TW201937002A - Electrolytic copper foil, lithium-ion secondary cell negative electrode using electrolytic copper foil, lithium-ion secondary cell, copper-clad laminate and printed wiring board - Google Patents

Abstract

Tensile strengths respectively measured using cut copper foils, which are obtained by cutting an electrolytic copper foil from one widthwise end thereof to the other end at 100 mm intervals, satisfy the following requirements (I) through (III). Requirement (I): Under normal conditions, the average value of the tensile strengths of the cut copper foils is 400 MPa to 650 MPa. Requirement (II): Under normal conditions, dispersion [sigma]2 of the tensile strengths of the cut copper foils is 18 [MPa]2 or less. Requirement (III): The average value of the tensile strengths of the cut copper foils after being thermally treated at 150 DEG C for one hour is 350 MPa or higher.

Description

Electrolytic copper foil, and negative electrode for lithium ion secondary battery using the electrolytic copper foil, lithium ion secondary battery, copper clad laminate, and printed circuit board

The present invention relates to an electrolytic copper foil, and a negative electrode for a lithium ion secondary battery using the electrolytic copper foil, a lithium ion secondary battery, a copper-clad laminate, and a printed circuit board.

Lithium-ion secondary batteries (hereinafter sometimes referred to simply as "batteries") are composed of, for example, a positive electrode, a negative electrode, and a non-aqueous electrolyte, and are mainly used in mobile phones and laptop computers. In recent years, demand for automotive applications has also begun to grow rapidly.

The negative electrode of a lithium ion secondary battery forms a negative electrode active material layer on the surface of a negative electrode current collector. Generally, a copper foil is used for the negative electrode current collector. In particular, electrolytic copper foil (hereinafter sometimes referred to simply as "copper foil") is widely used. Compared with rolled copper foil, it is easy to have both conductivity and strength, and it can be thinned at low cost.
The negative electrode of a lithium ion secondary battery using such a copper foil is formed by applying carbon particles or the like as a negative electrode active material layer on the surface of the copper foil, drying it, and then applying pressure.

In recent years, with the expansion of the lithium-ion secondary battery market, it has become more demanding to improve battery characteristics than before, and at the same time, it has also begun to improve productivity. For these requirements, for example, in order to increase the capacity of the battery, the thickness of the active material layer is increased or the pressing pressure is increased; in order to improve the productivity, the copper foil is widened or the stripes of the active material layer are coated with multiple stripes.化 etc. In addition, it is also desired to reduce the battery weight of the lithium ion secondary battery and reduce the thickness of the copper foil.

However, in accordance with the various manufacturing conditions described above, the battery is prone to wrinkles, cracks, and poor shape of the end face of the slit when the active material layer is applied, when it is pressed, and when it is slit. The case of reduced productivity.

In addition, during charge and discharge of a lithium ion secondary battery, the active material layer may expand and contract, and the stress may be applied to other members such as a copper foil or a separator. This stress load causes the short circuit or fire due to the damage of other members such as the separator. Moreover, the stress applied to the copper foil not only causes the active material layer to peel from the copper foil, but also causes damage such as wrinkles or cracks in the copper foil, and also causes a reduction in battery life. In general, the stress applied to the copper foil further increases as the thickness or density of the active material layer increases.

In order to solve the above problems, conventional techniques have been proposed to improve the mechanical properties of copper foils, such as reducing the anisotropy of the copper foil, such as reducing the tensile strength of the copper foil to a predetermined value or more, or reducing the tensile anisotropy of the copper foil ( (See Patent Documents 1 to 4).

However, when the battery is actually manufactured, mechanical properties such as tensile strength and elongation of the copper foil are only improved, as in Patent Document 1, and the above problems cannot be sufficiently solved. In addition, as in Patent Documents 2 and 3, only the crystal grain size or orientation is controlled, or as in Patent Document 4 is only a ten-point average roughness (Rzjis) that includes only information on the two-dimensional cross-sectional shape of the surface relative to the surface. If the anisotropy of the elongation is reduced, the uneven strength due to the different positions in the wide copper foil cannot be sufficiently reduced. Especially recently, the number of cases where multiple layers of active material layers are coated on a copper foil of a wide width (for example, 600 mm or more) has begun to increase. This kind of active material layer is coated with a plurality of stripes on a wide copper foil, and is active. As the thickness or density of the material layer increases, the load applied to the copper foil also tends to increase.

In addition, recently, a copper foil having a roughened surface is used, and an adhesive resin such as epoxy resin is pasted on the roughened surface of the copper foil in advance, so that the adhesive resin is semi-hardened (B-stage) insulation. A resin layer, and the side of the insulating resin layer is the insulating substrate side, and the copper foil and the insulating substrate are thermocompression-bonded to manufacture a printed circuit board (especially a laminated circuit board).
In the manufacture of such a printed circuit board, there is a problem that wrinkles are generated on the copper foil due to the pressure applied when the copper foil and the insulating substrate are thermocompression-bonded.
Therefore, in printed circuit board applications, development of a copper foil that does not easily cause wrinkles during manufacture has also been sought.
(Previous technical literature)
(Patent Literature)

[Patent Document 1] Japanese Patent No. 5588607.
[Patent Document 2] Japanese Patent No. 5074611.
[Patent Document 3] Japanese Patent No. 5718476.
[Patent Document 4] Japanese Patent No. 6284233.

(Problem to be solved by the invention)
Therefore, an object of the present invention is to provide an electrolytic copper foil which has high mechanical strength and heat resistance, and even if it is wide, "wrinkles, cracks, and slits do not occur when a plurality of stripes are applied during battery production. "The shape of the end surface is poor." The productivity of the battery (hereinafter sometimes referred to simply as "productivity of the battery") is also excellent; and a negative electrode for a lithium ion secondary battery using the electrolytic copper foil and a lithium ion secondary battery are provided. . It is another object of the present invention to provide an electrolytic copper foil that is less prone to wrinkle due to pressurization during manufacture, even when used as a printed circuit board; a copper-clad laminated board using the electrolytic copper foil, and printing Circuit board.

(Means for solving problems)
As a result of intensive research by the inventors of the present case, it was found that the tensile strength measured by using each of the cut copper foils obtained by cutting the electrolytic copper foil from the one end in the width direction to the other end at 100 mm intervals satisfies the predetermined requirements (I) to (III) By this, an electrolytic copper foil having high mechanical strength and heat resistance and excellent battery productivity can be obtained, and the present invention has been completed. It was also found that, even if the electrolytic copper foil is used for a printed circuit board, it is difficult to generate wrinkles when pressed.

That is, the main contents of the present invention are structured as follows.
[1] An electrolytic copper foil is obtained by cutting the electrolytic copper foil from one end of the width direction to the other end at intervals of 100 mm to obtain each cut copper foil. At this time, the tensile strength measured using the cut copper foil satisfies the following The requirements (I) to (III) are mentioned.
Requirements (I): The average value of the tensile strength of each cut copper foil is 400 MPa to 650 MPa under normal conditions.
Requirements (II): The dispersion σ ² of the tensile strength of each cut copper foil in a normal state is 18 [MPa] ² or less.
Requirements (III): The average value of the tensile strength of the cut copper foils after being heat-treated at 150 ° C for 1 hour is 350 MPa or more.
[2] The electrolytic copper foil according to the above [1], whose width dimension is 600 mm or more.
[3] The electrolytic copper foil according to the above [1] or [2], wherein the average value of the elongation of each cut copper foil in a normal state is 5.3% or more.
[4] The electrolytic copper foil according to any one of the above [1] to [3], having a conductivity of 88% IACS or more.
[5] The electrolytic copper foil according to any one of the above [1] to [4], wherein the developed area ratio (Sdr) of the glossy surface is 12% or more and 27% or less.
[6] The electrolytic copper foil according to any one of the above [1] to [5], which is used as a negative electrode current collector of a lithium ion secondary battery.
[7] A negative electrode for a lithium ion secondary battery using the electrolytic copper foil as described in [6] above.
[8] A lithium ion secondary battery using the negative electrode for a lithium ion secondary battery as described in [7] above.
[9] An electrolytic copper foil having a roughened surface on at least one surface of the electrolytic copper foil according to any one of the above [1] to [5], and a developed area ratio of the roughened surface (Sdr) is 20% to 200%.
[10] A copper-clad laminated board comprising the electrolytic copper foil as described in the above [9] and a resin substrate laminated on a roughened surface of the electrolytic copper foil.
[11] A printed circuit board comprising the copper-clad laminated board as described in [10] above.

