JP5740052B2 - Electrolytic copper foil and method for producing the same - Google Patents

Description

  The present invention relates to an electrolytic copper foil used for a negative electrode current collector of a high capacity lithium ion secondary battery using an alloy negative electrode active material.

  Conventionally, electrolytic copper foil has been used in various fields including rigid printed wiring boards, flexible printed wiring boards, electromagnetic wave shielding materials, and battery current collectors.

  Among these fields, in the field of flexible printed wiring boards (hereinafter referred to as “FPC”) bonded to a polyimide film, a hard disk drive (hereinafter referred to as “HDD”) suspension material or tape automated bonding (hereinafter referred to as “FPC”). There has been a demand for improving the strength of copper foil as a material called “TAB”.

  The suspension mounted in the HDD is a wiring-integrated suspension in which the flying head buoyancy and the positional accuracy are stable with respect to the disk as the storage medium from the wire type suspension that has been used conventionally as the capacity of the HDD increases. The majority have been replaced.

  This wiring-integrated suspension includes (1) a type of flexible printed circuit board called FSA (Flex Suspension Assembly) method, which is bonded using an adhesive, (2) CIS (Circuit Integrated Suspension) method A type in which amic acid, which is a precursor of polyimide resin, is shaped, then polyimide is formed, and wiring is formed by plating the resulting polyimide. (3) TSA (trace suspension assembly) method There are three types: a type called a stainless steel foil-polyimide resin-copper foil three-layer structure that is processed into a predetermined shape by etching.

  Among them, the TSA suspension can easily form a flying lead by laminating a high-strength stainless steel foil with a copper foil, and has a high degree of freedom in shape processing and is relatively inexpensive and dimensional. Widely used because of its high accuracy.

  In the laminate formed by the TSA method, the laminate is made of a material having a stainless steel foil thickness of about 12 to 30 μm, a polyimide layer thickness of about 5 to 20 μm, and a copper foil thickness of about 7 to 14 μm. It is manufactured.

  In the production of the laminate, first, a polyimide resin precursor-containing liquid is applied onto a stainless steel foil serving as a base. After coating, after removing the solvent by preheating, further heat treatment is performed to polyimidize, and then a copper foil is superimposed on the polyimide resin layer that has been polyimidized and laminated by thermocompression bonding at a temperature of about 300 ° C. And the laminated body which consists of a stainless steel layer / polyimide layer / copper layer is manufactured.

  With this heating at about 300 ° C., there is almost no dimensional change in the stainless steel foil. However, when a conventional electrolytic copper foil is used, the electrolytic copper foil is annealed at a temperature of about 300 ° C., recrystallization proceeds and softens, and a dimensional change occurs. For this reason, the laminate is warped after lamination, and the dimensional accuracy of the product is lowered.

In order to prevent warping of the laminated body after lamination, it is required to provide a copper foil that has as small a dimensional change as possible when heated.
Conventionally, a rolled copper alloy foil is used as a copper foil that satisfies this requirement. The rolled copper alloy foil is not easily annealed at a temperature of about 300 ° C., has little dimensional change during heating, and little mechanical strength change.

Rolled copper alloy foil is a copper alloy containing copper as a main component and containing at least one element other than copper, such as tin, zinc, iron, nickel, chromium, phosphorus, zirconium, magnesium, and silicon, by rolling. Foil. Some of these rolled copper alloy foils are not easily annealed by heating at about 300 ° C. depending on the type and combination of elements, and some of the tensile strength, 0.2% yield strength, elongation, etc. do not change so much.
For example, a rolled copper alloy foil such as Cu-0.2 mass% Cr-0.1 mass% Zr-0.2 mass% Zn (Cu-2000 ppm Cr-1000 ppm Zr-2000 ppm Zn) can be used as an HDD suspension material in addition to a TSA suspension. It is preferably used.

Also in the TAB material, as in the case of the TSA suspension and the HDD suspension material, it is required to increase the strength of the copper foil.
In a TAB product, a plurality of terminals of an IC chip are directly bonded to inner leads (flying leads) arranged in a device hole located substantially at the center of the product.
Bonding at this time is performed by applying a constant bonding pressure by instantaneously energizing and heating using a bonding apparatus (bonder). At this time, there is a problem that the inner lead obtained by etching the electrolytic copper foil is excessively stretched by being pulled by the bonding pressure.

By increasing the strength of the electrolytic copper foil, it becomes difficult for the inner leads to sag and break. Therefore, if the strength of the electrolytic copper foil is too small, there is a problem that sagging occurs in the inner lead due to plastic deformation, and if it is significant, it breaks.
On the other hand, by reducing the roughness of the copper foil surface, when the TAB wiring is formed by etching, the side walls of the wiring can be prevented from being excessively thinned by over-etching, and the thin line can be formed by etching. is there. The reason for this is as follows. In general, the HDD and TAB wirings are formed by etching after applying a copper foil to a polyimide base material after heat laminating. At this time, if the roughness of the copper foil surface is rough, the copper foil bites into the polyimide surface, and if the biting portion is removed by etching, the side wall of the wiring is over-etched and the line width is reduced. In order to avoid this, it is desirable to reduce the roughness of the copper foil surface.
Therefore, in order to reduce the line width of the inner lead, the electrolytic copper foil to be used is required to have a roughened surface with low roughness and to have high strength.
In this case as well, the copper foil or copper alloy foil needs to have high strength in a normal state (25 ° C., 1 atm, the same applies hereinafter), and high strength even after heating.

  In the case of TAB use, a two-layer FPC in which a copper foil and a polyimide layer are bonded together, or a three-layer FPC in which a copper foil, a polyimide layer, and an adhesive layer are bonded together is used. In a three-layer FPC, an epoxy adhesive is used when polyimide is laminated to a copper foil, and is laminated at a temperature of about 180 ° C. In a two-layer FPC using a polyimide-based adhesive, bonding is performed at a temperature of about 300 ° C.

