KR20200121287A - Electrolytic copper foil, and negative electrode for lithium ion secondary battery, lithium ion secondary battery, copper clad laminated board and printed wiring board using the electrolytic copper foil - Google Patents

Abstract

The tensile strength measured using each cut copper foil obtained by cutting the electrolytic copper foil from one end in the width direction to the other at 100 mm intervals satisfies the following requirements (I) to (III). -Requirement (I): The average value of the tensile strength of each of the cut copper foils in the normal state is 400 MPa or more and 650 MPa or less. -Requirement (II): The dispersion σ ² of the tensile strength of each of the cut copper foils in a normal state is 18 [MPa] ² or less. -Requirement (III): The average value of the tensile strength of each of the cut copper foils in a state after being heat-treated at 150°C for 1 hour is 350 MPa or more.

Description

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

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

Lithium ion secondary batteries (hereinafter, simply referred to as "batteries" in some cases) are composed of, for example, a positive electrode, a negative electrode, and a non-aqueous electrolyte, and are mainly used for mobile phones and notebook PCs. In addition, in recent years, the demand for automobile applications is also rapidly increasing.

The negative electrode of a lithium ion secondary battery is formed by forming a negative electrode active material layer on the surface of a negative electrode current collector, and copper foil is generally used for the negative electrode current collector. In particular, compared to rolled copper foil, electrolytic copper foil (hereinafter, simply referred to as ``copper foil'' in some cases) is widely used, which makes it easier to achieve both conductivity and strength, and can be thinned at low cost. .

The negative electrode of such a lithium ion secondary battery using copper foil is formed by applying carbon particles or the like as a negative electrode active material layer to the surface of the copper foil, drying, and pressing.

BACKGROUND ART In recent years, as the market expands, lithium ion secondary batteries are required to improve battery characteristics and improve productivity more than ever before. In response to these demands, for example, increasing the thickness of the active material layer and increasing the press pressure are being made to increase the capacity of the battery, and increase the width of copper foil and increase the number of stripe coatings of the active material layer to improve productivity. The back is being done. In addition, in the lithium ion secondary battery, weight reduction of the battery is also desired, and thinning of the copper foil is also progressing.

However, under the manufacturing conditions corresponding to various demands as described above, wrinkles or cracks in the copper foil, defects in shape of the slit cross section, etc., are liable to occur during coating, pressing, sliting, etc. of the active material layer, resulting in decreased productivity of the battery. There was a case that caused it.

In addition, during charging and discharging of the lithium ion secondary battery, the active material layer expands and contracts, and the stress thereof may be applied to other members such as copper foil or separator. Such a load of stress may cause a short circuit or ignition due to the destruction of other members such as a separator. In addition, the stress load on the copper foil not only causes the active material layer to peel from the copper foil, but also causes destruction such as wrinkles or fractures in the copper foil, and also causes a decrease in battery life. Usually, the stress applied to the copper foil becomes larger with an increase in the thickness or density of the active material layer.

In response to various problems as described above, in the prior art, the mechanical properties of the copper foil are improved, such as increasing the tensile strength of the copper foil to a predetermined value or more, or increasing the elongation of the copper foil to a predetermined value or more and reducing the elongation anisotropy. A method of making it possible has been proposed (refer to Patent Documents 1 to 4).

However, in actual battery production, as in Patent Document 1, simply improving the mechanical properties such as tensile strength and elongation of the copper foil cannot sufficiently solve the above problems. In addition, as in Patent Documents 2 and 3, the crystal grain size and orientation are controlled, or as in Patent Document 4, the 10-point average roughness (Rzjis), which includes only information in the height direction for the two-dimensional cross-sectional shape of the surface, is controlled. And, simply reducing the stretch anisotropy was insufficient to reduce the intensity unevenness due to the location of the wide copper foil. In particular, in recent years, the case of applying a plurality of active material layers to a wide copper foil (for example, 600 mm or more) is increasing, and when stripe coating a plurality of active material layers on such a wide copper foil, the thickness of the active material layer The higher the density, the greater the load applied to the copper foil tends to be.

In addition, recently, using a copper foil having a roughened surface, an adhesive resin such as an epoxy resin was previously adhered to the roughened surface of the copper foil, and the adhesive resin was semi-cured (B stage). A printed wiring board (especially a build-up wiring board) is manufactured by thermocompressing a copper foil and an insulating board with the side of the said insulating resin layer as the insulating board side, and the side of the said insulating resin layer.

In the manufacture of such a printed wiring board, there is a problem in that the copper foil is wrinkled due to pressing when the copper foil and the insulating substrate are thermally compressed.

Therefore, also in the use of a printed wiring board, development of a copper foil in which wrinkles are less likely to occur during manufacturing has been demanded.

Japanese Patent No. 55588607 Japanese Patent No. 5074611 Japanese Patent No. 5718476 Japanese Patent No. 6218233

Therefore, the present invention has high mechanical strength and heat resistance, and the productivity of a battery in which wrinkles, fractures, and shape defects of the slit cross-section do not occur even if a plurality of stripe coatings are applied at the time of manufacturing a battery even if it is wide (hereinafter, simply `` It is an object of the present invention to provide an electrolytic copper foil having excellent battery productivity"), and a negative electrode for a lithium ion secondary battery and a lithium ion secondary battery using the electrolytic copper foil. Further, an object of the present invention is to provide an electrolytic copper foil in which wrinkles are less likely to occur due to pressing during manufacturing, and a copper clad laminate and a printed wiring board using the electrolytic copper foil, even when used as a printed wiring board application.

The present inventors, as a result of intensive examination, showed that the tensile strength measured using each cut copper foil obtained by cutting an electrolytic copper foil at intervals of 100 mm from one end to the other in the width direction thereof was determined by predetermined requirements (I) to ( By satisfying III), it was found that an electrolytic copper foil having high mechanical strength and heat resistance and excellent in battery productivity even in a wide width can be obtained, thereby completing the present invention. Further, it was found that even when the electrolytic copper foil described above is used for a printed wiring board, wrinkles are less likely to occur during pressing.

That is, the summary structure of this invention is as follows.

[1] The tensile strength measured using each cut copper foil obtained by cutting an electrolytic copper foil at intervals of 100 mm from one end in the width direction thereof to the other end meets the following requirements (I) to (III). Copper foil.

-Requirement (I): The average value of the tensile strength of each of the cut copper foils in the normal state is 400 MPa or more and 650 MPa or less.

-Requirement (II): The dispersion σ ² of the tensile strength of each of the cut copper foils in a normal state is 18 [MPa] ² or less.

-Requirement (III): The average value of the tensile strength of each of the cut copper foils in a state after being heat-treated at 150°C for 1 hour is 350 MPa or more.

[2] The electrolytic copper foil according to [1], wherein the dimension in the width direction is 600 mm or more.

[3] The electrolytic copper foil according to [1] or [2], wherein the average value of elongation in the normal state of each cut copper foil is 5.3% or more.

[4] The electrolytic copper foil according to any one of [1] to [3], having a conductivity of 88% IACS or more.

[5] The electrolytic copper foil according to any one of [1] to [4], wherein the spread 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 [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 according to [6] above.

[8] A lithium ion secondary battery using the negative electrode for lithium ion secondary batteries according to [7] above.

[9] has a roughened surface on at least one surface of the electrolytic copper foil according to any one of [1] to [5],

The electrolytic copper foil in which the developed area ratio (Sdr) of the roughened surface is 20% or more and 200% or less.

