, and the copper foil 200 shown in FIG. 3 may be used as a collector of the electrode 300 for a secondary battery.

4 shows a structure in which the active material layer 310 is disposed on only the first surface S1 of the surfaces S1 and S2 of the copper foil 100. However, It is not. The active material layer 310 may be disposed on both the first surface S1 and the second surface S2 of the copper foil 100 and the active material layer 310 may be disposed on only the second surface S2 of the copper foil 100 .

The active material layer 310 shown in FIG. 4 is made of an electrode active material, and may be made of a negative electrode active material. That is, the secondary battery electrode 300 shown in FIG. 4 can be used as a negative electrode.

The active material layer 310 may include at least one of carbon, a metal, an oxide of a metal, and a complex of a metal and carbon. As the metal, at least one of Ge, Sn, Li, Zn, Mg, Cd, Ce, Ni and Fe may be used. In addition, in order to increase the charge / discharge capacity of the secondary battery, the active material layer 310 may include silicon (Si).

When the copper foil 100 according to an embodiment of the present invention is used, tearing or wrinkling of the copper foil 100 is prevented during the manufacturing process of the electrode 300 for a secondary battery. Accordingly, the manufacturing efficiency of the electrode 300 for the secondary battery is improved, and the charge / discharge efficiency and the capacity retention rate of the secondary battery including the secondary battery electrode 300 can be improved.

5 is a schematic cross-sectional view of an electrode 400 for a secondary battery according to another embodiment of the present invention.

An electrode 400 for a secondary battery according to another embodiment of the present invention includes a copper foil 200 and active material layers 310 and 320 disposed on the copper foil 200.

Referring to FIG. 5, the copper foil 200 includes a copper layer 110 and two rustproofing films 210 and 220 disposed on both sides of the copper layer 110.

The secondary battery electrode 300 shown in FIG. 5 includes two active material layers 310 and 320 disposed on both sides of the copper foil 200. The active material layer 310 disposed on the first surface S1 of the copper foil 200 is referred to as a first active material layer and the active material layer 320 disposed on the second surface S2 of the copper foil 200 is referred to as a first active material layer The second active material layer.

The two active material layers 310 and 320 may be made of the same material by the same method, or may be made of different materials or by other methods.

6 is a schematic cross-sectional view of a secondary battery 500 according to another embodiment of the present invention. The secondary battery 500 shown in Fig. 6 is, for example, a lithium secondary battery.

6, the secondary battery 500 includes a cathode 370, an anode 340 disposed opposite to the anode 370, and an anode 340 disposed between the anode 370 and the cathode 340, An electrolyte 350 that provides a movable environment and a separator 360 that electrically isolates the anode 370 from the cathode 340. Here, the ions moving between the anode 370 and the cathode 340 are lithium ions. The separator 360 separates the positive electrode 370 and the negative electrode 340 from each other in order to prevent the charge generated from one electrode from being transferred to the other electrode through the interior of the secondary battery 500 and wastefully consumed. Referring to FIG. 6, a separation membrane 360 is disposed within the electrolyte 350.

The anode 370 includes a cathode current collector 371 and a cathode active material layer 372. An aluminum foil may be used for the positive electrode current collector 371.

The cathode 340 includes a cathode current collector 342 and an active material layer 341. The active material layer 341 of the cathode 340 includes a negative electrode active material.

As the anode current collector 342, the copper foils 100 and 200 disclosed in Figs. 1 and 3 may be used. The secondary battery electrodes 300 and 400 shown in FIGS. 4 and 5 may be used as the cathode 340 of the secondary battery 500 shown in FIG.

7 is a schematic cross-sectional view of a flexible copper clad laminated film 600 according to another embodiment of the present invention.

The flexible copper-clad laminate film 600 according to another embodiment of the present invention includes a polymer membrane 410 and a copper foil 100 disposed on the polymer membrane 410. Although the flexible copper-clad laminated film 600 including the copper foil 100 shown in Fig. 1 is shown in Fig. 7, another embodiment of the present invention is not limited thereto. For example, the copper foil 200 shown in Fig. 3 or another copper foil may be used for the flexible copper-clad laminated film 600 according to another embodiment of the present invention.