  Conventional high-strength electrolytic copper foil has a high mechanical strength in the normal state by using organic additives, and the mechanical strength hardly changes even when heated at around 180 ° C. When heated with, annealing and recrystallization proceed, so that it softens rapidly and mechanical strength may be significantly reduced.

  It has been found that the increase in strength due to organic additives occurs because organic molecules derived from the additives incorporated into the copper foil during electrolysis inhibit recrystallization. Since conventional high-strength foils are recrystallized at about 300 ° C. because of the decomposition temperature of organic molecules, studies have been made to use inorganic additives having higher decomposition temperatures.

  For example, in Patent Document 1, an electrolytic copper foil is manufactured with an electrolytic solution obtained by adding tungsten or a tungsten compound, glue (glue), and 20 to 120 mg / L of chloride ions in a sulfuric acid copper sulfate electrolytic solution. How to do is described. As its effect, it is described that the hot elongation at 180 ° C. is 3% or more, the roughness of the rough surface is large, and a copper foil with less pinholes can be produced.

Patent Document 2 describes an electrolytic copper foil containing silver (Ag).
It is said that silver is co-deposited in this electrolytic copper foil by producing an electrolytic copper foil using a sulfuric acid copper sulfate electrolytic solution to which a silver salt giving a predetermined concentration of silver ions is added.

Patent Document 3 describes a dispersion strengthened electrolytic copper foil in which copper is present as fine crystal grains and SnO ₂ is dispersed as ultrafine particles.
In Patent Document 3, copper ions, sulfate ions and tin ions and an organic additive such as polyethylene glycol are contained in a sulfuric acid copper sulfate electrolyte, and a bubbling treatment with an oxygen-containing gas is performed to add SnO ₂ into the electrolyte. It is described that ultrafine particles are produced and the dispersion strengthened electrolytic copper foil is obtained using the electrolytic solution.

Japanese Patent No. 3238278 Japanese Patent No. 3934214 JP 2000-17476 A

  Therefore, the present inventors have conducted an experiment in which electrodeposition is performed using an electrolytic solution obtained by adding tungsten or a tungsten compound to a sulfuric acid-copper sulfate electrolytic solution and further adding nickel and 20 to 120 mg / L of chloride ions based on Patent Document 1. Repeatedly, by the method described in Patent Document 1, it is possible to produce a copper foil having a target hot elongation at 180 ° C. of 3% or more, a rough surface having a large roughness and less pinholes. I confirmed that I can do it.

  However, as a result of analysis of this copper foil, it was found that this electrolytic copper foil contained almost no tungsten, and the strength decreased extremely after heating at 300 ° C. (see Comparative Example 4 described later). ).

  Also in the electrolytic copper foil of patent document 2, it turned out that mechanical strength falls remarkably when it heats at about 300 degreeC high temperature like the electrolytic copper foil using an organic additive (it mentions later. Comparative Example 14).

In the dispersion strengthened electrolytic copper foil in which SnO _{2 of} Patent Document 3 is dispersed, not only the manufacturing cost is required for bubbling, but also the conductivity is high because the particle diameter of the SnO ₂ fine particles is relatively large. The problem of being low occurred (see Comparative Example 13 described later).

  Therefore, the conventional method cannot provide an electrolytic copper foil that normally has high mechanical strength as a negative electrode current collector or wiring board material for a battery, and that is not easily lowered in mechanical strength even when heated at high temperatures. There was a problem.

  The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an electrolytic copper foil having a large mechanical strength in a normal state. More preferably, it is to provide an electrolytic copper alloy foil whose mechanical characteristics are not easily thermally deteriorated even when heated at a high temperature of about 300 ° C.

  As a result of intensive studies, the inventors have dispersed nano-inclusions containing an organic compound or an inorganic compound in a copper foil, and set the particle size of the nano-inclusions to a predetermined range, whereby a normal state is obtained. It has been found that an electrolytic copper alloy foil having a high mechanical strength can be obtained.

In particular, it has been found that by dispersing nanoinclusions formed of an inorganic compound in a copper foil, an electrolytic copper alloy foil with little thermal deterioration of mechanical strength can be obtained even when heated at about 300 ° C.
The present invention has been completed based on these findings.

In order to achieve the above-mentioned object, the following invention is provided.
(1) It has inclusions with an average particle size of 0.5 to 100 nm inside the copper crystal grains or at the grain boundaries between the copper crystal grains, and the inclusions contain an inorganic compound and / or an organic compound, The inorganic compound includes an oxide of one or more metal elements selected from the group consisting of tungsten, molybdenum, titanium, and tellurium, and the organic compound is thiourea, ethylenethiourea, tetramethylthiourea, 1,3-dimethyl- An electrolytic copper foil comprising one or more thiourea-based organic compounds selected from the group consisting of 2-thiourea and 1,3-diethyl-2-thiourea.
(2) The electrolytic copper foil according to (1), wherein the average grain size of the crystal grains is 100 to 600 nm.
(3) The electrolytic copper foil according to (1) or (2), wherein an average particle size of the inclusions is 0.5 to 50 nm.
(4) The electrolytic copper foil according to (3), wherein the inclusions have an average particle size of 0.5 to 20 nm.
(5) The electrolytic copper foil according to any one of (1) to (4), wherein the inclusion includes an inorganic compound, and the content of the metal element in the electrolytic copper foil is 10 to 2610 ppm. .
(6) The electrolytic copper foil according to any one of (1) to (4), wherein a content of chlorine in the electrolytic copper foil is less than 1 ppm.
(7) A current collector made of the electrolytic copper foil according to any one of (1) to (6), and an electrode active material layer having an electrode active material formed on the surface of the current collector. An electrode for a non-aqueous electrolyte secondary battery.
(8) A nonaqueous electrolyte secondary battery using the electrode for a nonaqueous electrolyte secondary battery according to (7).
(9) An aqueous solution containing an inorganic compound and / or an aqueous solution containing an organic compound is added to a sulfuric acid-copper sulfate-based electrolytic solution containing sulfuric acid and copper sulfate, and electrolytic deposition is performed using the electrolytic solution to form an electrolytic copper foil. An aqueous solution containing the inorganic compound is an aqueous solution in which a salt of one or more metal elements selected from the group consisting of tungsten, molybdenum, titanium, and tellurium is dissolved, and the aqueous solution containing the organic compound is thiourea, It is an aqueous solution containing one or more thiourea organic compounds selected from the group consisting of ethylenethiourea, tetramethylthiourea, 1,3-dimethyl-2-thiourea, and 1,3-diethyl-2-thiourea. A method for producing an electrolytic copper foil.
(10) The method for producing an electrolytic copper foil according to (9), wherein a chloride ion concentration in the electrolytic solution is less than 3 mg / L.