(Effect of the invention)
According to the present invention, it is possible to provide an electrolytic copper foil having high mechanical strength and heat resistance and excellent battery productivity even in a wide range, and a negative electrode for lithium ion secondary batteries and lithium ion using the electrolytic copper foil. Secondary battery. Furthermore, according to the present invention, it is possible to provide an electrolytic copper foil that is less prone to wrinkle due to pressurization during manufacture, a copper-clad laminated board using the electrolytic copper foil, and a printed circuit board, even when used in a printed circuit board application. .

Hereinafter, embodiments of the electrolytic copper foil according to the present invention will be described in detail.

The electrolytic copper foil of the present invention is characterized in that each cut copper foil is obtained by cutting at an interval of 100 mm from one end to the other end in the width direction. At this time, the tensile strength measured using the cut copper foil satisfies the following requirements. (I) to (III).
Requirements (I): The average value of the tensile strength of each cut copper foil is 400 MPa to 650 MPa under normal conditions.
Element (II): The dispersion σ ² of the tensile strength of each cut copper foil in a normal state is 18 [MPa] 2 or less.
Requirements (III): The average value of the tensile strength of the cut copper foils after being heat-treated at 150 ° C for 1 hour is 350 MPa or more.

In addition, in this specification, "electrolytic copper foil" refers to a copper foil produced by electrolytic treatment, and means an untreated copper foil that is not subjected to a surface treatment after the production of the foil, and a copper foil that is subjected to a surface treatment as required ( Surface treated electrolytic copper foil). The thickness of the electrolytic copper foil is preferably 30 μm or less, and more preferably 4 to 15 μm. In addition, unless otherwise stated, "copper foil" means "electrolytic copper foil".

The "width direction" of the copper foil is a direction perpendicular to the conveying direction (same as the direction of peeling from the cathode electrode) when the copper foil is manufactured. When the copper foil is wound into a roll shape, its long side Corresponds to the transport direction. The "widthwise dimension" is a dimension from one end to the other end in the width direction of the copper foil.

The "cut copper foil" refers to a copper foil obtained by cutting a copper foil at an interval of 100 mm from one end in the width direction to the other end. Here, the cut copper foil used to evaluate the characteristics of the copper foil is a whole cut copper foil with a width dimension of 100 mm (± 5 mm), and a cut copper foil with a width dimension of less than 95 mm is not a measurement object. For example, in the case of copper foil with a width dimension of 850mm, if it is cut at an interval of 100mm from one end to the other end in the width direction, 9 pieces of cut copper foil can be obtained, and the width dimension as the measurement object is 100mm ( ± 5mm) of 8 pieces of cut copper foil.

The "normal state" refers to a state that does not have a thermal history accompanying heating beyond 60 ° C except for the unheated state after the copper foil is produced, and is, for example, a state where it is left at room temperature (15 to 30 ° C, the same applies hereinafter). The "state after heat treatment at 150 ° C for 1 hour" refers to a state where the copper foil is heat-treated at 150 ° C for 1 hour and cooled to room temperature, for example.

Conventional high-strength copper foils have problems such as wrinkles, cracks, and poor shapes of the end faces of slits when a plurality of stripes are applied to a wide copper foil. In view of these problems, the inventors of the present invention conducted intensive studies and confirmed that the occurrence of the above problems is related to the degree of uneven tensile strength in the width direction of the copper foil.

Generally, the stripe coating has a structure in which a place where an active material layer is applied and an uncoated place are alternately formed in the width direction of the copper foil, and a place where a load is applied and a place where no application is applied alternately in the width direction of the copper foil. In the case where the stripe-coated copper foil is pressurized or slitted during the production line, it can be seen that if there is unevenness in tensile strength in the width direction of the copper foil, it is easy to send the Unsmoothness, sliding in the width direction of copper foil, and fluctuation in tension. In particular, it can be seen that irregularities in the transportation of the production line and sliding in the width direction of the copper foil can cause wrinkles or fractures, and tension changes can cause wrinkles or abnormalities in the end faces of the slits (burrs, cracks, etc.).

Based on the above findings, the present invention has found a copper foil with high strength and excellent heat resistance. In particular, by reducing the variation in tensile strength in the width direction of the copper foil compared to conventional high-strength copper foils, The above problems can be solved, and the productivity in the battery mass production step can be improved.

In addition, as a result of intensive investigations on the defect of the pressurization step of the printed circuit board by the inventors of the present invention, it was confirmed that the larger the unevenness of the tensile strength of the copper foil, the more easily wrinkles are generated.
Based on the above findings, it has been found that, as described above, the variation in tensile strength in the width direction is reduced for the copper foil used for a printed circuit board, thereby suppressing wrinkle defects and improving the productivity of the printed circuit board.

The width dimension of the copper foil of the present invention is preferably 300 mm or more, more preferably 600 mm or more, even more preferably 900 mm or more, and even more preferably 1200 mm or more. This copper foil is suitable for mass production of batteries or printed circuit boards. The upper limit of the width dimension of the copper foil varies depending on the manufacturing equipment of the copper foil, and is, for example, 2000 mm. From the viewpoint of reducing unevenness in the width direction, the width dimension of the copper foil is preferably 1500 mm or less.

From the standpoint of mass production of batteries or printed circuit boards, the larger the copper foil in the width direction is, the more suitable it is. However, when a battery or a printed circuit board is manufactured, the applied stress tends to be different in the width direction of the copper foil. Therefore, especially for a wide copper foil, the above-mentioned problems become obvious. However, in the present invention, the unevenness of the tensile strength in the width direction of the copper foil is reduced to solve the above-mentioned problems.

In the present invention, in order to properly evaluate the characteristic unevenness in the width direction of the copper foil, various measurements are performed using each cut copper foil obtained by cutting the copper foil from one end of the width direction to the other end at intervals of 100 mm. Finally, it evaluated as the whole copper foil. Each element is explained in detail below.

<Requirement (I)>
In the copper foil of the present invention, the average value of the tensile strength (Ts) of each cut copper foil under normal conditions is 400 MPa to 650 MPa, preferably 400 MPa to 600 MPa, more preferably 445 MPa to 600 MPa, and even more preferably 450 MPa or more. 600 MPa or less. By making it into the said range, the productivity of a battery can be improved and a battery with favorable battery characteristics can be manufactured. On the other hand, when the average value of the tensile strength of each cut copper foil is less than 400 MPa under normal conditions, it cannot bear the effect of an increase in load caused by the electrode material accompanying the increase in capacity of the battery. Wrinkle tendency. When the average tensile strength of each cut copper foil exceeds 650 MPa in the normal state, the elongation of the copper foil is reduced, and the copper foil tends to be easily broken.
Moreover, when it is used for a printed circuit board, and when the tensile strength of a copper foil in a normal state is less than 400 MPa, wrinkles generate | occur | produce at the time of conveying a thin foil product, and handling property will worsen. Further, when the tensile strength of the copper foil in a normal state exceeds 650 MPa, the foil breaks easily during the precipitation manufacturing using a drum, and the productivity is deteriorated.