[10] A copper clad laminate comprising the electrolytic copper foil according to the above [9] and a resin substrate laminated on the roughened surface of the electrolytic copper foil.

[11] A printed wiring board comprising the copper clad laminate according to [10].

ADVANTAGE OF THE INVENTION According to this invention, it has high mechanical strength and heat resistance, and can provide an electrolytic copper foil excellent in battery productivity even in a wide width, and a negative electrode for a lithium ion secondary battery and a lithium ion secondary battery using the electrolytic copper foil. Further, according to the present invention, even when used as a printed wiring board application, it is possible to provide an electrolytic copper foil in which wrinkles are unlikely to occur due to pressing during manufacturing, a copper clad laminate using the electrolytic copper foil, and a printed wiring board.

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

(Form for carrying out the invention)

An embodiment of the electrolytic copper foil according to the present invention will be described in detail below.

In the electrolytic copper foil of the present invention, the tensile strength measured using each cut copper foil obtained by cutting at intervals of 100 mm from one end in the width direction to the other end satisfies the following requirements (I) to (III). It is characterized.

-Requirement (I): The average value of the tensile strength of each of the cut copper foils in the normal state is 400 MPa or more and 650 MPa or less.

-Requirement (II): The dispersion σ ² of the tensile strength of each of the cut copper foils in a normal state is 18 [MPa] ² or less.

-Requirement (III): The average value of the tensile strength of each of the cut copper foils in a state 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 copper foil produced by electrolytic treatment, untreated copper foil which has not been subjected to surface treatment after foiling, and copper foil subjected to surface treatment as necessary (surface treatment electrolytic copper foil It means to include any of ). Moreover, the thickness of the electrolytic copper foil becomes like this. Preferably it is 30 micrometers or less, More preferably, it is 4-15 micrometers. In addition, below, unless specifically stated, "copper foil" means "electrolytic copper foil".

In addition, the "width direction" of the copper foil is a direction perpendicular to the conveying direction (same as the peeling direction from the cathode electrode) during the manufacture of the copper foil, and in the case of a copper foil wound in a roll shape, its longitudinal direction is conveyed. Corresponds to the direction. In addition, the "width direction dimension" is a dimension from one end of the copper foil in the width direction to the other end.

In addition, "cut copper foil" is a copper foil obtained by cutting a copper foil from one end in the width direction to the other at 100 mm intervals. Here, the cut copper foil used to evaluate the characteristics of the copper foil is all of the cut copper foil having a width direction dimension of 100 mm (±5 mm), and a cut copper foil whose width direction dimension is less than 95 mm is not a measurement object. . For example, in the case of a copper foil with a dimension of 850 mm in the width direction, if cut at 100 mm intervals from one end in the width direction to the other end, 9 cut copper foils are obtained, but the measurement object is the width It is 8 pieces of cut copper foil with a direction dimension of 100㎜ (±5㎜).

In addition, the "normal state" means that the copper foil is in a state of unheated as it was manufactured, and does not have a heat history accompanying heating above 60°C, for example, at room temperature (15 to 30°C). , Also in the following), it indicates the state as it was placed. In addition, "the state after being heat-treated at 150°C for 1 hour" refers to a state after the copper foil is heat-treated at 150°C for 1 hour and cooled to room temperature, for example.

In the conventional high-strength copper foil, when applying a plurality of stripes on a wide copper foil, there is a problem that wrinkles, fractures, shape defects of the slit cross section, and the like tend to occur. Regarding this problem, the present inventors have conducted extensive research and found that the occurrence of the above problem is related to the degree of variation in tensile strength in the width direction of the copper foil.

In general, in stripe coating, a portion where an active material layer is applied and a portion not coated with the active material layer are alternately formed in the width direction of the copper foil, and a portion applied with a load in the width direction of the copper foil and a portion that is not are alternately present. When performing press or slit treatment in the production line for copper foil after such stripe coating, if there is unevenness in tensile strength in the width direction of the copper foil, there is a rattle on the line conveyance, slip in the width direction of the copper foil, tension fluctuation, etc. It turned out that this tends to occur. In particular, rattles on line conveyance or slip in the width direction of the copper foil cause wrinkles or fractures, and fluctuations in tension cause abnormalities in the cross section of wrinkles or slits (burr or loosening, etc.). I could see that.

Based on the above recognition, in the present invention, in the copper foil having high strength and excellent heat resistance, in particular, by reducing the variation in tensile strength in the width direction of the copper foil as compared to the conventional high strength copper foil, the above It has been found that the same problem can be solved and productivity can be improved in the mass production process of a battery.

Further, the inventors of the present invention intensively investigated the defects in the pressing process of the printed wiring board, and found that the larger the nonuniformity in the tensile strength of the copper foil, the more wrinkles occurred.

Based on the above recognition, it was found that even for the copper foil used for a printed wiring board, by reducing the unevenness of the tensile strength in the width direction as described above, wrinkle defects can be suppressed and productivity of the printed wiring board can be improved.

The width direction dimension of the copper foil of the present invention is preferably 300 mm or more, more preferably 600 mm or more, still more preferably 900 mm or more, and even more preferably 1200 mm or more. Such copper foil is suitable when used for mass production manufacturing of a battery or a printed wiring board. Moreover, although the upper limit of the width direction dimension of a copper foil depends on the manufacturing equipment of a copper foil, it is 2000 mm, for example, and it is preferable that the width direction dimension of a copper foil is 1500 mm or less from a viewpoint of reducing the characteristic variation in the width direction.

The larger the dimension in the width direction of the copper foil is, the more suitable it is in that a battery or a printed wiring board can be mass-produced, but the stress applied at the time of manufacturing a battery or a printed wiring board tends to have a different configuration in the width direction of the copper foil. Therefore, in particular, with the wide copper foil, the above-described problem becomes remarkable, but in the present invention, the aforementioned problem can be solved by reducing the variation in tensile strength in the width direction of the copper foil.

In the present invention, in order to properly evaluate the non-uniformity of characteristics in the width direction of the copper foil, in particular, each cut copper foil obtained by cutting the copper foil at intervals of 100 mm from one end to the other in the width direction is used. It is measured and finally evaluated as a whole of the copper foil. Hereinafter, it demonstrates in detail for each requirement.

<Requirement (Ⅰ)>

In the copper foil of the present invention, the average value of the tensile strength (Ts) of each cut copper foil in a normal state is 400 MPa or more and 650 MPa or less, preferably 400 MPa or more and 600 MPa or less, and more preferably 445 MPa or more. It is 600 MPa or less, More preferably, it is 450 MPa or more and 600 MPa or less. By setting it as 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 in a normal state is less than 400 MPa, it is not able to withstand the effect of an increase in the load caused by the electrode material accompanying the high capacity of the battery, and there is a tendency that the copper foil is wrinkled. . Moreover, when the average value of the tensile strength of each cut copper foil in a normal state exceeds 650 MPa, the elongation of a copper foil falls, and there exists a tendency for foil breakage of a copper foil to occur.

Further, even when used for a printed wiring board, when the tensile strength in the normal state of the copper foil is less than 400 MPa, wrinkles occur during transportation of the thin foil sheet product, resulting in deterioration in handling properties. In addition, when the tensile strength of the copper foil in the normal state exceeds 650 MPa, breakage of the foil tends to occur during precipitation production with a drum, and productivity deteriorates.