  According to the present invention, an electrolytic copper foil having a high mechanical strength in a normal state can be provided. Here, the normal state means a state where the electrolytic copper foil is placed at room temperature and normal pressure (25 ° C. and 1 atmospheric pressure) before heat treatment. Mechanical strength refers to tensile strength, 0.2% yield strength, and the like.

The schematic diagram which shows the structure of the electrolytic copper foil 1 which concerns on this embodiment. A TEM image (under focus image) of an electrolytic copper foil containing W before heat treatment. The TEM image (under focus image) of the electrolytic copper foil containing W after performing heat processing. The high resolution STEM image (HAADF-STEM image) of the electrolytic copper foil containing W after performing heat processing. A HAADF-STEM image of a copper foil containing both ethylenethiourea and tungsten. TEM image (under focus image) of copper foil not containing W. 7A is a schematic diagram of the SAXS (USAXS) apparatus, FIG. 7B is a diagram showing a case where scattered X-rays are measured, and FIG. 7C is a case where transmitted X-rays are measured. Figure. FIG. 8A is a diagram showing the SAXS measurement results before and after baking (heat treatment) of the electrolytic copper foil containing W, and FIG. 8B is before and after baking of the electrolytic copper foil containing Mo. The figure which shows the SAXS measurement result of FIG. 8, FIG.8 (c) is a figure which shows the SAXS measurement result before baking after baking of the electrolytic copper foil containing W and TU (thiourea). The SAXS measurement result before baking of the electrolytic copper foil containing W made one-dimensional. FIG. 10A is a diagram showing a fitting result of SAXS measurement of an electrolytic copper foil containing W before firing, and FIG. 10B is a diagram similarly showing a particle size distribution. FIG. 11A is a view showing the XAFS measurement result in the vicinity of the W absorption edge of the electrolytic copper foil containing W before firing, FIG. 11B is a view in the vicinity of the Mo absorption edge of the electrolytic copper foil containing Mo before firing. The figure which shows a XAFS measurement result.

(Electrolytic copper foil)
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 illustrates an electrolytic copper foil 1 according to an embodiment of the present invention. The electrolytic copper foil 1 has a large number of crystal grains 3 of copper, and has inclusions 5 inside the crystal grains 3 and at grain boundaries between the crystal grains 3.

  The crystal grains 3 are fine crystal grains of copper as a base material, and the average particle diameter is preferably 100 to 600 nm. Here, the average particle size of the crystal grains 3 is a value obtained by averaging the lengths of the major axes of the respective particles. The crystal grain 3 has a substantially spherical shape with an aspect ratio of a major axis and a minor axis of about 0.5 to 2.0. The average grain size of the crystal grains 3 can be obtained by image processing the observed image of the polished surface of the copper foil by SIM (scanning ion microscopy).

  The inclusions 5 are fine particles containing an organic compound and / or an inorganic compound, and are present as fine particles in the copper foil without forming an alloy with the base material copper. The average particle diameter (diameter) of the inclusion 5 is 0.5 to 100 nm, preferably 0.5 to 50 nm, and more preferably 0.5 to 20 nm.

  The inorganic compound contained in the inclusion 5 preferably contains one or more metal elements selected from the group consisting of tungsten, molybdenum, titanium, and tellurium, and is preferably a metal oxide thereof. These metal species exist as oxides in a liquid having a pH of 4 or less.

The metal present as an oxide in an acidic solution having a pH of 4 or lower is, for example, M. Pourbaix's Atlas of electrochemical.
equilibria in aqueous solutions. In the potential-pH diagram shown in Pergamon Press (1966), DLS (dynamic light) is a metal component that exists as an oxide at a pH of 4 or less, and in which the metal component is actually added. As a result of particle size distribution measurement by a scattering method (Dynamic Light Scattering), the added metal component is a metal component detected as solid particles.

  The organic compound contained in the inclusion 5 is any one selected from the group consisting of thiourea, ethylenethiourea, tetramethylthiourea, 1,3-dimethyl-2-thiourea, and 1,3-diethyl-2-thiourea. It is preferable to contain one or more thiourea organic compounds.

  The inclusion 5 contained in the electrolytic copper foil 1 may contain only an organic compound, may contain only an inorganic compound, or may contain both an organic compound and an inorganic compound. Since the inorganic compound fine particles are not thermally decomposed even by heating at 300 ° C., the inorganic compound fine particles as the inclusion 5 can suppress the strength deterioration of the electrolytic copper foil after heating.

  The content (incorporation amount) of the metal constituting the inclusion 5 in the electrolytic copper foil is preferably 10 to 2610 ppm in terms of metal. Furthermore, 15-2610 ppm is preferable, 80-2610 ppm is preferable, 100-2500 ppm is more preferable, 110-2460 ppm is still more preferable, 210-2460 ppm is especially preferable. When the content is too small, the heat resistance effect is reduced, and for example, the tensile strength after heating at 300 ° C. becomes as low as 80% or less as a ratio to the normal tensile strength. On the other hand, when the content is too large, no further improvement is seen in the effect of improving the tensile strength, and the conductivity is lowered. In particular, when the metal constituting the inclusion 5 is tungsten, the content of tungsten in the electrolytic copper foil is preferably 280 to 2460 ppm. This is because the ratio of the tensile strength after heating at 300 ° C. for 1 hour (hereinafter abbreviated as “300 ° C. × 1H”) to the tensile strength in the normal state exceeds 80%.