<Requirement (II)>
The dispersion σ ² of the tensile strength (Ts) of each cut copper foil of the present invention under normal conditions is 18 [MPa] ² or less, preferably 14 [MPa] ² or less, and more preferably 11 [MPa] ² or less. , And more preferably 10 [MPa] ² or less. Here, the dispersion of the tensile strength of each of the cut copper foils is an index of uneven tensile strength in the width direction of the σ ² based copper foil, and a larger value indicates an uneven tensile strength. By making the dispersion σ ² of the tensile strength of each cut copper foil of the copper foil of the present invention in the normal state within the above range, it is possible to effectively prevent the occurrence of local wrinkles or sags during the manufacturing process of the electrode. In addition, wrinkles can be effectively prevented from occurring due to pressure during the manufacturing process of the printed circuit board. On the other hand, when the dispersion σ ² of the tensile strength of each cut copper foil is more than 18 [MPa] ² under normal conditions, the tensile strength of the copper foil in the width direction is not uniform. The stress on the copper foil is uneven in the width direction of the copper foil, so local wrinkles or sags occur, and the productivity of the battery tends to decrease. Moreover, in the manufacturing process of a printed circuit board, there is also a tendency that the occurrence of wrinkles due to pressure becomes obvious. In addition, the lower limit of the dispersion σ ² of the tensile strength of each cut copper foil in a normal state may be, for example, 0 [MPa] ² .

<Requirement (III)>
In the copper foil of the present invention, the average value of the tensile strength (Ts) of each of the cut copper foils after being heat-treated at 150 ° C for one hour is 350 MPa or more, preferably 380 MPa or more, and more preferably 400 MPa or more. By setting it within the above range, sufficient strength can be maintained when the battery is processed, and the durability of the load when the battery is charged and discharged is excellent, thereby improving the cycle life of the battery. On the other hand, if the average tensile strength of each cut copper foil is less than 350 MPa after heat treatment at 150 ° C for 1 hour, the strength will be reduced when the battery is processed, and it will not be able to withstand the charge and discharge of the battery. The load tends to cause the copper foil to break, and the cycle life of the battery tends to decrease. In addition, the upper limit of the average value of the tensile strength of each cut copper foil in a state of being heat-treated at 150 ° C for 1 hour may be, for example, 550 MPa, preferably 450 MPa, from the viewpoint of having a moderate elongation after heating. .
In the manufacture of printed circuit boards, when the average tensile strength of each cut copper foil is 350 MPa or more in a state of being heat-treated at 150 ° C for 1 hour, it may be applied after heating in the substrate lamination step. Since the crystal grains are finely maintained, the etchability becomes good. On the other hand, when the average value of the tensile strength is less than 350 MPa, the crystal grains tend to become larger after heating in the lamination step of the substrate, and it is difficult to dissolve the copper particles by etching, so the etching properties are deteriorated.

In addition, in the requirements (I) to (III), the tensile strength is a value measured under the evaluation conditions described in this example.

＜ Extension （El） ＞

In the copper foil of the present invention, the average value of the elongation (El) of each cut copper foil in the normal state is preferably 5.3% or more, more preferably 6.0% or more, even more preferably 7.5% or more, and even more preferably 9.0% or more. . By making it into the said range, durability of the stress applied to a copper foil at the time of battery charge and discharge improves. In addition, from the viewpoint of high strength, the upper limit of the average value of the elongation of each cut copper foil under normal conditions may be, for example, 13.0%, and preferably 11.0%.
The average value of the elongation of each cut copper foil in the state after the heat treatment at 150 ° C. for 1 hour is preferably in the same range as in the normal state.
The elongation is a value measured under the evaluation conditions described in this example.

<Expansion area ratio (Sdr)>
In the past, the ten-point average roughness Rzjis was generally used as a parameter indicating the surface shape of the copper foil. However, the ten-point average roughness Rzjis only contains information on the two-dimensional cross-sectional shape of the surface in the height direction, and cannot be accurately evaluated. In contrast, the developed area ratio (Sdr) includes three-dimensional information of the surface, and more appropriate characteristic evaluation can be performed.

The expanded area ratio (Sdr) means the ratio of the area increased by the surface property based on the ideal surface having the size of the measurement area, and it is defined by the following formula (1).

In the above formula (1), x and y are plane coordinates, and z is a coordinate in the height direction. z (x, y) represents the coordinates of a point, and by differentiating it, it becomes the slope in the coordinate point. A is the flat area of the measurement area.

The developed area ratio (Sdr) can be obtained by measuring the unevenness on the surface of the copper foil by, for example, measuring a three-dimensional white interference microscope, a scanning electron microscope (SEM), or an electron beam three-dimensional roughness analysis device, and then evaluating it. . Generally speaking, the development area ratio (Sdr) has nothing to do with the change in surface roughness (Sa), but the spatial complexity of the surface texture tends to increase.

The expanded area ratio (Sdr) of the glossy surface of the copper foil of the present invention is preferably 27% or less, more preferably 20% or less, even more preferably 18.5% or less, still more preferably 17% or less. By making it into the said range, the intensity | strength unevenness of the copper foil in the width direction can be reduced further, and the productivity of a battery can be improved further. Moreover, by making it into the said range, generation | occurrence | production of a wrinkle by pressurization can also be suppressed in the manufacturing process of a printed wiring board. In addition, the lower limit of the developed area ratio (Sdr) of the glossy surface may be, for example, 12% from the viewpoint of the coatability of the active material layer.
In addition, the copper foil of the present invention preferably has a developed area ratio (Sdr) of rough surface of 92% or less, more preferably 90% or less, even more preferably 80% or less, and even more preferably 70% or less. By making it into the said range, coating of an active material layer becomes uniform at the time of manufacture of an electrode, and the stress load to a copper foil is uniformly produced | generated thereby, wrinkles or slackness are reduced, and productivity improves. Moreover, by making it into the said range, generation | occurrence | production of a wrinkle by pressurization can also be suppressed in the manufacturing process of a printed wiring board. In addition, the lower limit of the spread area ratio (Sdr) of the rough surface may be, for example, 62%.
Here, the developed area ratio (Sdr) of the glossy surface and the roughened surface is a value measured under the evaluation conditions described in this example.
In addition, the glossy surface ("sometimes also referred to as the" S (bright) surface ") refers to the surface on the contact side with the cathode drum during the production of electrolytic copper foil, and the rough surface (also sometimes referred to as" the M (matte) surface ") means the surface opposite to the glossy surface. In addition, in the specification of the present application, when it is referred to as a glossy surface and a rough surface, it refers to an untreated copper foil surface that has not been subjected to a surface treatment after the production of the foil. The roughened surface of the roughening process is different.

The copper foil of the present invention may have a roughened surface on at least one side of the copper foil, and the developed area ratio (Sdr) of the roughened surface is preferably 20% or more and 200% or less, and more preferably 25% or more. Below 197%. This copper foil is particularly suitable for use as a printed circuit board. For example, when the developed area ratio (Sdr) of the roughened surface is less than 20%, the adhesiveness tends to decrease when the resin is adhered to the surface, and when it exceeds 200%, the etching factor has an etching factor. It is reduced, and it is difficult to form fine wiring.
The developed area ratio (Sdr) of the roughened surface is a value measured under the evaluation conditions described in this example.

＜ Conductivity ＞
The electrical conductivity of the copper foil of the present invention is preferably 88% IACS or more, more preferably 90% IACS or more, even more preferably 91% IACS or more, and even more preferably 92% IACS or more. By setting it within the above range, the internal resistance of the negative electrode is reduced when the battery is manufactured, and the cycle characteristics of the battery are improved. Moreover, if it is in the said range, a copper foil is also suitable for a printed circuit board.
Here, the electrical conductivity is a value measured under the evaluation conditions described in this example.

<Manufacturing method of electrolytic copper foil>
Next, a preferred method for producing the electrolytic copper foil of the present invention will be described.
The electrolytic copper foil of the present invention can be produced, for example, by supplying an electrolytic solution to an insoluble anode made of titanium covered with a platinum group element or an oxide element thereof, and made of titanium provided to face the anode. Between the cathode drums, while the cathode drum is rotating at a certain speed, a direct current is passed between the two poles, thereby causing copper to precipitate on the surface of the cathode drum, and the precipitated copper is peeled from the surface of the cathode drum, and continuously Coiled. The device manufactured in this manner is an example.

As the electrolytic solution, for example, a sulfuric acid-copper sulfate aqueous solution having a copper concentration of 50 to 100 g / L and a sulfuric acid concentration of 40 to 120 g / L is suitably used.