<Requirement (Ⅱ)>

In the copper foil of the present invention, dispersion σ ² of the tensile strength (Ts) of each cut copper foil in a normal state is 18 [MPa] ² or less, preferably 14 [MPa] ² or less, and more preferably 11 It is [MPa] ² or less, More preferably, it is 10 [MPa] ² or less. Here, the dispersion σ ² of the tensile strength of each cut copper foil is an index of the non-uniformity of the tensile strength in the width direction of the copper foil, and the larger the value, the greater the non-uniformity of the tensile strength. In the copper foil of the present invention, when the dispersion σ ² of the tensile strength of each cut copper foil in a normal state is within the above range, it is possible to effectively prevent the occurrence of local wrinkles and slack in the electrode manufacturing process. Moreover, also in the manufacturing process of a printed wiring board, generation|occurrence|production of wrinkles by a press can be effectively prevented. On the other hand, when the dispersion σ ² of the tensile strength of each cut copper foil in the normal state exceeds 18 [MPa] ² , the unevenness of the tensile strength in the width direction of the copper foil is large, and the copper foil is loaded in the electrode manufacturing process. Since the stress is non-uniform in the width direction of the copper foil, local wrinkles or looseness occur, and there is a tendency that the productivity of the battery decreases. Further, also in the manufacturing process of the printed wiring board, there is a tendency that the occurrence of wrinkles due to pressing becomes remarkable. 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 cut copper foil in a state after being heat-treated at 150°C for 1 hour is 350 MPa or more, preferably 380 MPa or more, and more preferably 400 MPa or more. to be. By setting it as the above range, sufficient strength can be maintained at the time of processing into a battery, durability to a load during charging and discharging of the battery is excellent, and the cycle life of the battery is improved. On the other hand, if the average value of the tensile strength of each cut copper foil in the state after being heat-treated at 150°C for 1 hour is less than 350 MPa, the strength decreases during processing into a battery, and does not withstand the load during charging and discharging of the battery. The copper foil is not easily broken, which tends to lead to a decrease in the cycle life of the battery. In addition, the upper limit of the average value of the tensile strength of each cut copper foil in a state after heat treatment at 150°C for 1 hour is, for example, 550 MPa, preferably 450 MPa from the viewpoint of having an appropriate elongation even after heating. .

In addition, in the manufacture of a printed wiring board, when the average value of the tensile strength of each cut copper foil in a state after being heat-treated at 150°C for 1 hour is 350 MPa or more, the crystal grains are finely formed even after heating in the lamination process of the substrate. Since it is maintained, the etching property becomes good. On the other hand, when the average value of the tensile strength is less than 350 MPa, the crystal grains tend to increase after heating in the lamination process of the substrate, and since the copper particles are hardly melted by etching, the etching property is deteriorated.

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

<Height (El)>

In the copper foil of the present invention, the average value of the elongation (El) in the normal state of each cut copper foil is preferably 5.3% or more, more preferably 6.0% or more, still more preferably 7.5% or more, even more preferably It is 9.0% or more. By setting it as the above range, the durability against the stress applied to the copper foil during charging and discharging of the battery is improved. In addition, the upper limit of the average value of elongation in the normal state of each cut copper foil is, for example, 13.0% from the viewpoint of high strength, and preferably 11.0%.

In addition, the average value of the elongation of each cut copper foil in a state after being heat-treated at 150°C for 1 hour is preferably in the same range as in the case of the normal state.

In addition, elongation is a value measured under the evaluation conditions described in this example.

<Expanded area ratio (Sdr)>

Conventionally, as a parameter representing the surface shape of copper foil, it was common to use 10-point average roughness Rzjis, but in 10-point average roughness Rzjis, only information in the height direction for the two-dimensional cross-sectional shape of the surface was included, so correct evaluation was performed. I couldn't do it. On the other hand, since the development area ratio Sdr contains three-dimensional information of the surface, more appropriate characteristic evaluation becomes possible.

The development area ratio (Sdr) refers to the ratio of the area added by the surface properties based on the ideal surface having the size of the measurement area, and 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 coordinate of a certain point, and by differentiating this, it becomes the inclination at the coordinate point. In addition, A is the planar area of a measurement area.

In addition, the development area ratio (Sdr) can be obtained by measuring and evaluating the unevenness difference on the copper foil surface by, for example, a three-dimensional white interference microscope, a scanning electron microscope (SEM), an electron beam three-dimensional roughness analyzer, etc. . In general, the development area ratio Sdr is not related to the change in the surface roughness Sa, and tends to increase as the spatial complexity of the surface properties increases.

In the copper foil of the present invention, the developed area ratio (Sdr) of the glossy surface is preferably 27% or less, more preferably 20% or less, still more preferably 18.5% or less, and even more preferably 17% or less. to be. By setting it as the said range, the nonuniformity of the strength of the width direction of a copper foil can be further reduced, and the productivity of a battery further improves. Moreover, by setting it as the said range, generation|occurrence|production of wrinkles by a press is suppressed also in the manufacturing process of a printed wiring board. In addition, the lower limit of the development 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 has a roughened surface area ratio (Sdr) of preferably 92% or less, more preferably 90% or less, further preferably 80% or less, and even more preferably It is 70% or less. By setting it as the above range, since the coating of the active material layer is uniformly performed during electrode manufacturing, a stress load to the copper foil is uniformly generated, so that wrinkles and looseness are reduced, and productivity is improved. Moreover, by setting it as the said range, generation|occurrence|production of wrinkles by a press is suppressed also in the manufacturing process of a printed wiring board. In addition, the lower limit of the development area ratio Sdr of the rough surface may be, for example, 62%.

Here, the development 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 referred to as the ``S (shiny) surface'') refers to the surface on the side that was in contact with the cathode drum when the electrolytic copper foil was removed, and the rough surface (also referred to as the ``M (matt) surface'') Yes) means the side opposite to the glossy side. In addition, in the present specification, when referred to as a glossy surface and a rough surface, it refers to an untreated copper foil surface that has not been subjected to surface treatment after thinning, and is distinguished from a roughened surface that has been subjected to a roughening treatment on the glossy surface and the rough surface. It should be done.

The copper foil of the present invention may have a roughened surface on at least one surface of the copper foil, and the development area ratio (Sdr) of the roughened surface is preferably 20% or more and 200% or less, more preferably 25 It is not less than% and not more than 197%. Such copper foil is particularly suitable for use as a printed wiring board. For example, if the development area ratio (Sdr) of the roughened surface is less than 20%, the adhesion when adhering the adhesive resin to the surface tends to decrease, and if it exceeds 200%, the etching factor decreases. In some cases, formation of fine wiring becomes difficult.

The development area ratio (Sdr) of the roughened surface is taken as a value measured under the evaluation conditions described in this example.

<Conductivity>

The copper foil of the present invention has a conductivity of preferably 88% IACS or more, more preferably 90% IACS or more, still more preferably 91% IACS or more, and even more preferably 92% IACS or more. By setting it as the said range, when manufacturing a battery, the internal resistance of a negative electrode falls, and the cycle characteristic of a battery improves. Moreover, if it is the said range, it is suitable also when using copper foil as a printed wiring board.

Here, the electrical conductivity is a value measured under the evaluation conditions described in this example.

<Method of manufacturing electrolytic copper foil>

Next, a preferable manufacturing method of the electrolytic copper foil of the present invention will be described.

In the electrolytic copper foil of the present invention, for example, an electrolyte is supplied between an insoluble anode made of titanium coated with a platinum group element or an oxide element thereof, and a cathode drum made of titanium formed facing the anode, and the cathode drum is at a constant speed. It can be manufactured by a method in which copper is deposited on the surface of the cathode drum by passing a direct current between the anodes while rotating at, and the deposited copper is peeled off the surface of the cathode drum and continuously wound. Further, an apparatus for performing such manufacturing 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 can be suitably used.