  Next, the content (uptake amount) of chlorine in the electrolytic copper foil is less than 1 ppm. When the chlorine content of the electrolytic copper foil is 1 ppm or more, the amount of metal oxide incorporated is extremely reduced, and the effect of improving tensile strength and heat resistance is lowered. Further, the fact that the chlorine content is less than 1 ppm includes the case of chlorine free, that is, the chlorine content is 0 ppm.

(Method for producing electrolytic copper foil)
The electrolytic copper foil according to the present embodiment can be manufactured by the following manufacturing method.
An electrolytic copper foil is produced by adding fine particles of an organic compound such as thiourea or an inorganic compound to a copper sulfate aqueous solution, and further electrolytically depositing copper using the copper sulfate aqueous solution.
When preparing an electrolytic copper foil containing an inorganic compound, first, hydrochloric acid or water-soluble chlorine in a mixed solution of an aqueous copper sulfate solution and an aqueous solution of the metal salt of the metal so as to have a chloride ion concentration of 3 mg / L or less. An electrolyte is prepared by adding a compound. Thereafter, an electrolytic copper foil is produced by electrolytic deposition using the electrolytic solution.

1. Electrolyte composition As the electrolyte, a copper sulfate-containing aqueous solution adjusted to a copper ion concentration of 50 to 200 g / L, a free sulfate ion concentration of 30 to 400 g / L, and a chloride ion concentration of 3 mg / L or less is used as a basic electrolyte composition. . Here, in the present invention, not containing chloride ions means that the chloride ion concentration is 3 mg / L or less.
Copper ions and free sulfate ions can be obtained by adjusting an aqueous copper sulfate solution so as to give the respective ion concentrations. Alternatively, the concentration of these ions may be adjusted by adding sulfuric acid to an aqueous copper sulfate solution that gives a predetermined copper ion concentration.
The chloride ion may be provided by hydrochloric acid or a water-soluble chlorine-containing compound. As the water-soluble chlorine-containing compound, for example, sodium chloride, potassium chloride, ammonium chloride and the like can be used.

2. Addition of inorganic compound inclusions By adding a metal salt aqueous solution in which the metal salt is dissolved to an electrolyte solution having a pH of 4 or less, preferably a sulfuric acid electrolyte solution, metal oxide fine particles and ultrafine particles are added to the electrolyte solution. And is taken into the copper foil during electrolytic deposition. In the present specification, “fine particles and ultrafine particles” refer to particles having a smaller particle diameter than normal fine particles (about 20 nm).
Any metal salt may be used as long as it is ionized in a solvent such as water (pH higher than 4 and lower than 9), alkali (pH 9 or higher), hot concentrated sulfuric acid, and becomes an oxide at pH 4 or lower. There is no particular limitation. Examples of these metal salts include oxyacid salts when the metal is W or Mo, and sulfates when the metal is Ti. For example, tungstates such as sodium tungstate, potassium tungstate, and ammonium tungstate, molybdates such as sodium molybdate, potassium molybdate, and ammonium molybdate, and titanium salts such as titanium sulfate can be used.
In addition, tellurium is usually classified as a semi-metal and therefore does not strictly correspond to a metal salt, but ionizes in a solvent and becomes an oxide at pH 4 or lower. For example, tellurium oxide is ionized in hot concentrated sulfuric acid and then added to an electrolyte having a pH of 4 or less, tellurium dioxide or tellurium trioxide is deposited. Further, tellurium dioxide or tellurium trioxide precipitates even when an aqueous solution in which telluric acid is dissolved in an alkaline environment is adjusted to pH 4 or lower.

  The concentration of the metal element in the electrolytic solution is preferably 1 mg / L to 500 mg / L (as the metal), more preferably 10 mg / L to 250 mg / L (as the metal). When this concentration is too low, the target metal is not sufficiently taken into the copper foil. On the other hand, if this concentration is too high, the target metal is excessively taken into the copper foil, and the electrical conductivity is lowered, or the heat resistance improving effect is saturated and the heat resistance is lowered. The tensile strength may decrease. In particular, when tungsten is used as the metal element to be added, the concentration of the metal element in the electrolytic solution is preferably 10 to 500 mg / L, and more preferably 30 to 380 mg / L.

  In this embodiment, in order to adjust to the predetermined chloride concentration, it is preferable that water used for preparing the electrolytic solution or the metal salt aqueous solution does not contain chloride ions as much as possible. In this respect, it is preferable to prepare the aqueous metal salt solution by dissolving the metal salt in pure water. Here, the pure water is preferably water containing as little metal ions and chloride ions as possible. Specifically, water having a chloride ion concentration of 3 mg / L or less is preferable, and water having a chloride ion concentration of less than 1 mg / L is more preferable.

3. Addition of organic compound inclusion When an organic compound is used as the inclusion, an organic additive is added simultaneously with or in place of the above-described metal salt aqueous solution. That is, an organic additive is added to the copper sulfate electrolyte as it is or in an aqueous solution. As this organic additive, use one or more organic compounds of thiourea, ethylenethiourea, tetramethylthiourea, 1,3-dimethyl-2-thiourea, 1,3-diethyl-2-thiourea Can do. The concentration of the organic additive in the electrolytic solution is preferably 3 mg / L to 100 mg / L, more preferably 5 to 15 mg / L.
By performing electrolytic deposition using a copper sulfate electrolyte containing an organic additive, an electrolytic copper foil containing an inclusion of an organic compound can be produced.

4). Manufacturing conditions The conditions during electrolytic deposition are as follows.
Current density 30-100 A / dm ²
Temperature 30-75 ° C
Under the above conditions, an electrolytic copper foil having a film thickness of, for example, 12 μm can be manufactured.
As a specific example, the electrolytic copper foil is produced by electrolytically depositing copper from the electrolytic solution on a rotating titanium drum, peeling it off and continuously winding it.