From the viewpoint of increasing the strength of the copper foil, at least one of organic and inorganic additives may be added to the electrolytic solution.
As the organic additive, for example, thiourea (CH ₄ N ₂ S) or a water-soluble thiourea derivative (ethylthiourea, etc.), and viscose, gelatin, polyethylene glycol, starch, and cellulose-based water-soluble can be used. High molecular polysaccharides such as molecules (carboxymethyl cellulose, hydroxyethyl cellulose, etc.), water-soluble polymer compounds such as polyethyleneimine, polypropylene amidamine, and the like.
In addition, as the inorganic additive, in addition to NaCl or HCl as a supply source of chloride ions, a trace amount of sodium tungstate, ammonium tungstate, or the like may be used as a supply source of a metal element.

In the electrolytic solution, 1 to 30 mg / L of chloride ion is preferably added as an inorganic additive, and 3 to 19 mg / L of thiourea or a water-soluble thiourea derivative is preferably added as an organic additive.
The temperature of the electrolytic solution is preferably adjusted to 40 to 60 ° C, and the average current density on the cathode electrode surface is preferably adjusted to 40 to 60 A / dm ² .

In addition, the increase in strength of a copper foil is generally performed by adding an additive to an electrolytic solution. The effect of the additive is mainly to make the additive adsorb on the crystal nucleus of the copper surface layer in the electrodeposition, thereby controlling the inhalation of impurities in the foil, or controlling the crystal orientation and crystal grain size.
However, the generation ratio of nucleation and nucleus growth varies depending on manufacturing conditions such as the concentration of the electrolyte, the current density, the temperature of the liquid, the type of additive, and its concentration. In particular, under conditions where the purpose is to increase strength, nuclear growth has become dominant in many cases.
Additives are adsorbed on copper grains and sucked into the copper foil, which can increase the strength of the copper foil, but the core growth is dominant, which means that the adsorption points of the additives tend to become sparse. The high-strength copper foil produced under such conditions is liable to cause uneven strength.

In the present invention, it has been found that, for example, by making the initial electrical coating of copper fine and smooth by using the following method, the adsorption points of the additives can be made uniform in the plane direction of the copper foil, thereby reducing the Uneven tensile strength.
Specifically, it is preferable to use a PR (Periodic Reverse) pulse electrolysis only in the initial electrocoating on the basis of a conventional foil-making step.

In the conventional case where a direct current foil is used, a copper core is generated on a cathode substrate, and copper is grown from this core.
However, by using PR pulse electrolysis in the initial electrocoating, the copper precipitation step (when a positive pulse is energized) and the dissolution step (when a negative pulse is energized) are repeated during the formation of copper crystal nuclei. The crystal nucleus of copper generated in the precipitation step is reduced in size by a subsequent dissolution step. In the precipitation step subsequent to the dissolving step, in addition to the smaller copper crystal nuclei, new copper crystal nuclei are further formed on the cathode substrate. By repeating these steps, fine nucleation can be obtained, and the initial electrical coating can be made finer and smoother. As a result, it is considered that the adsorption points of the additives can be obtained uniformly.

Suitable conditions for PR pulse electrolysis are described below.
Positive pulse current density I _on : 20 ～ 80A / dm ²
Positive pulse energization time t _on : 50 ～ 200 milliseconds (ms)
Negative pulse current density I _rev : －80 ～ －20A / dm ²
Negative pulse energization time t _rev : 50 ～ 200 milliseconds (ms)
Pulse stop time t _off : 50 ～ 200 milliseconds (ms)
Positive pulse-negative pulse repetition times: 10 ～ 30 times

In the PR pulse electrolysis, particularly from the viewpoint of obtaining a homogeneous coating of the initial electrical point of view, the positive pulse current density I _on (A / dm ²⁾ with the positive pulse energization time t _on (ms) calculated by the product of The positive pulse cumulative current value Q1 (= I _on × t _on ) and the negative pulse cumulative current value Q2 (calculated from the product of the negative pulse current density I _rev (A / dm ² ) and the negative pulse energization time t _rev (milliseconds). = I _rev × t _rev ) preferably satisfy the relationship of the following formula (i).
0.5 ≦ | Q2 ／ Q1 | ≦ 0.9 ･ ･ ･ ･ ･ (i)

When the absolute value of the ratio of the negative pulse cumulative current value Q2 to the positive pulse cumulative current value Q1 | Q2 / Q1 | is greater than 0.9, the dissolution step has a large effect and the total amount of copper nucleation becomes insufficient. Also, when it is less than 0.5, the effect of the precipitation step is large, and it is difficult to obtain fine nucleation.

According to the above method, an extremely thin and homogeneous initial electrical coating layer can be formed to a minimum, whereby a uniform precipitation layer can be obtained in the thickness direction of the copper foil in the subsequent steps. Therefore, the additive is uniformly adsorbed on both sides of the copper foil in the surface direction and the thickness direction, and the strength unevenness in the width direction is small, so that a high-strength electrolytic copper foil can be obtained.

In addition, as a device suitable for manufacturing the copper foil by the above method, a manufacturing device such as that shown in FIG. 1 can be exemplified. FIG. 1 shows a schematic view of a manufacturing apparatus.
As shown in FIG. 1, the manufacturing apparatus 1 mainly includes a cathode drum 11, a PR pulse electrode 12, an anode 13, and a bath 14. The PR pulse electrode 12 and the anode 13 are provided so as to face the cathode drum 11, and an electrolytic solution 20 is supplied therebetween. The cathode drum 11 is rotated at a constant speed in the direction of the arrow 11a, and a PR pulse and a direct current are passed between the two poles of the PR pulse electrode 12 and the anode 13, respectively, thereby depositing copper on the surface of the cathode drum 11. The copper deposited on the surface of the cathode drum 11 was finally peeled off in the direction of the arrow 30 a, and the copper foil was formed as a copper foil 30. In addition, in the manufacturing apparatus 1, the illustration of the outside of the bath 14 and various pipes and the like is omitted. The electrolytic solution 20 is continuously supplied from the outside of the bath 14 in the direction of the arrow 20a, and has passed through the cathode drum 11 and the PR. The electrolytic solution 20 between the pulse electrode 12 and the anode 13 is discharged to the outside of the bath 14 through a discharge pipe.

The electrolytic copper foil of the present invention may be further subjected to a surface treatment on at least one side of the surface of the copper foil as required.
As the surface treatment of the copper foil, for example, chromate treatment, or Ni or Ni alloy plating, Co or Co alloy plating, Zn or Zn alloy plating, Sn or Sn alloy plating, and various plating layers described above Further, an inorganic rust prevention treatment such as chromate treatment, an organic rust prevention treatment such as benzotriazole, a silane coupling agent treatment, and the like are further performed. In addition to rust prevention, these surface treatments, for example, when used as a negative electrode current collector of a lithium-ion secondary battery, play a role of improving the adhesion strength with an active material and further preventing a decrease in the charge and discharge cycle efficiency of the battery. . These rust prevention treatments are generally treated with an extremely thin thickness relative to the thickness of the copper foil. Therefore, the tensile strength and the like are hardly affected.

Before performing the above-mentioned surface treatment on the copper foil, the surface of the copper foil may be roughened as required. As the roughening treatment, for example, a plating method, an etching method, or the like is suitably used. These roughening treatments, when copper foil is used as a negative electrode current collector of a lithium ion secondary battery, can play a role of further improving adhesion to an active material and the like. Moreover, when a copper foil is used for manufacture of a printed circuit board, roughening process also plays the role which improves the adhesiveness with an insulating substrate. In addition, in the production of printed circuit boards, from the viewpoint of forming fine circuits well, it is desirable to control the roughening treatment to form a desired surface texture, especially a roughened surface having an expected spreading area ratio (Sdr). The roughening treatment is generally performed with a very thin thickness relative to the thickness of the copper foil. Therefore, it hardly affects the tensile strength and the like.

As the roughening by the plating method, a plating method and an electroless plating method can be used. Coarse particles can be formed by metal plating composed of one metal among Cu, Co, and Ni, or alloy plating including two or more of these metals.