The polymer membrane 410 has flexibility and nonconductivity. There is no particular limitation on the kind of the polymer membrane 410. The polymer film 410 may include, for example, polyimide. The polyimide film and the copper foil 100 are laminated through a roll press to form the flexible copper clad laminated film 600. [ Alternatively, the polyimide precursor solution may be coated on the copper foil 100 and then heat-treated to form the flexible copper-clad laminated film 600.

The copper foil 100 is formed of a copper foil 110 having a matte surface MS and a shiny surface SS and a rust preventive film (not shown) disposed on at least one of a matte surface MS and a shiny surface SS of the copper layer 110 210). Here, the anticorrosive film 210 may be omitted.

Referring to FIG. 7, the polymer membrane 410 is disposed on the rust preventive film 210, but the present invention is not limited thereto. The polymer membrane 410 may be disposed on the shiny surface SS of the copper layer 110. [

Hereinafter, a method of manufacturing the copper foil 200 according to another embodiment of the present invention will be described in detail with reference to FIG.

8 is a schematic view of a method of manufacturing the copper foil 200 shown in Fig.

First, a positive electrode plate 13 and a rotating negative electrode drum 12 spaced apart from each other in an electrolytic solution 11 containing copper ions are supplied with a current density of 40 to 80 ASD (A / dm ² ) to form a copper layer 110, .

The electrolytic solution 11 contains 70 to 90 g / L of copper ions and 50 to 150 g / L of sulfuric acid.

The electrolytic solution (11) contains silver (Ag) of 50 mg / L or less. Here, the silver (Ag) includes silver ions (Ag +) in an ionic state dissociated to the electrolytic solution (11).

In the electrolytic solution 11, silver (Ag) corresponds to an impurity, and the concentration of silver (Ag) is controlled to be 50 mg / L or less. When the concentration of silver (Ag) in the electrolytic solution 11 exceeds 50 mg / L, the maximum height illuminance Rmax of the copper foil 200 increases and the RRT exceeds 0.83.

A raw material that does not contain silver is used to adjust the silver concentration in the electrolyte solution 11 to 50 mg / L or less, or silver (Ag) in the plating solution is not introduced into the electrolyte solution 11 do. By supplying chlorine (Cl) to the electrolytic solution (11) so as to deposit silver (Ag) in the form of silver chloride (AgCl) so as to keep the silver (Ag) concentration in the electrolytic solution (11) (Ag) can be removed.

Further, the electrolyte solution 11 may contain an additive. As an additive, for example, Allylthiourea (ATU) may be used. The electrolyte solution 11 may contain 2 to 20 mg / L of allylthiourea (ATU).

Allylthio urea (ATU) is also referred to as N-Allylthiourea, and can be represented by the following formula (1).

[Chemical Formula 1]

According to an embodiment of the present invention, the half-width FWHM of the (220) face of the copper foil 100 can be controlled by the kind and concentration of the additive. Particularly, by adjusting the concentration of the allyl thiourea (ATU) The full width at half maximum (FWHM) of the (220) face of the copper foil 100 can be adjusted. When the concentration of the allylthio urea (ATU) is less than 2 mg / L or exceeds 20 mg / L, the fluctuation rate of the FWHM becomes less than 0.81 or exceeds 1.19.

As another additive, bis (3-sulfopropyl) disulfide (SPS) may be used. That is, the electrolyte solution 11 may contain 2 to 20 mg / L of bis (3-sulfopropyl) disulfide (SPS). Bis (3-sulfopropyl) disulfide (SPS) can be used as a polish agent.

When the concentration of bis (3-sulfopropyl) disulfide (SPS) in the electrolytic solution 11 exceeds 20 mg / L, the aggregate structure of the (220) plane of the copper foil 100 develops, Is greater than 1.28. Conversely, when the concentration of bis (3-sulfopropyl) disulfide (SPS) in the electrolytic solution 11 is less than 2 mg / L, the aggregate structure coefficient of the (220) face of the copper foil 100 becomes less than 0.49.