(Mechanism of inclusion addition)
The reason why the metal salt aqueous solution is added to the electrolytic solution is that the metal taken into the copper foil is present as ions in the aqueous solution, and this is introduced into the electrolytic solution. By adopting such a charging mode, metal oxide fine particles and ultrafine particles are formed when metal ions are converted into oxides in an electrolyte solution having a pH of 4 or lower. On the other hand, even if the metal salt is directly added to the electrolytic solution, metal oxide fine particles and ultrafine particles are not formed, and thus the effect of improving tensile strength and heat resistance cannot be obtained.

  The chloride ion in the electrolyte is suppressed to a low concentration of 3 mg / L because the specific adsorption of chlorine on the copper surface during precipitation of the metal oxide fine particles and ultrafine particles causes the metal oxide fine particles and ultrafine particles to This is to prevent inhibition of adsorption. When the concentration of chloride ions is higher than 3 mg / L, the metal uptake into the electrolytic copper foil is reduced, and the effect of improving the tensile strength and heat resistance is rapidly reduced.

(Dislocation inhibition effect)
The metal material including the copper foil is recrystallized by heating to a temperature higher than the recrystallization temperature to coarsen the crystal grains, and as a result, the strength is lowered. Here, the starting point of the recrystallization process is the movement (movement) of dislocations (unstable states such as lattice defects). In the electrolytic copper foil of the present invention, metal oxide fine particles and ultrafine particles are dispersed in the matrix, thereby inhibiting dislocation movement around the fine particles and ultrafine particles. Accordingly, dislocations in the copper foil are difficult to move, and the strength of the copper foil is increased.
Moreover, since higher energy (heat) is required for the movement of dislocations, the copper foil does not soften unless heated at a higher temperature. That is, by inhibiting the movement of dislocations, the heat resistance of the copper foil is improved.
In the present application, this is referred to as “high dislocation inhibition effect”.

(Foil thickness of electrolytic copper foil)
There is no restriction | limiting in particular in the foil thickness of the electrolytic copper foil of this embodiment, What is necessary is just to adjust according to the request | required foil thickness in a use application. For example, it may be 3 to 20 μm for a flexible printed wiring board (FPC). On the other hand, what is necessary is just to set it as 5-30 micrometers for the negative electrode collector for lithium ion secondary batteries.

(Physical properties of electrolytic copper foil)
The electrolytic copper foil of this embodiment preferably has a conductivity of 55% IACS or more, more preferably 65% IACS or more, and particularly preferably 70% IACS or more. There is no restriction | limiting in particular in the upper limit of electrical conductivity, and it may exceed 100% IACS.
The electrolytic copper foil of the present embodiment preferably has a normal tensile strength value of 500 MPa or more, and more preferably 600 MPa or more. There is no restriction | limiting in particular in the upper limit of the tensile strength in a normal state, Usually, it is 1100 Mpa or less.
In the electrolytic copper foil of the present invention, the ratio of the tensile strength value measured at room temperature after 300 ° C. heat treatment to the normal tensile strength value is preferably 50% or more, and preferably 80% or more. More preferably, this ratio is particularly preferably 90% or more. The upper limit of this ratio is not particularly limited and may exceed 100% (that is, the tensile strength increases after heating).

(Mechanism for improving mechanical strength)
In metal materials, the relationship between mechanical strength and crystal grains is said to follow the Hall-Petch rule. According to this law, the mechanical strength increases as the crystal grains become smaller. Actually, the electrolytic copper foil containing no additive has a crystal grain size of several tens of μm, and its normal mechanical strength is about 200 MPa. On the other hand, the electrolytic copper foil in the present invention has crystal grains of 100 to 600 nm and mechanical strength of 800 Mpa or more. Even if the strengthening of the electrolytic copper foil in the present invention is not caused only by the size of the crystal grain size, it can be said that the electrolytic copper foil complies with the above law to some extent.
However, when the copper foil itself is fired, crystal grains grow and become coarse. Thereby, there exists a problem that the intensity | strength of electrolytic copper foil will fall. Therefore, the electrolytic copper foil in the present embodiment is dispersed with inclusions having a pinning effect (pinning effect) for suppressing crystal growth as described below.

(Pinning effect to suppress crystal growth)
The reason why the thermal deterioration of the mechanical strength is small even at a high temperature of 300 ° C. is that no coarsening of the copper crystal grains as the parent phase has occurred. As described above, it is generally known that mechanical strength and crystal grain size follow the Hall-Petch rule. The reason why copper crystal grains do not grow in the heating process is considered to be due to the pinning effect by inclusions.
From the Gibbs-Thomson equation, the crystal grain growth force can be approximated as in equation (1).
ΔG = 4σV / D (1)
ΔG: Grain growth force, σ: Grain boundary energy, D: Grain diameter, V: Molar volume. On the other hand, the suppressive power of crystal grain growth can be approximated by the Zener-Smith model as shown in Equation (2).
ΔG _pin = πdσnV / 2 (2)
ΔG _pin : Suppression of crystal grain growth, σ: Grain boundary energy, d: Inclusion diameter, V: molar volume, n: Inclusion number density per unit area. In order to suppress crystal grain growth, it is necessary to satisfy ΔG = ΔG _pin . That is, Equation (3) is established in a state where the pinning effect is ideally exhibited.
D = 8 / πdn (3)
The crystal grain size of copper as the mother phase is 100 to 600 nm on average, the size of the precipitate is 0.5 to 100 nm, and the density of the precipitate is 1.0 × 10 ^{16 to} 1.0 × 10 ^19. Since it is the number of pieces / cm ³ , a sufficient pinning effect can be expected. The area where the pinning effect is exhibited is shown below.

Precipitate size: 0.5 to 20 nm → The pinning effect is most exhibited, and growth of crystal grains can be suppressed even at high temperatures.
Precipitate size: 20-50 nm → Although the pinning effect is exhibited, it cannot be said that the crystal growth is completely suppressed. However, before and after firing, the mechanical strength can be suppressed with a reduction of about 80%.
Precipitate size: 50 to 100 nm → A pinning effect is exhibited, but a large number of crystal grains are observed. The mechanical strength before and after firing also decreases to 60%.