The roughening by the etching method is preferably a method by physical etching or chemical etching, for example. For example, as the physical etching, a method of performing etching by a sandblast method or the like is mentioned. Moreover, as a chemical etching, the method of performing an etching with a processing liquid etc. is mentioned. Particularly in the case of chemical etching, as the processing liquid, a conventional processing liquid containing an inorganic or organic acid, an oxidizing agent, and an additive can be used.

Hereinafter, a preferable example of roughening by a plating method will be specifically described.
Roughening treatment can be performed on at least one surface of a copper foil (hereinafter referred to as "copper foil base material") as a base material in order to perform a roughening treatment 1 and a roughening treatment 2. . The preferable conditions of the roughening plating process 1 and the roughening plating process 2 are as follows. In addition, the following conditions are preferred examples, and the types, amounts, and electrolytic conditions of the additives may be appropriately changed and adjusted in accordance with the requirements, as long as the effects of the present invention are not hindered.

Rough plating treatment 1
Copper sulfate: 18 ～ 23g / L based on copper concentration
(It means "the amount of copper metal is equivalent to 18-23 g / L of copper sulfate"; the same shall apply hereinafter).
Sulfuric acid: 96 ～ 105g / L
Cobalt (II) sulfate heptahydrate: 2.8 ～ 4.2g / L based on cobalt concentration
Liquid temperature: 32 ～ 40 ℃
Current density: 32 ～ 36A / dm ²
Time: 1 second to 2 minutes

Rough plating treatment 2
Copper sulfate: 45 ～ 55g / L based on copper concentration
Sulfuric acid: 112 ～ 121g / L
Liquid temperature: 59 ～ 64 ℃
Current density: 6 ～ 12A / dm ²
Time: 1 second to 2 minutes

In particular, when the copper foil of the present invention is used for a printed circuit board, the roughened surface of the copper foil is unrolled from the viewpoint of both the adhesion to the insulating substrate and the formation of fine microcircuits. It is very effective to control the area ratio (Sdr) within the range of 20% to 200%. By satisfying the above-mentioned conditions for the roughening treatment, such a roughened surface having desired surface properties can be produced.

In addition, when the surface treatment is performed after the roughening treatment, since the surface treatment such as rust prevention treatment is performed with an extremely thin thickness, it hardly affects the developed area ratio (Sdr) of the roughened surface. . Therefore, after the surface treatment such as the rust prevention treatment, the spread area ratio (Sdr) of the roughened surface adjusted by the roughening treatment can be maintained.

<Negative electrode for lithium ion secondary batteries and lithium ion secondary batteries>
The copper foil according to the present invention is preferably used as a negative electrode current collector of a lithium ion secondary battery. By using the copper foil of the present invention, even when a plurality of stripes are applied when manufacturing a battery, wrinkles, fractures, and defective shapes of the slit end faces are not easily generated, and the productivity of the battery can be improved.
The negative electrode for a lithium ion secondary battery using the copper foil according to the present invention as a negative electrode current collector has high strength and high heat resistance, and therefore, durability during battery manufacturing and charge / discharge is improved. In addition, a lithium ion secondary battery using such a negative electrode has a good yield at the time of manufacture, and also has excellent battery characteristics (for example, cycle characteristics).

The negative electrode for a lithium ion secondary battery can be formed by a conventional method using the copper foil of the present invention. For example, a slurry containing carbon particles or the like as a negative electrode active material layer can be coated on the surface of a copper foil, dried, and further pressurized to form a negative electrode for a lithium ion secondary battery.

The lithium ion secondary battery can be formed by a conventional method using the negative electrode described above.

＜ Copper-clad laminated board and printed circuit board ＞
The copper foil according to the present invention can also be used as a copper-clad laminated board and a printed circuit board provided with the same. By using the copper foil of the present invention, when manufacturing a printed circuit board, it is possible to suppress the occurrence of wrinkles due to the pressure when the copper foil and the insulating substrate are subjected to thermal compression bonding, and the production of the printed circuit board can be improved. Sex.

The copper foil of the present invention for manufacturing a printed circuit board preferably has a roughened surface on at least one surface of the copper foil, and the developed area ratio (Sdr) of the roughened surface is 20% to 200%. the following. According to such a copper foil, it is possible to suppress wrinkle defects due to pressurization, and also to form a good fine wiring.

The copper-clad laminated board is preferably a resin substrate provided with the copper foil of the present invention and a roughened surface laminated on the copper foil. Such a copper-clad laminated board can be formed by a conventional method using the copper foil of the present invention. For example, a copper foil having a roughened surface on at least one surface and an insulating substrate (resin substrate) are laminated and pasted so that the roughened surface (adhesive surface) and the resin substrate face each other. Manufacture of copper clad laminates. Examples of the insulating substrate include a flexible resin substrate and a rigid resin substrate. The copper foil of the present invention is particularly suitable for combination with a rigid resin substrate.

In addition, in the case of manufacturing a copper-clad laminated board, the surface-treated copper foil having a silane coupling agent layer and an insulating substrate may be bonded together by hot pressing, thereby manufacturing. In addition, a silane coupling agent is coated on the insulating substrate, and the insulating substrate coated with the silane coupling agent is bonded to a surface-treated copper foil having a rust-proof treatment layer on the outermost surface by hot pressing. It has the same effect as the present invention.

Moreover, it is preferable that a printed wiring board is provided with the said copper clad laminated board. Such a printed circuit board can be formed by a conventional method using the above-mentioned copper-clad laminated board.

In addition, among printed circuit boards, it is also expected that various electronic components are highly integrated. In response to this, high density of wiring patterns is also required, and wiring with fine line widths and pitches is being sought. A pattern, a so-called fine pattern printed circuit board. For example, multilayer substrates for servers, routers, communication base stations, and automotive substrates, or multilayer substrates for smartphones, require printed circuits with high-density, ultra-fine wiring (hereinafter referred to as "high-density circuit boards"). ).

High-density circuit boards of AnyLayer (connected between laser vias with a high degree of freedom of configuration) are mainly used for smart phone motherboards. However, in recent years, fine wiring has been developed to seek line width and line spacing. (Hereinafter referred to as "L &S".) The wiring is 30 μm or less. Conventionally, printed circuit board manufacturers have manufactured high-density circuit boards using a subtractive method of photoresistance. It has been known that the thickness of copper foil is very effective for miniaturizing L & S and reducing the thickness of copper foil. However, in the case of forming a high-density circuit board at a large area of more than 500 × 500 mm ² at a time, if the thickness is 9 μm or less, the insulating resin and the copper foil are pressed, and the copper Wrinkle problem.

For such a problem, for example, Japanese Patent No. 6158573 discloses a technique for forming fine wiring by minimizing the average crystal grain size of a large number of extremely thin copper layers. However, since no countermeasures against wrinkles have been taken, copper In the case where the foil is thin, defects often occur in the pressing step.

In contrast, the copper foil of the present invention has a small uneven tensile strength in the width direction as described above. Therefore, even in a case where the high-density circuit board is formed at one time by thinning, the occurrence of the pressing step can be suppressed Wrinkles are not good, and productivity can be improved in the manufacture of high-density circuit boards.

As mentioned above, although embodiment of this invention was described, the said embodiment is only an example of this invention. The present invention includes all aspects of the concept of the present invention and the scope of patent application, and various changes can be made within the scope of the present invention.

(Example)
The following examples illustrate the invention in further detail, and the following is an example of the invention.

(Production Examples 1 to 9 and Comparative Production Examples 1 to 4)
As shown in FIG. 1, an electrolytic solution 20 is supplied between a titanium cathode drum 11 (with a width of 1200 mm and a diameter of 2100 mm) and a PR pulse electrode 12 and an insoluble anode 13 provided to face the cathode drum 11. The cathode drum 11 is rotated at a constant speed, and while a PR pulse and a direct current are passed between the poles, copper is precipitated on the surface of the cathode drum 11 to produce a copper foil 30 having a thickness of 10 μm. Thereafter, the copper foil 30 was peeled from the cathode drum 11, and both ends were cut and wound into a roll shape to obtain a copper foil with a width dimension of 1100 mm.