Concretely, the positive electrode plate 13 and the rotating negative electrode drum 12, which are arranged so as to be spaced apart from each other in the electrolytic solution 11 contained in the electrolytic bath 10, are energized at a current density of 40 to 80 ASD (A / dm ² ) 12 may be electrodeposited to form the copper layer 110. [ The distance between the positive electrode plate 13 and the rotating cathode drum 12 can be adjusted in the range of 8 to 13 mm.

The higher the current density applied between the positive electrode plate 13 and the rotating cathode drum 12, the more uniform plating is performed to reduce the surface roughness of the matte surface MS of the copper layer 110. As the current density becomes lower, So that the surface roughness of the mat surface MS of the copper layer 110 is increased.

The surface roughness of the shiny surface SS of the copper layer 110 may vary depending on the degree of polishing of the surface of the rotating cathode drum 12. [ The surface of the rotary cathode drum 12 can be polished with a brush having a grain size of, for example, # 800 to # 3000 before the formation of the copper layer 110, for the purpose of adjusting the surface roughness of the shiny surface SS. have. If the particle size (#) of the brush exceeds # 3000, the RRT may be less than 0.11.

In addition, when buffing the rotary cathode drum 12, water is sprayed in the width direction of the rotary cathode drum 12 so that uniform buffing can be performed in the width direction of the rotary cathode drum 12 .

In the process of forming the copper layer 110, the electrolyte solution 11 can be maintained at a temperature of 40 to 65 占 폚.

In order to reduce the content of impurities in the electrolytic solution 11, a copper wire serving as a material for copper ions is heat-treated, the heat-treated copper wire is pickled, and the pickled copper wire is then injected into the sulfuric acid for electrolytic solution.

The electrolytic solution 11 may have a flow rate of 39 to 46 m ³ / hour. That is, the electrolytic solution 11 can be circulated at a flow rate of 39 to 46 m ³ / hour in order to remove the solid impurities existing in the electrolytic solution 11 while electroplating is performed. The electrolytic solution 11 can be filtered during the circulation process of the electrolytic solution 11. [ By removing silver chloride (AgCl) by such filtration, the silver (Ag) content in the electrolytic solution 11 can be maintained at 50 mg / L or less.

If the flow rate of the electrolytic solution 11 is less than 39 m ³ / hour, the flow velocity may be low and an overvoltage may be generated and the copper layer 110 may be formed non-uniformly. On the other hand, if the flow rate exceeds 46 m ³ / hour, filter damage may be caused and foreign matter may flow into the electrolyte solution 11.

In order to make the copper foil 200 have a weight deviation of 3% or less in the width direction, a deviation (hereinafter referred to as " flow velocity deviation ") of the electrolytic solution 11 per unit time . When the flow rate deviation of the electrolyte solution 11 per unit time (sec) exceeds 5%, the nonuniform copper layer 110 can be formed by nonuniform plating, thereby increasing the weight deviation of the copper foil 200 can do.

In addition, when the flow rate deviation of the electrolyte solution 11 per unit time (second) exceeds 5%, the RRTD of the copper foil 200 may exceed 0.75 by nonuniform plating.

On the other hand, the degree of cleanliness of the electrolytic solution 11 can be maintained or improved by introducing hydrogen peroxide and air into the electrolytic solution 11 while the electrolytic solution 11 is ozone-treated or the copper layer 110 is formed by electroplating.

Next, the copper layer 110 is cleaned in the cleaning tank 20.

In order to remove impurities on the surface of the copper layer 110, washing may be performed in the cleaning tank 20. [ Alternatively, acid cleaning may be performed to remove impurities on the surface of the copper layer 110, and then water cleaning may be performed to remove the acidic solution used for pickling. The cleaning process may be omitted.

Next, the anticorrosive films 210 and 220 are formed on the copper layer 110.