In addition, at least one of organic or inorganic additives may be added to the electrolytic solution from the viewpoint of increasing the strength of the copper foil.

Examples of organic additives include thiourea (CH ₄ N ₂ S) or water-soluble thiourea derivatives (ethylene thiourea, etc.), glue, gelatin, polyethylene glycol, starch, and cellulose-based water-soluble polymers (carboxylmethylcellulose, hydroxy Ethylcellulose, etc.), and water-soluble polymer compounds such as polyethyleneimine and polyacrylamide.

As the inorganic additive, in addition to NaCl and HCl as a source of chloride ions, sodium tungstate, ammonium tungstate, or the like can be used as a source of very trace metal elements.

It is preferable to add 1 to 30 mg/L of chloride ions as an inorganic additive to the electrolytic solution, and 3 to 19 mg/L of thiourea or a water-soluble thiourea derivative as an organic additive is preferable.

In addition, the liquid temperature of the electrolytic solution is preferably adjusted to 40 to 60°C and the average current density on the surface of the cathode electrode is adjusted to 40 to 60 A/dm 2.

By the way, it is common that the strengthening of the copper foil is usually performed by adding an additive to the electrolyte. The effect of the additive is to control the injection of impurities into the foil, or the crystal orientation and grain size, mainly by adsorbing the additive to the crystal nuclei of the copper surface layer in the electrolysis stone.

However, the rate at which nucleation and growth occurs varies depending on the concentration of the electrolytic solution, current density, liquid temperature, and production conditions such as the type of additive and its concentration. In particular, in the case of conditions for the purpose of increasing strength, in many cases, nuclear growth becomes dominant.

The strength of the copper foil can be increased by adsorbing the additive to the copper crystal grains and further being blown into the copper foil, but it means that the core growth is dominant, that is, the adsorption point of the additive tends to be sparse. The high-strength copper foil produced under such conditions is liable to cause uneven strength.

In the present invention, for example, by miniaturizing and smoothing the initial electrodeposition layer of copper by the following method, the adsorption point of the additive can be made uniform in the plane direction of the copper foil, and thus the tensile strength in the width direction of the copper foil It has been found that the unevenness in intensity can be reduced.

Specifically, in addition to the conventional thinning process, it is preferable to use periodic reverse (PR) pulse electrolysis only during initial electrodeposition.

In the case of conventional thinning using a direct current, copper nuclei are generated on the cathode substrate, and copper grows from the nuclei.

However, by using PR pulse electrolysis at the time of initial electrodeposition, the deposition process of copper (at the time of positive pulse energization) and the dissolution process (at the time of negative pulse energization) are repeated at the time of generation of crystal nuclei of copper. The shape of the copper crystal nuclei generated in the precipitation step is reduced by a subsequent dissolution step. In the deposition step following the dissolution step, in addition to the smaller copper crystal nuclei, new copper crystal nuclei are generated also on the cathode substrate. By these repetitions, fine nucleation is obtained, and the initial electrodeposition layer is refined and smoothed. As a result, it is considered that the adsorption point of the additive is uniformly obtained.

Suitable conditions for PR pulse electrolysis are as follows, for example.

Constant pulse current density I _on : 20∼80A/d㎡

Positive pulse energization time t _on : 50 to 200 milliseconds (㎳)

Sub-pulse current density I _rev : -80∼-20A/d㎡

Sub-pulse energization time t _rev : 50 to 200 milliseconds (ms)

Pulse stop time t _off : 50 to 200 milliseconds (ms)

Number of repetitions of positive and negative pulses: 10 to 30 times

In the PR pulse electrolysis as described above, in particular, from the viewpoint of obtaining a homogeneous initial electrodeposition layer, it is calculated by the product of the positive pulse current density I _on (A/dm 2) and the positive pulse current application time t _on (milliseconds). The negative pulse accumulated current value calculated by multiplying the positive pulse accumulated current value Q1 (=I _on × t _on ) and the sub pulse current density I _rev (A/dm2) and the sub pulse current-carrying time t _rev (milliseconds) It is preferable that Q2 (=I _rev × t _rev ) satisfies the relationship of the following formula (i).

0.5≤｜Q2/Q1｜≤0.9 ···(i)

When the absolute value |Q2/Q1| of the ratio of the negative pulse integrated current value Q2 to the positive pulse integrated current value Q1 is larger than 0.9, the contribution of the dissolution process is large, and the total amount of precipitated nuclei of copper tends to be insufficient, Moreover, when it is smaller than 0.5, the contribution of the precipitation step is large, and there is a tendency that it is difficult to obtain fine nucleation.

According to the above-described method, it is possible to form a very thin, homogeneous initial electrodeposition layer at the minimum required level, and accordingly, in a subsequent step, a uniform precipitation layer in the thickness direction of the copper foil is obtained. Therefore, the additive is uniformly adsorbed on both surfaces of the copper foil in the plane direction and the thickness direction, and a high-strength electrolytic copper foil with small variation in strength in the width direction is obtained.

Moreover, as an apparatus suitable for manufacturing copper foil by the above-described method, a manufacturing apparatus as shown in FIG. 1 is mentioned, for example. 1 shows a schematic diagram of a manufacturing apparatus.

As shown in FIG. 1, the manufacturing apparatus 1 is mainly comprised with the cathode drum 11, the electrode 12 for PR pulses, the anode 13, and the bathtub 14. The PR pulse electrode 12 and the anode 13 are formed to face the cathode drum 11, and an electrolyte solution 20 is supplied therebetween. The cathode drum 11 rotates at a constant speed in the direction of the arrow 11a, and each of the PR pulse and the DC current is energized between each anode between the PR pulse electrode 12 and the anode 13, so that the cathode drum ( Copper precipitates on the surface of 11). The copper deposited on the surface of the cathode drum 11 is finally peeled off in the direction of the arrow 30a, and is stripped as the copper foil 30. In addition, in the manufacturing apparatus 1, the outside of the bathtub 14 and various pipes, etc. are omitted, but the electrolyte solution 20 is continuously supplied from the outside of the bathtub 14 in the direction of arrow 20a. In addition, the electrolyte solution 20 after passing between the cathode drum 11 and the PR pulse electrode 12 and the anode 13 passes through a discharge pipe and is discharged to the outside of the bathtub 14. .

The electrolytic copper foil of the present invention may further surface-treat at least one of the surface of the copper foil, if necessary.

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 further chromating treatment on the various plating layers. Inorganic rust prevention treatment, such as, or organic rust prevention treatment, such as benzotriazole, and a silane coupling agent treatment, etc. are mentioned. In addition to rust prevention, these surface treatments increase the adhesion strength with the active material when used as a negative electrode current collector of, for example, a lithium ion secondary battery, and serve to prevent a decrease in the charge/discharge cycle efficiency of the battery. These rust prevention treatments are generally treated with a very thin thickness relative to the thickness of the copper foil. Therefore, there is almost no effect on tensile strength and the like.

Before performing the above surface treatment on the copper foil, it is also possible to perform roughening treatment on the copper foil surface as necessary. As the roughening treatment, for example, a plating method, an etching method, or the like can be suitably employed. These roughening treatments play a role of further improving the adhesion to the active material and the like when the copper foil is used as a negative electrode current collector of a lithium ion secondary battery. In addition, even when copper foil is used in the production of a printed wiring board, the roughening treatment serves to enhance the adhesion to the insulating substrate. In addition, in the production of a printed wiring board, from the viewpoint of satisfactory formation of a fine circuit, the roughening treatment is preferably controlled to be a roughened surface having a desired surface property, particularly a desired development area ratio (Sdr). Further, the roughening treatment is also generally treated with a very thin thickness relative to the copper foil thickness. Therefore, there is almost no effect on tensile strength and the like.