For each of Production Examples 1 to 9 and Comparative Production Examples 1 to 4, the electrolytic solution 20 was prepared using sulfuric acid-sulfuric acid prepared at a copper concentration of 80 g / L, sulfuric acid concentration of 100 g / L, and chloride ion concentration of 20 mg / L Copper-based electrolyte. The temperature of the electrolytic solution was adjusted to 55 ° C., the average current density was 45 A / dm ² , and the liquid flow rate was adjusted to 1.0 m / s.

In addition, the manufacturing examples 1 to 9 and comparative manufacturing examples 1 to 4 were adjusted as shown in Table 1 with respect to the types of additives added to the electrolytic solution, their added concentrations, and the electrolytic conditions of PR pulse electrolysis. The rotation speed of the cathode drum 11 is appropriately adjusted in accordance with the electrolytic conditions so that the thickness of the copper foil 30 is 10 μm.
In addition, among the types of additives described in Table 1, "thiourea" and "ethylthiourea" are both products of Tokyo Chemical Industry Co., Ltd.

(Comparative Manufacturing Example 5)
In Comparative Example Production 5, a copper foil 30 was obtained in the same manner as in Production Example 1 except that copper was not deposited on the surface of the cathode drum 11 by applying a PR pulse between the electrodes.

(Comparative Manufacturing Example 6)
In Comparative Production Example 6, a copper foil 30 was obtained in the same manner as in Production Example 2 except that copper was not deposited on the surface of the cathode drum 11 by applying a PR pulse between the electrodes.

(Table 1)

(Examples 1 to 9 and Comparative Examples 1 to 6)
(Characteristic evaluation)
About the copper foil produced by the said manufacturing example and the comparative manufacturing example, the characteristic evaluation shown below was performed. The evaluation conditions of each characteristic are as follows. Unless otherwise specified, each measurement is performed at room temperature. The results are shown in Table 2.

＜ Production of cut copper foil ＞
As the normal state copper foil, the produced unheated copper foil was used as it is.
In addition, the copper foil in the state after being heat-treated at 150 ° C for 1 hour was heated at 150 ° C for 1 hour in a normal state using an inert gas oven (INH-21CD-S, manufactured by Koyo Thermo Systems Co., Ltd.). Cool the copper foil to room temperature.
Each copper foil was cut at a distance of 100 mm from one end to the other end in the width direction to obtain 11 pieces of cut copper foil (100 mm × 200 mm, thickness 10 μm) corresponding to each state.

＜ tensile test ＞
A tensile tester (type 1122, manufactured by Instron) was used as a measurement object, and two types of cut copper foils were heat-treated at 150 ° C for 1 hour, and the tensile test was performed in accordance with the regulations of IPC-TM-650.
First, starting from a position of 10 mm from one end (cutting end) in the width direction of a cut copper foil, five test pieces (0.5 inch × 6 inch) with a width dimension of 0.5 inch were cut out at a distance of about 5 mm in the width direction. ). Using the obtained test piece, the tensile strength and elongation were measured under the conditions of a chuck pitch of 70 mm and a tensile speed of 50 mm / min. Here, the elongation refers to the elongation when the test piece is broken. Then, an average value calculated from the obtained measurement values (N = 5 each) is taken as the tensile strength and elongation of the one-cut copper foil. Furthermore, the tensile strength and elongation of each of the other 10 cut copper foils were similarly determined. Finally, the tensile strength and elongation (n = 11) of each of the 11 cut copper foils were averaged. The average tensile strength and the average elongation were determined.
This measurement was performed separately for two kinds of copper foils in a normal state and a state after heat treatment at 150 ° C for 1 hour.
In addition, for a normal copper foil, the tensile strength dispersion σ ^{2 was} obtained from the tensile strength of each of the 11 cut copper foils.

<Expansion area ratio (Sdr)>
The developed area ratio (Sdr) was measured using a normal-cut copper foil as a measurement object, and a white light interference type optical microscope (Wyko Contour GT-K, manufactured by BRUKER) was used to measure the surface shape, and then measured by shape analysis. The shape analysis system uses a high-resolution CCD camera in the VSI measurement method. The light source is white light, the measurement magnification is 50 times, the measurement area is 96.1 μm × 72.1 μm, Lateral Sampling is 0.075 μm, speed is 1, Backscan is 10 μm, and Length It was performed under the conditions of 10 μm and Threshold of 3%, and processed with filters of Terminal Removal (Cylinder and Tilt), Data Restore (Method: legacy, iterations 5), and then data processing. Specifically, it is performed as follows.
First, the shape of the surface was measured at the center of a cut copper foil, and the shape analysis was performed to determine the developed area ratio (Sdr). Furthermore, the developed area ratio (Sdr) was measured similarly for the other 10 pieces of cut copper foil. Finally, the measured values (N = 11) of the developed area ratio (Sdr) of each 11 pieces of cut copper foil were averaged and averaged. The value is taken as the spread area ratio (Sdr) of the copper foil. The results are shown in Table 2.

＜ Conductivity ＞
The electrical conductivity is measured using a normally-cut copper foil, and an Agilent 4338B Milliohm Meter (manufactured by Agilent Technologies, Inc.) is used to measure the electrical conductivity in accordance with JIS H 0505-1975. Specifically, it is performed as follows.
A test piece (0.5 inch × 6 inch) was cut out from a cut copper foil, and the test piece was used to make the distance between terminals 100 mm, and the conductivity was measured three times by the 4-terminal method. The average value calculated from the obtained measurement values (N = 3) was taken as the electrical conductivity of the one-cut copper foil. In addition, the electrical conductivity was calculated similarly for the other 10 cut copper foils. Finally, the electrical conductivity (N = 11) of each of the 11 cut copper foils was averaged, and the average value was used as the electrical conductivity of the copper foil. The results are shown in Table 2.

(Evaluation of lithium ion secondary battery applications)
The copper foil produced by the said manufacturing example and the comparative manufacturing example was used as a negative electrode current collector, the lithium ion secondary battery was produced, and the characteristic evaluation shown below was performed. The evaluation conditions of each characteristic are as follows. Unless otherwise specified, each measurement is performed at room temperature. The results are shown in Table 2.

(Manufacturing of positive electrode)
First, LiCoO ₂ powder, graphite powder, and polyvinylidene fluoride powder were mixed at a mass ratio of 90: 7: 3, and N-methylpyrrolidone and ethanol were added as solvents to knead the mixture. A positive electrode paste was prepared.
Next, the obtained positive electrode paste was uniformly coated on an aluminum foil having a thickness of 15 μm. The aluminum foil coated with the positive electrode paste was dried in a nitrogen atmosphere to volatilize the solvent, and then rolled to produce a sheet having an overall thickness of 150 μm. This sheet was cut into a width of 43 mm and a length of 285 mm, and then a lead terminal of an aluminum foil was attached to one end thereof by ultrasonic welding to serve as a positive electrode.

(Manufacturing of negative electrode and evaluation of productivity)
The copper foil used for the negative electrode current collector is a normal copper foil produced in the production examples and comparative production examples.
First, the copper foil was cut into a strip shape so that the width dimension was 720 mm (the width direction of the strip shape was parallel to the width direction of the copper foil).
Next, a natural graphite powder (average particle diameter: 10 μm) and polyvinylidene fluoride powder are mixed at a mass ratio of 90:10, and N-methylpyrrolidone and ethanol are added as solvents and kneaded. To prepare a negative electrode paste.
Next, on the strip-shaped copper foil, the obtained negative electrode paste was applied on both sides of the copper foil in a double stripe shape with a width of 300 mm on both sides. The copper foil coated with the negative electrode paste was dried in a nitrogen atmosphere to volatilize the solvent, and then rolled to form a total thickness of 150 μm by compression. After that, the coating portion was cut into a width of 43 mm and a length of 280 mm. As a negative electrode, a lead terminal having a nickel foil attached to one end thereof was welded by ultrasonic welding.
Finally, the presence or absence of wrinkles on the copper foil and the presence of burrs on the cut portion were visually confirmed, and evaluated as battery productivity. The case where no wrinkles or cracks occurred on the copper foil was evaluated as "excellent (◎)", and the case where any slight wrinkles or burrs occurred on the copper foil, but there was no problem in practical terms was evaluated as "good (○)", resulting in At least one of wrinkles and burrs was evaluated as "poor (×)" when it was expected to affect subsequent battery characteristics evaluation.