8, the copper layer 110 may be immersed in the rust preventive liquid 31 contained in the anti-corrosion bath 30, and the anti-corrosive films 210 and 220 may be formed on the copper layer 110. Here, the rust preventive liquid 31 includes chromium, and the chromium (Cr) in the rust preventive liquid 31 may exist in an ionic state. The rust preventive liquid 31 may contain 0.5 to 5 g / L of chromium. The thus formed rust preventive films 210 and 220 are also referred to as a protective layer.

On the other hand, the anticorrosive films 210 and 220 may contain a silane compound by silane treatment or may contain a nitrogen compound by nitrogen treatment.

The copper foil 200 is formed by forming the antirust films 210 and 220.

Next, the copper foil 200 is cleaned in the cleaning tank 40. Such a cleaning process may be omitted.

Next, after the drying process is performed, the copper foil 200 is wound on the winder WR.

Hereinafter, the present invention will be described in detail with reference to production examples and comparative examples. However, the following preparations are only for the understanding of the present invention, and the scope of the present invention is not limited to these preparations.

Manufacturing example  1-7 and Comparative Example  1-7

A copper foil was manufactured by using a negative electrode plate including an electrolytic bath 10, a rotating negative electrode drum 12 disposed in the electrolytic bath 10, and a positive electrode plate 13 disposed apart from the rotating negative electrode drum 12. The electrolytic solution 11 was a copper sulfate solution. The electrolytic solution 11 had a copper ion concentration of 75 g / L, a sulfuric acid concentration of 100 g / L and a temperature of the electrolytic solution 11 of 55 ° C.

The rotating cathode drum 12 was polished by a brush having the particle size as described in Table 1. [

The electrolytic solution (11) contains 10 mg / L of polyethylene glycol as an additive. The electrolytic solution 11 contains silver (Ag), allyl thiourea (ATU) and bis (3-sulfopropyl) disulfide (SPS) The electrolyte 11 is circulated at a flow rate of 42 m ³ / hour, and the deviation of the flow rate per unit time (second) (flow velocity deviation) is as shown in Table 1.

A current density of 60 ASD was applied between the rotating drum 12 and the positive electrode plate 13 to form the copper layer 110. [

Next, the copper layer 110 was immersed in the rust preventive solution 31 contained in the anti-corrosion bath 30 to form the rust preventive films 210 and 220 containing chromium on the surface of the copper layer 110. [ At this time, the temperature of the rust preventive liquid 31 was maintained at 30 占 폚, and the rust preventive liquid 31 contained 2.2 g / L of chromium (Cr). As a result, the copper foils of Production Example 1-7 and Comparative Example 1-7 were produced.

division Brush size (#) Ag (mg / L) ATU (mg / L) SPS (mg / L) Velocity deviation (% / sec) Production Example 1 3000 25 11 11 3 Production Example 2 2000 48 11 11 2.8 Production Example 3 2000 25 3 11 2.8 Production Example 4 2000 25 19 11 2.8 Production Example 5 2000 25 11 11 4.8 Production Example 6 2000 25 11 3 2.8 Production Example 7 2000 25 11 19 2.8 Comparative Example 1 4000 25 11 11 0.18 Comparative Example 2 2000 52 11 11 0.18 Comparative Example 3 2000 25 One 11 0.18 Comparative Example 4 2000 25 22 11 0.18 Comparative Example 5 2000 25 11 11 5.3 Comparative Example 6 2000 25 11 One 0.18 Comparative Example 7 2000 25 11 22 0.18

(I) RRT, (ii) RRTD, (iii) FWHM fluctuation rate and (iv) the aggregate texture of the (220) plane for the copper foils of Production Example 1-7 and Comparative Example 1-7 thus produced. The coefficient [TC (220)] was measured. The results are shown in Table 2.

(i) RRT

The copper foils of Production Example 1-7 and Comparative Example 1-7 were cut to a size of 10 cm x 10 cm and weighed to determine the weight per unit area thereof. The density (8.94 g / cm ³ ) of copper was used to determine the thickness T _copper ).