As the roughening by the plating method, an electrolytic plating method and an electroless plating method can be employed. Roughened particles can be formed by metal plating made of one metal of Cu, Co, and Ni, or alloy plating containing two or more of these metals.

In addition, the roughening by the etching method is preferably a method by physical etching or chemical etching, for example. For example, as physical etching, the method of etching by sand blasting etc. is mentioned. In addition, as chemical etching, a method of etching with a processing liquid or the like can be mentioned. In particular, in the case of chemical etching, a known treatment liquid containing an inorganic or organic acid, an oxidizing agent, and an additive can be used as the treatment liquid.

Hereinafter, a preferred example of the roughening treatment by the plating method will be described in detail.

The roughening treatment can be performed by sequentially performing roughening plating treatment 1 and roughening plating treatment 2 on at least one surface of the copper foil serving as the base (hereinafter, simply referred to as "copper foil base"). Preferred conditions for roughening plating treatment 1 and roughening plating treatment 2 are as follows. In addition, the following conditions are a preferred example, and the type and amount of additives, and electrolysis conditions can be appropriately changed and adjusted as necessary within a range that does not interfere with the effects of the present invention.

·Harmonic plating treatment 1

Copper sulfate: 18-23 g/L as copper concentration

("As copper metal, it means "copper sulfate containing an amount equivalent to 18 to 23 g/L". The same applies below.)

Sulfuric acid: 96-105 g/L

Cobalt(II) sulfate heptahydrate: 2.8-4.2 g/L as cobalt concentration

Liquid temperature: 32~40℃

Current density: 32∼36A/dm²

Time: 1 second to 2 minutes

·Harmonic plating treatment 2

Copper sulfate: 45-55 g/L as copper concentration

Sulfuric acid: 112-121 g/L

Liquid temperature: 59~64℃

Current density: 6-12A/dm2

Time: 1 second to 2 minutes

Particularly, when the copper foil of the present invention is used for a printed wiring board, the development area ratio (Sdr) on the roughened surface of the copper foil is 20% or more from the viewpoint of achieving both adhesion to the insulating substrate and formation of a good microcircuit. It is effective to control in the range of 200% or less. The roughening treatment surface having such a desired surface property can be produced by satisfying the conditions of the roughening treatment.

Further, even in the case of performing the above-described surface treatment after the roughening treatment, since the surface treatment such as rust prevention treatment is treated to have a very thin thickness, there is little influence on the development area ratio Sdr of the roughening treatment surface. Therefore, the expanded area ratio Sdr of the roughened surface adjusted by the roughening treatment described above is maintained even after surface treatment such as rust prevention treatment.

<Negative electrode for lithium ion secondary battery and lithium ion secondary battery>

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 according to the present invention, even when a plurality of stripe coatings are performed in battery production, wrinkles, fractures, shape defects of the slit cross section, and the like are less likely to occur, and the productivity of the battery can be improved.

Since 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, durability during battery manufacturing and charging/discharging is improved. Further, a lithium ion secondary battery using such a negative electrode has a good product yield at the time of manufacture and also has excellent battery characteristics (eg, cycle characteristics).

The negative electrode for a lithium ion secondary battery can be formed by a known method using the copper foil of the present invention. For example, the negative electrode for a lithium ion secondary battery is formed by applying a slurry containing carbon particles or the like as a negative electrode active material layer on the surface of a copper foil, drying, and further pressing.

In addition, a lithium ion secondary battery can be formed by a known method using the negative electrode.

<Copper clad laminated board and printed wiring board>

The copper foil according to the present invention can also be used as a copper clad laminate and a printed wiring board provided with the same. By using the copper foil according to the present invention, it is possible to suppress the occurrence of wrinkles due to pressing when the copper foil and the insulating substrate are thermocompressed during the production of a printed wiring board, and the productivity of the printed wiring board can be improved. .

It is preferable that the copper foil of the present invention used for manufacture of a printed wiring board has a roughened surface on at least one surface of the copper foil, and the development area ratio (Sdr) of the roughened surface is 20% or more and 200% or less. According to such a copper foil, generation|occurrence|production of a wrinkle defect by a press can be suppressed, and formation of favorable fine wiring can also be made compatible.

It is preferable that the copper clad laminated board includes the copper foil of the present invention and a resin substrate laminated on the roughened surface of the copper foil. Such a copper clad laminated plate can be formed by a known method using the copper foil of the present invention. For example, a copper clad laminate is produced by laminating and bonding a copper foil having a roughened surface on at least one surface and an insulating substrate (resin substrate) so that the roughened surface (adhesive surface) and a resin substrate face each other. Examples of the insulating substrate include a flexible resin substrate or a rigid resin substrate, but the copper foil of the present invention is particularly suitable in combination with a rigid resin substrate.

In addition, when manufacturing a copper clad laminated board, it is good to manufacture by bonding the surface-treated copper foil which has a silane coupling agent layer and an insulating substrate by a heat press. In addition, a copper clad laminated plate produced by applying a silane coupling agent on an insulating substrate and bonding an insulating substrate coated with a silane coupling agent and a surface-treated copper foil having a rust-preventing layer on the outermost surface by a hot press is also provided. It has the same effect as

In addition, it is preferable that the printed wiring board is provided with the said copper clad laminated board. Such a printed wiring board can be formed by a known method using the copper clad laminate.

By the way, among printed wiring boards, it is desired to highly integrate various electronic components for build-up wiring boards, and in response to this, high-density wiring patterns are also required, and fine line widths, wiring patterns of line pitches, and so-called fine pattern printed wiring boards are required. Is required. For example, in a multilayer board used for a server, a router, a communication base station, a vehicle-mounted board, or a multilayer board for a smartphone, a printed wiring board having high-density ultrafine wiring (hereinafter referred to as "high-density wiring board") is required.

High-density wiring boards of AnyLayer (connecting layers with laser vias with high degree of freedom of placement) are mainly used for main boards of smartphones, but recently fine wiring has been made, and line width and line pitch (hereinafter referred to as ``L&S'') Each wire is required to be 30 μm or less. [0003] High-density wiring boards have conventionally been manufactured by a subtractive method using a photoresist in a printed wiring board manufacturer, and it is known that it is effective to reduce the thickness of the copper foil in order to miniaturize L&S. However, in the case of collectively molding a high-density wiring board with a large area exceeding 500 mm, if the thickness is a copper foil having a thickness of 9 µm or less, there is a problem that a wrinkle occurs in the copper foil after pressing the insulating resin and the copper foil.

In response to such a problem, for example, Japanese Patent No. 6615573 discloses a technique for forming fine wiring by minimizing the average crystal grain size of the bulk of the ultrathin copper layer. However, since no countermeasure against wrinkles has been taken, copper foil In this thin case, defects were frequent in the press process.

On the other hand, since the copper foil of the present invention has a small variation in tensile strength in the width direction as described above, it is possible to reduce the occurrence of wrinkle defects due to the pressing process even in the case of forming a thin layer and collectively forming a high-density wiring board. Productivity can be improved in the manufacture of a high-density wiring board.

As mentioned above, although the embodiment of this invention was demonstrated, the said embodiment is only an example of this invention. The present invention includes all aspects included in the concept of the present invention and the scope of the claims, and can be variously modified within the scope of the present invention.