(Battery production and evaluation of battery characteristics)
A 25 μm-thick polypropylene separator was sandwiched between the manufactured positive electrode and the negative electrode, and the whole was wound. The separator was stored in a nickel-plated battery can with a mild steel surface, and the lead terminals of the negative electrode were spot-welded to the bottom of the can. . Next, the upper cover of the insulating material is placed, and a gasket is inserted. Then, the lead terminal of the positive electrode is ultrasonically welded with an aluminum safety valve for connection, and propylene carbonate, diethyl carbonate, and ethyl carbonate are connected. The formed non-aqueous electrolyte is poured into a battery can. Thereafter, a cover was attached to the safety valve to assemble a closed-structure lithium-ion secondary battery having an outer shape of 14 mm and a height of 50 mm.
The cycle of charging the assembled battery at a charging current of 100 mA to 4.2 V and discharging at a discharge current of 100 mA to 2.4 V was calculated as 1 cycle, and a charge-discharge cycle test was performed. The number of cycles when the discharge capacity of the battery dropped to 800 mAh was taken as the cycle life (cycle characteristics), and the battery characteristics were evaluated. The results are shown in Table 2.
A cycle life of 500 times or more was evaluated as "excellent (◎)", 300 times or more and less than 500 times were evaluated as "good (○)", and less than 300 times were evaluated as "bad (x)". A copper foil evaluated as "defective (×)" indicates a copper foil unsuitable for this application. "Good (○)" indicates a suitable copper foil, and "Excellent (◎)" indicates a copper foil with better battery characteristics.

(Overview)
Comprehensive evaluation was performed based on the following evaluation criteria. In addition, in this embodiment, A and B are used as the pass grade in the comprehensive evaluation.
A (Excellent): Both the above productivity and battery characteristics were evaluated as "Excellent (◎)".
B (Pass): There was no "defective (×)" in the evaluation of both the productivity and the battery characteristics, and at least one of the productivity and the battery characteristics was evaluated as "good (○)".
C (Failure): At least one of the above-mentioned productivity and battery characteristics was evaluated as "defective (×)".

(Table 2)
Note: The bold underline in the table indicates that it is out of the proper range of the present invention, and the evaluation result does not reach the pass grade in this example.

As shown in Table 2, the copper foils produced in Production Examples 1 to 9 had a predetermined tensile strength under normal conditions. At this time, the unevenness of the tensile strength in the width direction of the strip was small. High tensile strength can also be maintained in the later state (Examples 1 to 9). It was confirmed that such copper foils of Examples 1 to 9 are excellent in both productivity in the production of a lithium ion secondary battery and battery characteristics as a lithium ion secondary battery.

In contrast, the copper foil produced in Comparative Production Example 1 had too high tensile strength in the normal state and poor elongation (Comparative Example 1). In addition, the copper foil of Comparative Production Example 2 had low tensile strength in the normal state and the state after the heat treatment (Comparative Example 2). Therefore, such electrolytic copper foils of Comparative Examples 1 and 2 were found to have poor battery characteristics as lithium ion secondary batteries.

Moreover, the copper foils produced in Comparative Manufacturing Examples 3 to 6 had uneven tensile strength in the width direction in a normal state (Comparative Examples 3 to 6). Therefore, such copper foils of Comparative Examples 3 to 6 were found to be inferior in productivity when producing lithium ion secondary batteries.

(Examples 11 to 19 and Comparative Examples 13, 15 and 16)
(Evaluation of printed circuit board applications)
Using the copper foils produced in the above Production Examples 1 to 10 and Comparative Production Examples 3, 5, and 6 as a copper foil base material, one surface of each copper foil was subjected to roughening treatment and surface treatment under the conditions shown below to obtain Surface treated copper foil (thickness: 12μm).
About the obtained surface-treated copper foil, the characteristic evaluation shown below was performed. The evaluation conditions of each characteristic are as follows. Unless otherwise specified, each measurement is performed at room temperature. The results are shown in Table 3.

(Formation of roughened layer)
First, the copper foil used for a copper foil base material was the normal copper foil (width direction dimension 1100 mm) produced by said manufacturing example 1-10 and comparative manufacturing examples 3, 5, and 6.
Next, the surfaces shown in Table 3 of the copper foil substrate were subjected to the following roughening plating treatment 1 and roughening plating treatment 2 in order to form a roughening treatment layer.

Rough plating treatment 1
Copper sulfate: 21g / L based on copper concentration
Sulfuric acid: 97g / L
Cobalt (II) sulfate heptahydrate: 3.6g / L based on cobalt concentration
Liquid temperature: 36 ℃
Current density: 32A / dm ²
Time: 1 ～ 30 seconds

Rough plating treatment 2
Copper sulfate: 50g / L based on copper concentration
Sulfuric acid: 120g / L
Liquid temperature: 62 ℃
Current density: 10A / dm ²
Time: 1 ～ 30 seconds

(Formation of surface treatment layer)
Next, on the roughened surface of the copper foil on which the roughened layer was formed, a nickel layer, a zinc layer, a chromate-treated layer, and a silane coupling agent layer described below were sequentially formed.

Formation of nickel layer (base layer) The roughened surface of the copper foil on which the roughened layer was formed was electroplated under the Ni plating conditions shown below to form a nickel layer (the adhesion amount of Ni was 0.23 mg / dm ² ). The plating solution for nickel plating contains nickel sulfate, ammonium persulfate ((NH ₄ ) ₂ S ₂ O ₈ ), boric acid (H ₃ BO ₃ ), nickel concentration is 5.3 g / L, and ammonium persulfate concentration is 28.0 g / L, boric acid concentration was 19.5 g / L. The temperature of the plating solution was 23.5 ° C, the pH was 3.9, the current density was 2.6 A / dm ² , and the plating treatment time was 1 to 30 seconds.

Formation of Zinc Layer (Heat-Resistant Layer) Furthermore, a zinc layer was formed by performing electroplating on a nickel layer under the Zn plating conditions shown below (the Zn adhesion amount was 0.05 mg / dm ² ). The plating solution used for zinc plating contains zinc sulfate heptahydrate, sodium hydroxide, a zinc concentration of 10 g / L, and a sodium hydroxide concentration of 29 g / L. The temperature of the plating solution was 30 ° C, the current density was 5 A / dm ² , and the plating treatment time was 1 to 30 seconds.

Formation of chromate-treated layer (rust-proof treatment layer) Furthermore, electroplating was performed on the zinc layer under the Cr plating conditions shown below to form a chromate-treated layer (Cr adhesion amount 0.05mg / dm ² ). The plating solution used for chromium plating contains chromic anhydride (CrO ₃ ), and the chromium concentration is 3.1 g / L. The temperature of the plating solution was 20 ° C, the pH was 2.1, the current density was 0.6 A / dm ² , and the plating treatment time was 1 to 30 seconds.

Formation of Silane Coupling Agent Layer Further, the following treatment was performed to form a silane coupling agent layer on the chromate-treated layer. That is, methanol or ethanol was added to the silane coupling agent aqueous solution, and it adjusted to predetermined pH, and obtained the processing liquid. This treatment liquid was applied to a chromate-treated layer of a surface-treated copper foil, and after being kept for a predetermined time, dried with warm air to form a silane coupling agent layer. As the silane coupling agent, 3-mercaptopropyltrimethoxysilane (KBM-803, manufactured by Shin-Etsu Chemical Industry Co., Ltd.) was used, and an aqueous silane coupling agent solution was prepared at a concentration of 1.0% and a pH of 4.0.

<Developed area ratio of roughened surface (Sdr)>
The roughened surface of the surface-treated copper foil obtained as described above was subjected to measurement of a developed area ratio (Sdr). The measurement was performed in the same manner as the measurement of the above-mentioned cut copper foil. The results are shown in Table 3.