Number density of precipitates: (A) 1.0 × 10 ^{18 to} 1.0 × 10 ¹⁹ pieces / cm ³ → The pinning effect is most exhibited, and growth of crystal grains can be suppressed even at high temperatures.
Number density of precipitates: (B) 1.0 × 10 ^{17 to} 1.0 × 10 ¹⁸ pieces / cm ³ → Although the pinning effect is exhibited, it cannot be said that the crystal growth is completely suppressed. However, the mechanical strength before and after firing can be suppressed by a reduction to about 80%.
Number density of precipitates: (C) 1.0 × 10 ^{16 to} 1.0 × 10 ¹⁷ pieces / cm ³ → Pinning effect is exhibited, but many coarse grains are observed. The mechanical strength before and after firing may also decrease to 60%.

Therefore, it is the combination of the size of the precipitates: 0.5 to 20 nm and the number density of the precipitates: (A) 1.0 × 10 ^{18 to} 1.0 × 10 ¹⁹ pieces / cm ³ that maximizes the pinning effect. It is.
Table 1 shows the relationship between the size, number density and mechanical strength of the precipitates based on the above theoretical considerations and experimental results.

(Durability of inclusions that are pins)
Inclusions that have a pinning effect also become ineffective when heated and destroyed. Organic compound inclusions may be decomposed by heating. However, inorganic oxides do not burn out in the temperature range of 300 ° C. In fact, the electrolytic copper alloy foil containing tungsten was still WO ₃ before and after firing. Furthermore, since the standard generation energy of oxide is lower in W than Cu, Cu does not deprive WO ₃ of oxygen in a heating environment of 300 ° C. If there is a possibility, a ternary oxide of CuWO ₄ may be generated. However, since the above-mentioned substances are present without being dissolved because the crystal structure is different from that of Cu, the pinning effect is sustained.

(Effect of this embodiment)
Since the electrolytic copper foil according to the present embodiment has inclusions in the copper crystal grains or in the grain boundaries, the mechanical strength in the normal state is high.

  In this embodiment, the electrolytic copper foil having inclusions of inorganic compounds in the copper crystal grains or at the grain boundaries prevents the inclusions from being thermally decomposed even during heat treatment at 300 ° C., thereby preventing the crystal grains from becoming coarse. Therefore, the tensile strength value after the heat treatment at 300 ° C. is high.

(Preferred embodiment)
A preferred embodiment of the present invention is an electrolytic copper foil containing tungsten with the balance being copper and inevitable impurities.
Here, the term “containing tungsten” means that tungsten oxide particles and ultrafine particles are dispersed in the base material.
The amount of tungsten contained in the electrolytic copper foil is preferably in the range of 10 to 2610 ppm, and more preferably in the range of 280 to 2460 ppm. Here, the amount of tungsten contained in the electrolytic copper foil is a content obtained by converting the tungsten component contained as each fine particle or ultrafine particle of tungsten oxide into metallic tungsten. If the content of tungsten is too small, the effect of addition hardly appears. On the other hand, if the added amount of tungsten is too large, the effect of the addition is saturated and the effect of improving the physical properties is not seen despite the high cost.

That is, in an electrolytic copper foil containing tungsten in an amount of less than 10 ppm, the mechanical strength after heating at 300 ° C. for 1 hour is lowered in the same manner as when tungsten is not contained.
As the added amount of tungsten increases, the decrease in strength after heating at 300 ° C. × 1 H decreases, but the effect becomes saturated when the content increases to some extent.
The unit “ppm” used for displaying the content of the component means “mg / kg”. Moreover, it is 0.0001 mass% = 1ppm.

The electrolytic copper foil of a preferred embodiment can be obtained by electrolyzing a copper sulfate electrolyte solution having a pH of 4 or less containing copper ions and a tungsten oxide produced from a tungsten salt at a pH of 4 or less.
The tungsten salt contained in the electrolytic solution may be any salt that dissolves in a sulfuric acid-copper sulfate solution, and examples thereof include sodium tungstate, ammonium tungstate, and potassium tungstate.

In the electrolytic copper foil of a preferred embodiment, a tungsten oxide in which tungstate ions generated from a tungsten salt changed in an electrolytic solution having a pH of 4 or less was used in the electrolytic solution having a low chloride ion concentration. By electrolytic deposition, the tungsten oxide (mainly WO ₃ , partly W ₂ O ₅ , possibly including WO ₂ ) is taken into the electrolytic copper foil as it is. Here, these tungsten oxides are dispersed as fine particles or ultrafine particles in the base copper.
That is, the electrolytic copper foil of a preferred embodiment is a sulfuric acid-copper sulfate electrolytic solution having a low chloride ion concentration, and is formed by electrolytic deposition from an electrolytic solution containing tungsten oxide. In this sulfuric acid-copper sulfate electrolyte containing tungsten oxide, tungsten oxide is formed into fine particles or ultrafine particles from tungsten salt via tungstate ions (WO ₄ ²⁻ or WO ₅ ²⁻ ). Conceivable.

  When copper is electrodeposited with a sulfuric acid-copper sulfate electrolyte containing tungsten oxide with a low chloride ion concentration to form an electrolytic copper foil, the tungsten oxide particles and ultrafine particles are adsorbed to the crystal grain boundaries, The growth of nuclei is suppressed, the crystal grains are refined, and an electrolytic copper foil having a large mechanical strength in a normal state is formed.

  The tungsten oxide fine particles and ultrafine particles present in the electrolytic copper foil remain as tungsten oxide fine particles and ultrafine particles without being bonded to or absorbed by the bulk copper crystal.

  Even when the electrolytic copper foil containing tungsten oxide is heated at a high temperature of about 300 ° C., the tungsten oxide serves to prevent the fine crystals of copper from being recrystallized by heat and coarsening the crystal grains.