Example

Hereinafter, the present invention will be described in more detail with reference to examples, but the following is an example of the present invention.

(Production Examples 1 to 9 and Comparative Production Examples 1 to 4)

As shown in Fig. 1, between a cathode drum 11 made of titanium (1200 mm in width and 2100 mm in diameter), an electrode 12 for PR pulses formed to face the cathode drum 11, and an insoluble anode 13 An electrolyte solution 20 is supplied to the cathode, while the cathode drum 11 is rotated at a constant speed, a PR pulse and a direct current are applied between the anodes, thereby depositing copper on the surface of the cathode drum 11 and having a thickness of 10 μm. Copper foil (30) was produced. After that, the copper foil 30 was peeled off from the cathode drum 11, both ends were cut, and wound up in a roll shape to obtain a copper foil having a width direction dimension of 1100 mm.

In addition, in any of Production Examples 1 to 9 and Comparative Production Examples 1 to 4, the electrolytic solution 20 was prepared with a copper concentration of 80 g/L, a sulfuric acid concentration of 100 g/L, and a chloride ion concentration of 20 mg/L. A sulfuric acid-copper sulfate electrolytic solution was used. In addition, 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 kinds of additives added to the electrolytic solution, their concentration, and the electrolytic conditions of PR pulse electrolysis were adjusted as shown in Table 1 for each of Production Examples 1 to 9 and Comparative Production Examples 1 to 4. . In addition, the rotation speed of the cathode drum 11 was appropriately adjusted according to the electrolytic conditions so that the thickness of the copper foil 30 was 10 µm.

In addition, among the kinds of additives shown in Table 1, "thiourea" and "ethylene thiourea" all used products manufactured by Tokyo Chemical Industry Co., Ltd.

(Comparative Production Example 5)

In Comparative Production Example 5, copper foil 30 was obtained in the same manner as in Production Example 1, except that the PR pulse was not applied between the anodes and copper was deposited on the surface of the cathode drum 11.

(Comparative Production Example 6)

In Comparative Production Example 6, copper foil 30 was obtained in the same manner as in Production Example 2, except that the PR pulse was not applied between the anodes and copper was deposited on the surface of the cathode drum 11.

(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, and each measurement was performed at room temperature unless otherwise noted. The results are shown in Table 2.

<Production of Foundation Copper Foil>

As the copper foil in a normal state, copper foil in an unheated state as manufactured was used.

In addition, the copper foil in a state after heat treatment at 150°C for 1 hour is obtained by heating the copper foil in a normal state in an inner gas oven (INH-21CD-S, manufactured by Koyo Thermo Systems Co., Ltd.) for 1 hour at 150°C. , Cooled to room temperature was used.

Each copper foil was cut at intervals of 100 mm from one end in the width direction to the other end, and 11 cut copper foils (100 mm×200 mm, thickness 10 μm) corresponding to each state were obtained.

<Tensile test>

Tensile test was conducted using a tensile tester (type 1122, manufactured by Instron), IPC-TM-650 using two types of cut copper foil as a measurement object, a normal state and a state after heat treatment at 150°C for 1 hour. Conducted in accordance with the regulations of

First, with a position of 10 mm from one end (cut end) in the width direction of one cut copper foil as a starting point, test pieces (0.5 inch x 6 inch) having a width direction dimension of 0.5 inch, 5 mm apart in the width direction. Cut out the dog. Using the obtained test piece, tensile strength and elongation were measured under conditions of a distance of 70 mm between chuck and a tensile speed of 50 mm/min. Here, elongation refers to the elongation rate when the test piece breaks. And the average value calculated from the obtained measured values (each N=5) was made into the tensile strength and elongation of this one cut copper foil. In the same manner, tensile strength and elongation were obtained for 10 other cut copper foils, and finally, the tensile strength and elongation of each of 11 cut copper foils were averaged, respectively, and the average value of the tensile strength and The average height was calculated.

This measurement was performed for two types of copper foils in a normal state and a state after heat treatment at 150° C. for 1 hour, respectively.

In addition, about the copper foil in a normal state, dispersion σ ² of the tensile strength was calculated from the tensile strength of each of 11 cut copper foils.

<Expanded area ratio (Sdr)>

Measurement of the development area ratio (Sdr) is performed by measuring the surface shape using a white light interference type optical microscope (Wyko ContourGT-K, manufactured by BRUKER) using a cut copper foil in a normal state as a measurement object, and further shape analysis. Did. The shape analysis uses a high-resolution CCD camera as a 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, the lateral sampling is 0.075 μm, the speed is 1, the backscan is 10 μm, and the length is It carried out under the conditions of 10 micrometers and a Threshold of 3%, and after performing the filter processing of TermsRemoval (Cylinderand Tilt) and DataRestore (Method: legacy, iterations 5), it processed data. Specifically, it performed as follows.

First, in the center of one cut copper foil, the surface shape was measured, shape analysis was performed, and the development area ratio (Sdr) was calculated|required. In addition, the spread area ratio (Sdr) was similarly measured for 10 other cut copper foils, and finally, the measured value (N=11) of the spread area ratio (Sdr) of each of 11 cut copper foils was averaged, and the average value was It was set as the development area ratio (Sdr) of the copper foil. The results are shown in Table 2.

<Conductivity>

The electrical conductivity was measured using an Agilent 4338B milliohm meter (manufactured by Agilent Technology Co., Ltd.) using a cut copper foil in a normal state as a measurement object, according to the regulations of JIS H0505-1975. Specifically, it performed as follows.

One test piece (0.5 inch x 6 inch) was cut out from one cut copper foil, and the test piece was used, and the electrical conductivity was measured three times by a four-terminal method with a distance between terminals of 100 mm. The average value calculated from the obtained measured value (N=3) was taken as the electrical conductivity of the single cut copper foil. Further, the electrical conductivity was similarly determined for 10 other cut copper foils, and finally, the electrical conductivity (N=11) of each of 11 cut copper foils was averaged, and the average value was taken as the electrical conductivity of the copper foil. The results are shown in Table 2.

[Evaluation of lithium ion secondary battery use]

Using the copper foil produced in the above Production Example and Comparative Production Example as a negative electrode current collector, a lithium ion secondary battery was produced, and characteristic evaluation shown below was performed. The evaluation conditions of each characteristic were as follows, and each measurement was performed at room temperature unless otherwise noted. The results are shown in Table 2.

(Manufacture of positive electrode)

First, LiCoO ₂ powder, graphite powder, and polyvinylidene fluoride powder are mixed in a mass ratio of 90:7:3, and N-methylpyrrolidone and ethanol as a solvent are added thereto, followed by kneading, and a positive electrode The first paste was prepared.

Next, the obtained positive electrode paste uniformly arrived on an aluminum foil having a thickness of 15 μm. The aluminum foil on which the positive electrode paste had arrived was dried in a nitrogen atmosphere, the solvent was volatilized, and then roll-rolled to produce a sheet having an overall thickness of 150 µm. After cutting this sheet into a width of 43 mm and a length of 285 mm, an aluminum foil lead terminal was attached to one end thereof by ultrasonic welding to obtain a positive electrode.

(Production of negative electrode and evaluation of productivity)

The copper foil used for the negative electrode current collector is a copper foil in a normal state produced by the Production Example and Comparative Production Example.

First, the copper foil was cut into a strip shape (the width direction of the strip is parallel to the width direction of the copper foil) so as to have a width direction dimension of 720 mm.