In addition, according to JIS B 0601-2001 standard, the maximum height illuminance (Rmax) was measured using an illuminometer. Specifically, the maximum height roughness (Rmax) was measured by a Mitutoyo SJ-310 model. In this case, the measured length excluding the cut-off length was 4 mm, and the cut-off length was 0.8 mm at the beginning and at the end. The radius of the stylus tip was 2 탆, and the measurement pressure was 0.75 mN. As described above, the Rmax value was measured after the setting, and this corresponds to the maximum height illuminance (Rmax) based on the Mitutoyo illuminometer measurement value.

The RRT is obtained by the following equation (1).

[Formula 1]

RRT = Rmax / T _copper

(ii) RRTD (Ratio of Rmax  to Thickness Deviation)

RRT is measured and averaged three times at three points in the width direction of the copper foil. The average value of the lowest point is called RRTmin, and the average of the highest point is called RRTmax. The average of all RRTs measured at three points is called RRTave. Using RRTmax, RRTmin, and RRTave, RRTD was calculated according to the following equation (2).

[Formula 2]

RRTD = (RRTmax - RRTmin) / RRTave

(iii) Half full width Rate of change

An XRD graph of the copper foil was obtained at room temperature (25 ° C ± 15 ° C). Concretely, X-ray diffraction (XRD) (Target: Copper K alpha 1, (ii) 2θ interval: 0.01 °, (iii) 2θ scan speed at 30 ° to 95 ° diffraction angle 3 [deg.] / Min], an XRD graph having peaks corresponding to n crystal faces was obtained. The FWHM of the (220) face of the copper foil before the heat treatment was measured from the XRD graph of the obtained copper foil. Next, the copper foil was heat-treated at 110 DEG C for 30 minutes, and then an XRD graph of the copper foil was obtained. Then, the FWHM of the copper foil after the heat treatment of the (220) face was measured. The FWHM fluctuation rate is obtained by the following equation (3).

[Formula 3]

(FWHM) variation ratio = (full width after heat treatment) / (full width before heat treatment)

(iv) ( 220) face  Aggregate organization factor [ TC (220)]

(XRD) (Target: Copper K alpha 1, (ii) 2θ interval: 0.01 °, (iii) 2θ scan speed: 3 ° / ° in the range of 30 ° to 95 ° diffraction angle min] to obtain an XRD graph having peaks corresponding to n crystal planes, and XRD diffraction intensity [I (hkl)] of each crystal plane hkl was obtained from this graph. In addition, the XRD diffraction intensity [I ₀ (hkl)] of each of the n crystal planes of the standard copper powder specified by JCPDS (Joint Committee on Powder Diffraction Standards) was determined. Then, if the arithmetic mean value obtained after obtaining the arithmetic mean value of I (hkl) / I ₀ (hkl) of the n crystal plane (220) I (220) / I 0 (220) of the copper foil 220 by dividing the surface (TC) (220) was calculated. The texture factor [TC (220)] of the (220) plane was calculated based on the following equation (4).

[Formula 4]

(v) Observation of wrinkles and tears

1) Negative electrode manufacturing

2 parts by weight of styrene butadiene rubber (SBR) and 2 parts by weight of carboxymethyl cellulose (CMC) were mixed with 100 parts by weight of carbon for a commercially available negative electrode active material, and a slurry for an anode active material was prepared using distilled water as a solvent. A slurry for negative electrode active material was applied on the copper foil of Production Example 1-7 and Comparative Example 1-7 having a width of 10 cm using a doctor blade to a thickness of 40 탆 and dried at 120 캜 and a pressure of 1 ton / To prepare a negative electrode for a secondary battery.

2) Manufacture of electrolytic solution

A basic electrolytic solution was prepared by dissolving LiPF ₆ as a solute in a non-aqueous organic solvent in which ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed at a ratio of 1: 2 in a concentration of 1M. A non-aqueous electrolyte was prepared by mixing 99.5% by weight of the basic electrolyte and 0.5% by weight of succinic anhydride.