  Therefore, the electrolytic copper foil of a preferred embodiment has a high mechanical strength in a normal state and a small decrease in mechanical strength even after heating at a high temperature of about 300 ° C. It has excellent characteristics that are not found in the electrolytic copper foil produced by the electrolytic solution of the system.

The electrolytic copper foil is manufactured by electrolytically depositing copper from a sulfuric acid-copper sulfate-based electrolytic solution on a rotating titanium drum, peeling the copper, and continuously winding it. The surface of the copper foil in contact with the electrolyte is called the rough surface, and the surface in contact with the titanium drum is called the glossy surface.
The electrolytic copper foil of a preferred embodiment preferably has a roughness with a roughness of Rz ≦ 2.5 μm, depending on the application. The glossy surface is a replica of a titanium drum, and Rz = 0.5 to 3.0 μm. Here, Rz refers to Rz (10-point average roughness) measured according to JIS B0601-1994.

  When using an organic compound as an inclusion, it is considered that the organic additive added to the sulfuric acid-copper sulfate electrolyte forms a compound with copper and chlorine in the electrolyte. When an electrolytic copper foil is formed by electrolytic deposition of copper with this electrolytic solution, the copper-organic additive-chlorine compound is adsorbed inside the crystal grains or at the crystal grain boundaries, and the growth of crystal nuclei is suppressed. An electrolytic copper foil which is miniaturized and has a large mechanical strength in a normal state is formed.

  However, since the inclusion contained in the electrolytic copper foil is a copper-organic additive-chlorine compound, copper is bonded or absorbed with bulk copper crystals, and the substance present in the electrolytic copper foil is an organic additive. Therefore, it is considered that these organic additives and chlorine decompose when exposed to a high temperature of about 300 ° C., resulting in a decrease in mechanical strength.

  The reason why the tensile strength decreases when heated at a high temperature of about 300 ° C. is because the inclusions present at the grain boundaries are organic compounds as described above, and the organic compounds are easily decomposed by heating at about 300 ° C. The mechanical strength is considered to decrease.

On the other hand, the electrolytic copper foil of a preferred embodiment is an electrolytic copper foil formed by electrolytic deposition from an electrolytic solution containing tungsten oxide in a sulfuric acid-copper sulfate electrolytic solution having a low chloride ion concentration. .
The tungsten component contains tungsten oxide (mainly WO ₃ , partly W ₂ O ₅ , WO ₂ ) via tungstate ion (WO ₄ ²⁻ or WO ₅ ²⁻ ) in sulfuric acid-copper sulfate electrolyte. Fine particles and ultrafine particles are formed, and are contained in the electrolytic copper foil in the form of the fine particles and ultrafine particles. As a result, growth of copper crystal nuclei is suppressed, copper crystal grains are refined, and an electrolytic copper foil having a large mechanical strength in a normal state is formed.

  Therefore, since the electrolytic copper foil of the preferred embodiment uses tungsten oxide fine particles and ultrafine particles as inclusions, unlike the case of copper-organic additive-chlorine compound, tungsten binds to the same crystal in the bulk or It is considered that tungsten oxide fine particles and ultrafine particles remain in the crystal grains or at the grain boundaries without being absorbed.

For this reason, even when exposed to a high temperature of about 300 ° C., the tungsten oxide fine particles and ultrafine particles remain inside the crystal grains or at the grain boundaries, and the copper fine crystals are recrystallized by heat, and the crystals become coarse. It works to prevent
Therefore, in a preferred embodiment, the normal mechanical strength is large, the decrease in mechanical strength is small even after heating at a high temperature of about 300 ° C., and features superior to electrolytic copper foil using organic compounds as inclusions. Have.

(Use of electrolytic copper foil)
The electrolytic copper foil of the present invention can be suitably used for a flexible printed wiring board (FPC), a negative electrode current collector for a lithium ion secondary battery, and the like.
As described above, in the case of FPC, low roughness and a certain level of strength are required after casting or heat laminating polyimide.
In the negative electrode current collector for a lithium ion secondary battery, when polyimide is used as the binder, the negative electrode is subjected to heat treatment in order to cure the polyimide. If the copper foil is softened after this heating and its hardness becomes too small, deformation of the copper foil may occur when stress of expansion and contraction of the active material is applied to the copper foil during charging and discharging. In a more significant case, the copper foil may break. Accordingly, the copper foil for the negative electrode current collector needs to have a certain strength or more after heating.
Thus, in either case of a flexible printed wiring board (FPC) and a negative electrode current collector for a lithium ion secondary battery, heating is performed at a temperature of about 300 ° C. for the heating effect of polyimide. Therefore, even if the copper foil is heated at a temperature of about 300 ° C. × 1H, a certain level of strength is required thereafter.

  In the electrolytic copper foil of this invention, the standard of the pass level of these mechanical characteristics is as follows in each item. The tensile strength in the normal state is TS ≧ 500 MPa, the 0.2% proof stress is YS ≧ 300 MPa, and the elongation is El ≧ 2%. The tensile strength after heating at 180 ° C. is TS ≧ 310 MPa, the 0.2% proof stress is YS ≧ 200 MPa, and the elongation is El ≧ 1.5%. The tensile strength after heating at 300 ° C. × 1H is TS ≧ 280 MPa, the 0.2% proof stress is YS ≧ 150 MPa, and the elongation is El ≧ 2.5%. The ratio of the tensile strength after heating at 300 ° C. × 1H to the tensile strength in the normal state is 60% or more.