Next, natural graphite powder (average particle diameter 10 µm) and polyvinylidene fluoride powder were mixed in a ratio of 90:10 by mass ratio, and N-methylpyrrolidone and ethanol as solvents were added thereto, followed by kneading. A negative electrode paste was prepared.

Subsequently, the obtained negative electrode paste was placed on both sides of the strip-shaped copper foil with a width of 300 mm and in a double stripe shape along the length direction of the copper foil. The copper foil on which the negative electrode paste had arrived was dried in a nitrogen atmosphere, the solvent was volatilized, and then roll-rolled, and compression formed so that the overall thickness became 150 µm. After that, the arrival portion was cut into a width of 43 mm and a length of 280 mm. A lead terminal of a nickel foil was attached to one end thereof by ultrasonic welding to obtain a negative electrode.

Finally, whether or not abnormalities such as wrinkles and burrs in the cut portion were observed on the copper foil were visually checked, and evaluated as the productivity of the battery. ``Excellent (◎)'' when no wrinkles or fractures occur in the copper foil, ``good (○)'' when there are any minor wrinkles or burrs in the copper foil, and at least one of wrinkles and burrs What was generated and expected to have an influence on the evaluation of the subsequent battery characteristics was evaluated as "impossible (x)".

(Production of battery and evaluation of battery characteristics)

A separator made of polypropylene having a thickness of 25 μm was sandwiched between the prepared positive electrode and the negative electrode, the whole was wound, and this was accommodated in a battery can plated with nickel on the surface of mild steel, and the lead terminal of the negative electrode was spot-welded to the tube bottom. . Then, after placing the upper cover of the insulating material, inserting the gasket, the lead terminal of the positive electrode and the aluminum safety valve were connected by ultrasonic welding, and a non-aqueous electrolyte composed of propylene carbonate, diethyl carbonate, and ethylene carbonate was added to the battery can. Injected. Thereafter, a lid was attached to the safety valve, and a closed structure lithium ion secondary battery having an external shape of 14 mm and a height of 50 mm was assembled.

A charge/discharge cycle test was performed in which the assembled battery was charged with a charge current of 100 mA until it reached 4.2 V, and the cycle of discharging it with a discharge current of 100 mA until it reached 2.4 V was counted as one cycle. The number of cycles when the discharge capacity of the battery was less than 800 mAh was taken as the cycle life (cycle characteristics), and the battery characteristics were evaluated. The results are shown in Table 2.

The cycle life was evaluated as "excellent (◎)" for 500 or more times, "good (○)" for 300 or more and less than 500 times, and "impossible (x)" for less than 300 times. The copper foil whose evaluation is "impossible (x)" indicates that it is a copper foil that is not suitable for this use. "Good (○)" indicates that it is a suitable copper foil, and among them, "excellent (◎)" indicates that it is a copper foil having better battery characteristics.

(Comprehensive evaluation)

Comprehensive evaluation was performed based on the following evaluation criteria. In addition, in this example, A and B were taken as pass levels in the comprehensive evaluation.

A (excellent): Both of the above productivity and battery characteristics are "excellent (◎)" evaluation.

B (passed): There is no "impossible (x)" evaluation on both of the above productivity and battery characteristics, and at least one of the above productivity and battery characteristics is a "good (○)" evaluation.

C (disqualified): At least one of the above-described productivity and battery characteristics is an evaluation of "impossible (x)".

As shown in Table 2, the copper foils produced in Production Examples 1 to 9 have a predetermined tensile strength in a normal state, and at this time, the variation in tensile strength in the elongated width direction is small, and also in the state after heat treatment is high. The tensile strength is maintained (Examples 1 to 9). It was confirmed that the copper foils of Examples 1 to 9 were excellent in both productivity at the time of production of a lithium ion secondary battery and battery characteristics as a lithium ion secondary battery.

On the other hand, the copper foil produced by Comparative Production Example 1 has too high tensile strength in a normal state, and thus elongation is poor (Comparative Example 1). In addition, the copper foil of Comparative Production Example 2 has low tensile strength in a normal state and a state after heat treatment (Comparative Example 2). Therefore, it was confirmed that the electrolytic copper foils of Comparative Examples 1 and 2 were inferior in battery characteristics as a lithium ion secondary battery.

In addition, the copper foil produced by Comparative Production Examples 3 to 6 has a non-uniform tensile strength in the width direction in a normal state (Comparative Examples 3 to 6). Therefore, it was confirmed that the copper foils of Comparative Examples 3 to 6 were inferior in productivity at the time of production of a lithium ion secondary battery.

(Examples 11 to 19 and Comparative Examples 13, 15 and 16)

[Evaluation of the use of printed wiring boards]

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, roughening treatment and surface treatment were performed on one surface of each copper foil under the conditions shown below, and surface-treated copper foil ( Thickness 12㎛) was obtained.

About the obtained surface-treated copper foil, the characteristic evaluation shown below was performed. The evaluation conditions of each characteristic are as follows, and each measurement was performed at room temperature unless otherwise noted. Table 3 shows the results.

(Formation of harmony treatment layer)

First, the copper foil used for the copper foil base is a copper foil in a normal state (width direction dimension 1100 mm) produced by the above Production Examples 1 to 10 and Comparative Production Examples 3, 5 and 6.

Next, roughening plating treatment 1 and roughening plating treatment 2 shown below were sequentially performed on the surface shown in Table 3 of the copper foil base to form a roughening treatment layer.

·Harmonic plating treatment 1

Copper sulfate: 21 g/L as copper concentration

Sulfuric acid: 97 g/L

Cobalt(II) sulfate heptahydrate: 3.6 g/L as cobalt concentration

Liquid temperature: 36℃

Current density: 32A/d㎡

Time: 1 to 30 seconds

·Harmonic plating treatment 2

Copper sulfate: 50 g/L as copper concentration

Sulfuric acid: 120 g/L

Liquid temperature: 62℃

Current density: 10A/dm²

Time: 1 to 30 seconds

(Formation of surface treatment layer)

Next, a nickel layer, a zinc layer, a chromate treatment layer, and a silane coupling agent layer shown below were sequentially formed on the roughened surface of the copper foil on which the roughening treatment layer was formed.

・Formation of nickel layer (underground layer)

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

Formation of zinc layer (heat-resistant layer)

Further, a zinc layer (an amount of Zn deposited 0.05 mg/dm 2) was formed on the nickel layer by electrolytic plating under the following Zn plating conditions. The plating solution used for zinc plating contains zinc sulfate heptahydrate and sodium hydroxide, and the zinc concentration is 10 g/L and the sodium hydroxide concentration is 29 g/L. Further, the temperature of the plating solution is 30°C, the current density is 5 A/dm 2, and the plating treatment time is 1 to 30 seconds.

Formation of chromate treatment layer (rust prevention treatment layer)

Further, a chromate-treated layer (an adhesion amount of Cr 0.05 mg/dm 2) was formed on the zinc layer by electrolytic plating under the following Cr plating conditions. The plating solution used for chromium plating contains chromic anhydride (CrO ₃ ), and the chromium concentration is 3.1 g/L. Further, 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, and a silane coupling agent layer was formed on the chromate treatment layer. That is, methanol or ethanol was added to the aqueous solution of the silane coupling agent and adjusted to a predetermined pH to obtain a treatment liquid. This treatment liquid was applied to the chromate-treated layer of the surface-treated copper foil, maintained for a predetermined time, and then dried with warm air to form a silane coupling agent layer. As a silane coupling agent, 3-mercaptopropyltrimethoxysilane (KBM-803, manufactured by Shin-Etsu Chemical Co., Ltd.) was used to prepare an aqueous solution of a silane coupling agent under conditions of 1.0% concentration and pH 4.0.