3) Anode manufacturing

Li _{1 . 1} Mn _{1 . 85} Al _{0 . 05} O ₄ and lithium manganese oxide having an orthorhombic crystal structure of o-LiMnO ₂ were mixed at a ratio of 90:10 (weight ratio) to prepare a cathode active material. The cathode active material, carbon black, and PVDF [poly (vinylidenefluoride)] as a binder were mixed at a weight ratio of 85: 10: 5 and mixed with NMP as an organic solvent to prepare a slurry. The slurry thus prepared was coated on both sides of a thick foil of 20 탆 thick and dried to prepare a positive electrode.

4) Manufacture of lithium secondary battery for test

A lithium secondary battery in the form of a coin was produced by disposing an anode and a cathode in the aluminum can to insulate the aluminum can from each other, and arranging a non-aqueous electrolyte and a separator therebetween. Polypropylene (Celgard 2325; thickness 25 μm, average poresize 28 nm, porosity 40%) was used as a separator.

5) Observation of wrinkles and tears

The tearing and wrinkling of the copper foil were observed during the production of a series of lithium secondary batteries. Especially, copper foil tearing and wrinkle occurrence were visually observed during negative electrode manufacturing process. A case in which wrinkles or tears did not occur was indicated as " good ".

The results of the above tests and observations are shown in Table 2 below.

RRT RRTD Half-width variation (220) plane texture coefficient wrinkle Tear Production Example 1 0.13 0.34 0.98 0.89 Good Good Production Example 2 0.82 0.34 0.98 0.88 Good Good Production Example 3 0.55 0.33 0.82 0.86 Good Good Production Example 4 0.56 0.34 1.17 0.87 Good Good Production Example 5 0.55 0.74 0.99 0.86 Good Good Production Example 6 0.55 0.36 1.01 0.51 Good Good Production Example 7 0.55 0.35 1.01 1.26 Good Good Comparative Example 1 0.09 0.33 0.98 0.86 Occur Good Comparative Example 2 0.85 0.33 0.98 0.87 Good Occur Comparative Example 3 0.56 0.34 0.79 0.86 Occur Good Comparative Example 4 0.55 0.35 1.22 0.87 Occur Good Comparative Example 5 0.56 0.77 1.01 0.87 Occur Good Comparative Example 6 0.55 0.36 0.99 0.47 Occur Good Comparative Example 7 0.55 0.35 0.99 1.30 Good Occur

The copper foil was wrinkled or torn during the production of the lithium secondary battery using the copper foil of Comparative Example 1-7. However, in the process of manufacturing the lithium secondary battery using the copper foil according to Production Example 1-7, No tearing occurred.

Concretely, wrinkles or tears occurred in the process of producing a lithium secondary battery using the following copper foil.

(1) Comparative Example 1 (wrinkle generation) in which the surface of the rotary cathode drum 12 was polished with a brush having a particle size exceeding # 3000 and the RRT was less than 0.11;

(2) Comparative Example 2 (tearing occurred) in which the negative (Ag) content in the electrolytic solution exceeds 50 mg / L and the RRT exceeds 0.83;

(3) Comparative Example 3 (wrinkle occurrence) in which the content of allyl thiourea (ATU) in the electrolytic solution is less than 2 mg / L and the half-width variation ratio is less than 0.81;

(4) Comparative Example 4 (wrinkle occurrence) in which the content of allyl thiourea (ATU) in the electrolytic solution exceeds 20 mg / L and the half-width variation ratio exceeds 1.19;

(5) Comparative Example 5 (wrinkle occurrence) in which the flow rate difference of the electrolytic solution exceeds 5% per second and the RRTD exceeds 0.75;

(6) Comparative Example 6 (wrinkle generation) in which the content of bis (3-sulfopropyl) disulfide (SPS) is less than 2 mg / L and the texture coefficient of the (220) plane [TC (220)] is less than 0.49;

(7) Comparative Example 7 (occurrence of tearing) in which the content of bis (3-sulfopropyl) disulfide (SPS) exceeds 20 mg / L and the texture coefficient [TC (220) .

The copper foil according to Comparative Example 1-7 can be evaluated as unsuitable as an anode current collector for a lithium secondary battery.