(Production of copper clad laminates and evaluation of pressurization failure)
The surface-treated copper foil obtained above was cut into a size of 200 mm × 200 mm, and the roughened surface of the surface-treated copper foil was superimposed on a FR4-based resin substrate (EI-6765, manufactured by Sumitomo Bakelite Co., Ltd.). It was heated for 1 hour under the conditions of 170 ° C. and a surface pressure of 1.5 MPa to make a copper clad laminate. Thirty copper-clad laminates were produced by this method, and the presence or absence of wrinkles was visually confirmed.
The copper-clad laminated board in which wrinkles were confirmed was counted as one wrinkle defect. In addition, in the evaluation of the wrinkle defect, the case where the number of wrinkle defects is 0 to 1 is evaluated as "excellent (◎)", and when the number of the wrinkle defects is 2 to 4, it is evaluated as "good (○)" A case where the number of wrinkle defects was 5 or more was evaluated as "defective (×)". Table 3 shows the number of wrinkle defects and the evaluation results.

(Evaluation of etching factor)
The surface-treated copper foil obtained above was cut into a size of 200 mm × 200 mm, and a photoresist pattern having an L & S of 30/30 μm was formed on the roughened surface of the surface-treated copper foil by a subtractive method. Then, etching is performed to form a wiring pattern. A dry resist film was used as the photoresist, and a mixed solution containing copper chloride and hydrochloric acid was used as the etching solution. Then, the etching factor (Ef) of the obtained wiring pattern was measured. The etching factor is when the foil thickness (μm) of the copper foil is set to H, the bottom width (μm) of the formed wiring pattern is set to B, and the top width (μm) of the formed wiring pattern is set to T. The represented value. The thickness H of the copper foil is used as the thickness of the surface-treated copper foil. In addition, when the dimensions of the bottom width B and the top width T are changed to a just-etching position (the position of the photoresist end portion coincides with the position of the bottom of the wiring pattern), the wiring pattern is measured using a microscope.
Ef = 2H / (B-T)
In the evaluation of the etching factor, the case where the Ef value is 3.5 or more is evaluated as "Excellent (◎)", and the case where the Ef value is 2.6 or more and less than 3.5 is evaluated as "Good (○)", and the Ef value When it is less than 2.6, it is evaluated as "bad (×)". The Ef values and evaluation results are shown in Table 3.
In addition, when the value of Ef is small, the sidewall of the wiring pattern loses its verticality. When a fine wiring pattern with a narrow line width is formed, slag of copper foil is generated between adjacent wiring patterns and there is a short Danger of connecting or disconnecting.

(Evaluation of adhesion)
The surface-treated copper foil obtained above was cut into a size of 200 mm × 200 mm, and the roughened surface of the surface-treated copper foil was superimposed on a FR4-based resin substrate (same as above) at 170 ° C. and a surface pressure of 1.5 MPa. It was heated and pressed under the conditions for 2 hours to produce a copper-clad laminated board.
Using the produced copper-clad laminated board as a measurement sample, the copper foil was etched to form a circuit wiring having a width of 1 mm, and a test piece was prepared. Next, the resin substrate side of the test piece was fixed to a stainless steel plate with a double-sided tape, and the circuit wiring portion (copper foil portion) was stretched and peeled at a speed of 50 mm / min in a 90-degree direction, and the peel strength at the time of peeling was measured ( kN / m). The peel strength was measured using a TENSILON universal material testing machine (manufactured by A & D Corporation).
In the evaluation of adhesion, the case where the peel strength (kN / m) was 0.6 kN / m or more was evaluated as "good (○)", and the case where the peel strength (kN / m) was less than 0.6 kN / m was evaluated as "Bad (×)". The evaluation results are shown in Table 3.

(Overview)
Comprehensive evaluation was performed based on the following evaluation criteria. In addition, in this embodiment, A and B in the comprehensive evaluation are taken as a pass grade.
A (excellent): Both the above-mentioned wrinkle failure and the etching factor were evaluated as "excellent (◎)" and the adhesion was "good (○)".
B (Pass): None of the above-mentioned wrinkle defects, etching factors, and adhesion evaluation was "bad (×)", and at least one of the wrinkle defects and etching factors was evaluated as "good (○)".
C (Failure): At least one of the above-mentioned wrinkle failure, etching factor, and adhesion was evaluated as "defective (×)".

In addition, the dispersion σ ² of the tensile strength (Ts) of the copper foil substrate shown in Table 3 under normal conditions is the same as the dispersion σ ² of the tensile strength (Ts) of the electrolytic copper foil shown in Table 2 under normal conditions. data of.

(table 3)
Note: The bold underline in the table indicates that it is out of the proper range of the present invention, and the evaluation result does not reach the pass grade in this example.

As shown in Table 3, the copper foils of Examples 1 to 9 produced in Production Examples 1 to 9 had particularly small tensile strength unevenness in the width direction of the strip. When a copper-clad laminated board was produced using the copper foils of Examples 1 to 9, it was confirmed that the occurrence of wrinkles due to pressure during production was effectively suppressed (Examples 11 to 19).

In addition, it was confirmed that the surface of the copper foils of Examples 1 to 9 was subjected to surface treatment so that the developed surface area ratio (Sdr) of the roughened surface was within a predetermined range, so that good adhesion and a large etching factor could be obtained. Printed circuit board (Examples 11 to 19).

In contrast, the copper foils of Comparative Examples 3, 5, and 6 produced in Comparative Manufacturing Examples 3, 5, and 6 had uneven tensile strength in the width direction in the normal state. Therefore, when the copper-clad laminated sheet was produced using the copper foils of Comparative Examples 3, 5, and 6 as described above, it was confirmed that wrinkles were generated due to pressure (Comparative Examples 13, 15 and 16).

1‧‧‧ manufacturing equipment

11‧‧‧ cathode drum

11a‧‧‧Drum rotation direction

12‧‧‧PR pulse electrode

13‧‧‧Anode

14‧‧‧Bath

20‧‧‧ Electrolyte

20a‧‧‧ Electrolyte supply direction

30‧‧‧ Copper foil

30a‧‧‧ peeling direction

FIG. 1 is an example of a manufacturing apparatus for manufacturing the electrolytic copper foil of the present invention.

Claims (11)

An electrolytic copper foil is obtained by cutting the electrolytic copper foil from one end in the width direction to the other end at intervals of 100 mm. At this time, the tensile strength measured by using each of the cut copper foils meets the following requirements (I) to (III): Element (I): The average value of the tensile strength of the cut copper foil in the normal state is 400 MPa to 650 MPa; Element (II): The element of the tensile strength of the cut copper foil in the normal state. The dispersion σ ² is 18 [MPa] ² or less; and requirement (III): the average value of the tensile strength of each cut copper foil in the state after heat treatment at 150 ° C. for 1 hour is 350 MPa or more. For example, the electrolytic copper foil in item 1 of the request has a width dimension of 600 mm or more. For example, the electrolytic copper foil according to item 1 or 2 of the claim, wherein the average value of the elongation of the cut copper foil in the normal state is 5.3% or more. For example, the electrolytic copper foil of any one of claims 1 to 3 has an electrical conductivity of 88% IACS or more. For example, the electrolytic copper foil of any one of claims 1 to 4 has a developed area ratio (Sdr) of the glossy surface of 12% to 27%. The electrolytic copper foil according to any one of claims 1 to 5 is used as a negative electrode current collector of a lithium ion secondary battery. A negative electrode for a lithium ion secondary battery using the electrolytic copper foil according to claim 6. A lithium ion secondary battery using the negative electrode for a lithium ion secondary battery according to claim 7. An electrolytic copper foil having a roughened surface on at least one side of the electrolytic copper foil according to any one of claims 1 to 5, and the developed area ratio (Sdr) of the roughened surface is 20% to 200%. A copper-clad laminated board includes the electrolytic copper foil according to claim 9 and a resin substrate laminated on a roughened surface of the electrolytic copper foil. A printed circuit board provided with a copper-clad laminated board according to claim 10.