<Expanded area ratio of the harmonized surface (Sdr)>

About the roughened surface of the surface-treated copper foil obtained above, the development area ratio (Sdr) was measured. Measurement was performed in the same manner as the measurement for the cut copper foil. Table 3 shows the results.

(Production of copper clad laminate and evaluation of press failure)

The surface-treated copper foil obtained above was cut to a size of 200 mm x 200 mm, and the roughened surface of the surface-treated copper foil was superimposed on an FR4-based resin substrate (EI-6765, manufactured by Sumitomo Bakelite Co., Ltd.), and 170 It heated and pressurized bonding for 1 hour on conditions of degreeC and surface pressure of 1.5 MPa, and produced the copper clad laminated board. By this method, 30 copper clad laminated plates were produced, and the presence or absence of wrinkles was visually confirmed.

For the copper clad laminate in which wrinkles were confirmed, the number of wrinkle defects was counted as one sheet. In addition, the evaluation of wrinkle defects is "excellent (◎)" when the number of wrinkle defects is 0 to 1, "good (○)" when the number of wrinkle defects is 2 to 4, and "impossible" when the number of wrinkle defects is 5 or more. It evaluated as "(x)". 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 to a size of 200 mm×200 mm, and a resist 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. And the wiring pattern was formed by etching. A dry resist film was used as the resist, and a mixed solution containing copper chloride and hydrochloric acid was used as the etching solution. And the etching factor (Ef) of the obtained wiring pattern was measured. The etching factor is a value expressed by the following equation when H is the thickness (µm) of the copper foil, B is the bottom width (µm) of the formed wiring pattern, and T is the top width (µm) of the formed wiring pattern. In addition, the thickness H of the copper foil was taken as the thickness of the surface-treated copper foil. In addition, each dimension of the bottom width B and the top width T was measured using a microscope with respect to the wiring pattern when the just etch position (the position of the end of the resist and the position of the bottom of the wiring pattern are uniform).

Ef=2H/(B-T)

Evaluation of the etching factor is ``Excellent (◎)'' when the Ef value is 3.5 or more, ``Good (○)'' when the Ef value is 2.6 or more and less than 3.5, and ``Good (○)'' when the Ef value is less than 2.6. It evaluated by making it impossible (x)". Table 3 shows the Ef value and evaluation results.

In addition, when the value of Ef is small, the verticality of the sidewalls in the wiring pattern collapses, and when a fine wiring pattern with a narrow line width is formed, a molten residue of copper foil occurs between adjacent wiring patterns, and a short circuit occurs. There is a risk of doing so, but there is a risk of disconnection.

(Evaluation of adhesion)

The surface-treated copper foil obtained above was cut to a size of 200 mm x 200 mm, and the roughened surface of the surface-treated copper foil was overlaid on an FR4-based resin substrate (same as above) for 2 hours under conditions of 170°C and a surface pressure of 1.5 MPa. , Heating and pressure bonding to prepare a copper clad laminate.

Using the produced copper clad laminate as a sample for measurement, copper foil was etched to form circuit wiring with a width of 1 mm, and a test piece was prepared. Next, the resin substrate side of the test piece was fixed to the stainless steel plate with a double-sided tape, and the circuit wiring portion (copper foil portion) was pulled in a 90-degree direction at a rate of 50 mm/min, peeled off, and peel strength (kN /m) was measured. The measurement of the peel strength was performed using a Tensilon universal material testing machine (manufactured by A&D Co., Ltd.).

The evaluation of adhesion is ``good (○)'' when the peel strength (kN/m) is 0.6 kN/m or more, and ``impossible (x)'' when the peel strength (kN/m) is less than 0.6 kN/m. And evaluated. Table 3 shows the evaluation results.

(Comprehensive evaluation)

Comprehensive evaluation was performed based on the following evaluation criteria. In addition, in this example, A and B were taken as pass levels in the comprehensive evaluation.

A (excellent): Both of the above-described wrinkle defects and etching factors were evaluated as "excellent (⊚)", and the adhesion was "good (○)".

B (passed): There is no "impossible (x)" evaluation in any of the above-described wrinkle defects, etching factors, and adhesion, and at least one of the wrinkle defects and etching factors is "good (○)" evaluation.

C (failed): At least one of the above-described wrinkle defects, etching factor, and adhesion is an evaluation of "impossible (x)".

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

As shown in Table 3, the copper foils of Examples 1 to 9 produced in Production Examples 1 to 9 have a particularly small variation in tensile strength in the elongated width direction. When a copper clad laminate was produced using the copper foils of Examples 1 to 9, it was confirmed that the occurrence of wrinkles due to pressing during production could be effectively suppressed (Examples 11 to 19).

Further, it was confirmed that a printed wiring board having good adhesion and a large etching factor was obtained by performing surface treatment on the surfaces of the copper foils of Examples 1 to 9 so that the development area ratio (Sdr) of the roughened surface was within a predetermined range. (Examples 11 to 19).

On the other hand, the copper foils of Comparative Examples 3, 5, and 6 produced by Comparative Production Examples 3, 5 and 6 have a non-uniform tensile strength in the normal state in the width direction. Therefore, when a copper clad laminate was produced using the copper foils of Comparative Examples 3, 5 and 6, it was confirmed that wrinkles were formed by pressing (Comparative Examples 13, 15 and 16).

1: manufacturing device
11: cathode drum
11a: drum rotation direction
12: PR pulse electrode
13: anode
14: bathtub
20: electrolyte
20a: electrolyte supply direction
30: copper foil
30a: peeling direction

Claims (11)

An electrolytic copper foil in which the tensile strength measured using each cut copper foil obtained by cutting the electrolytic copper foil at intervals of 100 mm from one end to the other end in the width direction satisfies the following requirements (I) to (III).
-Requirement (I): The average value of the tensile strength of each of the cut copper foils in the normal state is 400 MPa or more and 650 MPa or less.
-Requirement (II): The dispersion σ ² of the tensile strength of each of the cut copper foils in a normal state is 18 [MPa] ² or less.
-Requirement (III): The average value of the tensile strength of each of the cut copper foils in a state after being heat-treated at 150°C for 1 hour is 350 MPa or more. The method of claim 1,
An electrolytic copper foil having a width direction dimension of 600 mm or more. The method according to claim 1 or 2,
The electrolytic copper foil, wherein the average value of elongation in a normal state of each of the cut copper foils is 5.3% or more. The method according to any one of claims 1 to 3,
Electrolytic copper foil with a conductivity of 88% IACS or more. The method according to any one of claims 1 to 4,
An electrolytic copper foil in which the developed area ratio (Sdr) of the glossy surface is 12% or more and 27% or less. The method according to any one of claims 1 to 5,
Electrolytic copper foil used as a negative electrode current collector of a lithium ion secondary battery. A negative electrode for lithium ion secondary batteries using the electrolytic copper foil according to claim 6. A lithium ion secondary battery using the negative electrode for lithium ion secondary batteries according to claim 7. It has a roughened surface on at least one surface of the electrolytic copper foil according to any one of claims 1 to 5,
The electrolytic copper foil in which the developed area ratio (Sdr) of the roughened surface is 20% or more and 200% or less. A copper clad laminate comprising the electrolytic copper foil according to claim 9 and a resin substrate laminated on the roughened surface of the electrolytic copper foil. A printed wiring board comprising the copper clad laminate according to claim 10.

Images