On the other hand, the copper foils of Production Examples 1 to 7 produced in the condition range according to the embodiments of the present invention are not torn in the process of manufacturing the lithium secondary battery, and wrinkles are not generated in the copper foil. Therefore, the copper foil according to the embodiments of the present invention has excellent roll-to-roll (RTR) processability and can be usefully used as an anode current collector for a lithium secondary battery.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. To those skilled in the art. Therefore, the scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning, scope and equivalents of the claims are to be construed as being included in the scope of the present invention.

100, 200: copper foil
210, 220: Antirust film
310: active material layer
300, 400: Secondary battery electrode
340: cathode for secondary battery
370: anode for secondary battery
MS: Matte cotton
SS: Shiny Face

Claims (16)

A copper layer and an anti-corrosive film disposed on the copper layer,
A Ratio of Rmax to Thickness (RRT) of 0.11 to 0.83; And
A Ratio of Rmax to Thickness Deviation (RRTD) of 0.75 or less;
Lt; / RTI >
Here, the RRT is obtained by the following equation (1)
[Formula 1]
RRT = Rmax / T _copper
Wherein Rmax is the maximum height illuminance, T _copper is the thickness of the _copper foil;
The RRTD is obtained by the following formula 2,
[Formula 2]
RRTD = (RRTmax - RRTmin) / RRTave
In Equation 2, RRTmax is the maximum value of the RRT, RRTmin is the minimum value of the RRT, and RRTave is the average value of the RRT. The method according to claim 1,
A copper foil having a FWHM variation ratio of (220) plane of from 0.81 to 1.19 after heat treatment at 110 占 폚 for 30 minutes compared to before heat treatment;
Here, the half-value-width fluctuation rate is obtained by the following equation (3).
[Formula 3]
(Half-width after heat treatment) / (half-width before heat treatment) The method according to claim 1,
(220) plane, and the aggregate texture coefficient [TC (220)] of the (220) plane is 0.49 to 1.28. The method according to claim 1,
A copper foil having a maximum profile height (Rp) of 0.36 to 1.17 占 퐉. The method according to claim 1,
Copper foil having a weight deviation of 3% or less. The method according to claim 1,
Wherein the rustproofing film comprises at least one of chromium (Cr), a silane compound, and a nitrogen compound. The method according to claim 1,
A copper foil having a thickness of 4 탆 to 30 탆. A copper foil according to any one of claims 1 to 7, And
An active material layer disposed on the copper foil;
And an electrode for a secondary battery. A cathode;
An anode disposed opposite to the anode;
An electrolyte disposed between the anode and the cathode to provide an environment in which lithium ions can move; And
And a separator for electrically insulating the anode and the cathode,
The negative electrode,
A copper foil according to any one of claims 1 to 7, And
An active material layer disposed on the copper foil;
And a secondary battery. Polymer membrane; And
The copper foil according to any one of claims 1 to 7, which is disposed on the polymer membrane;
And a flexible copper foil laminated film. Comprising the steps of: passing a positive electrode plate and a rotating cathode drum spaced apart from each other in an electrolytic solution containing copper ions at a current density of 40 to 80 A / dm < ² > to form a copper layer;
The electrolyte solution,
70 to 90 g / L of copper ions;
50 to 150 g / L sulfuric acid;
Silver (Ag) less than or equal to 50 mg / L; And
2 to 20 mg / L allylthiourea (ATU);
Wherein the copper foil is a copper foil. 12. The method of claim 11,
Wherein the electrolytic solution contains 2 to 20 mg / L of bis (3-sulfopropyl) disulfide (SPS). 12. The method of claim 11,
And polishing the surface of the rotating cathode drum with a brush having a particle size of # 800 to # 3000 before the step of forming the copper layer. 14. The method of claim 13,
Further comprising buffing the rotary cathode drum while spraying water in a width direction of the rotary cathode drum. 12. The method of claim 11,
Wherein the electrolytic solution has a flow rate of 39 to 46 m ³ / hour. 16. The method of claim 15,
Wherein the flow velocity deviation per unit time (second and second) is 5% or less.

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