EXAMPLES Hereinafter, although this invention is demonstrated concretely using an Example and a comparative example, this invention is not limited to this.
[Example 1: No organic additive]
The following bath was used as the basic bath composition as the sulfuric acid-copper sulfate electrolyte.
Cu = 50 to 150 g / L
H ₂ SO ₄ = 20 to 200 g / L

An aqueous solution in which sodium tungstate was dissolved in the following amount as an additive A1 was prepared, and this aqueous solution was added to the electrolytic solution having the above basic bath composition to obtain an electrolytic solution 1.
Sodium tungstate = 1 mg / L to 500 mg / L (as tungsten)
The above-mentioned amount means “sodium tungstate in an amount corresponding to 1 mg / L to 500 mg / L as tungsten metal” (the same applies hereinafter).
In Table 2 to be described later, as Example 1, cases where sodium tungstate as additive A1 was added at the following seven levels of addition amounts are shown as Examples 1-1 to 1-7.
Example 1-1 Sodium tungstate = 260 mg / L (as tungsten)
Example 1-2 Sodium tungstate = 150 mg / L (as tungsten)
Example 1-3 Sodium tungstate = 100 mg / L (as tungsten)
Example 1-4 Sodium tungstate = 50 mg / L (as tungsten)
Example 1-5 Sodium tungstate = 30 mg / L (as tungsten)
Example 1-6 Sodium tungstate = 20 mg / L (as tungsten)
Example 1-7 Sodium tungstate = 10 mg / L (as tungsten)
In all cases, the chloride ion concentration was 0 mg / L (not added at all).

Electrodeposition was performed under the following conditions using any one of these electrolytic solutions 1 having different tungsten concentrations, and tungsten-containing electrolytic copper foils each having a thickness of 12 μm were produced.
Current density = 30-100 A / dm ²
Temperature = 30-70 ° C

  Surface roughness of the rough surface (M surface) of each obtained electrolytic copper foil, its tensile strength (TS), 0.2% proof stress (YS) and elongation (El), 180 ° C. × 1H heating Later tensile strength, 0.2% yield strength and elongation, and tensile strength, 0.2% yield strength and elongation after heating at 300 ° C. × 1H, and W content in the copper foil were measured. These results are shown in Table 2.

Here, the surface roughness of the rough surface (M surface) was measured based on JIS B0601-1994, and displayed as Ra (arithmetic average roughness) and Rz (ten-point average roughness).
The tensile strength, 0.2% proof stress, and elongation (breaking elongation) were measured based on JIS Z2241-1880.

About W content in copper foil, after melt | dissolving electrolytic copper alloy foil of a fixed mass with an acid, W in solution is analyzed by ICP emission spectroscopy analysis, W amount contained in electrolytic copper alloy foil Asked. The results are shown in Table 2 as the W content (ppm).
The standard of the pass level of the mechanical characteristic of the copper foil in a present Example is as follows about each measurement item. The rough surface roughness (M surface roughness) is Ra ≦ 0.5 μm and Rz ≦ 2.5 μm. The tensile strength in the normal state is TS ≧ 500 MPa, the 0.2% proof stress is YS ≧ 300 MPa, and the elongation is El ≧ 2%. The tensile strength after heating at 180 ° C. is TS ≧ 310 MPa, the 0.2% proof stress is YS ≧ 200 MPa, and the elongation is El ≧ 1.5%. The tensile strength after heating at 300 ° C. × 1H is TS ≧ 280 MPa, the 0.2% proof stress is YS ≧ 150 MPa, and the elongation is El ≧ 2.5%. The ratio (%) of the tensile strength after heating at 300 ° C. × 1 H to the normal tensile strength is 50% or more.

[Example 2: ammonium tungstate]
The following bath was used as the basic bath composition as the sulfuric acid-copper sulfate electrolyte.
Cu = 80-120 g / L
H ₂ SO ₄ = 80 to 120 g / L

As an additive A2, an aqueous solution in which ammonium tungstate was dissolved in the following addition amount was prepared, and this aqueous solution was added to the electrolytic solution having the above basic bath composition to obtain an electrolytic solution 2.
Example 2 Ammonium tungstate = 150 mg / L (as tungsten)
The chloride ion concentration was 0 mg / L (not added at all).

Using this electrolytic solution 2, electrolytic deposition was performed under the following conditions to produce a tungsten-containing electrolytic copper foil having a thickness of 12 μm.
Current density = 50-100 A / dm ²
Temperature = 50-70 ° C

  Surface roughness of the rough surface (M surface) of the obtained electrolytic copper foil, tensile strength in its normal state, 0.2% proof stress and elongation, tensile strength after heating at 180 ° C. × 1H, 0.2% Yield strength and elongation, tensile strength after heating at 300 ° C. × 1H, 0.2% proof strength and elongation, and contained W amount were measured, respectively. These results are shown in Table 2.

[Example 3: Potassium tungstate]
The following bath was used as the basic bath composition as the sulfuric acid-copper sulfate electrolyte.
Cu = 80-120 g / L
H ₂ SO ₄ = 80 to 120 g / L
As an additive A3, an aqueous solution in which potassium tungstate was dissolved in the following addition amount was prepared, and this aqueous solution was added to the electrolytic solution having the above basic bath composition to obtain an electrolytic solution 3.
Example 3 Potassium tungstate = 150 mg / L (as tungsten)
The chloride ion concentration was 0 mg / L (not added at all).

Using this electrolytic solution 3, electrolytic deposition was performed under the following conditions to produce a tungsten-containing electrolytic copper foil having a thickness of 12 μm.
Current density = 50-100 A / dm ²
Temperature = 50-70 ° C

  Surface roughness of the rough surface (M surface) of the obtained electrolytic copper foil, tensile strength in its normal state, 0.2% proof stress and elongation, tensile strength after heating at 180 ° C. × 1H, 0.2% Yield strength and elongation, tensile strength after heating at 300 ° C. × 1H, 0.2% proof strength and elongation, and contained W amount were measured, respectively. These results are shown in Table 2.

[Comparative Example 1]
An electrolytic copper foil having a thickness of 12 μm and a W content of 5 ppm was produced in the same manner as in Example 1, except that the amount of W added was changed to a low concentration of sodium tungstate = 3 mg / L (as tungsten).
Surface roughness of the rough surface (M surface) of the obtained electrolytic copper foil, tensile strength in its normal state, 0.2% proof stress and elongation, tensile strength after heating at 180 ° C. × 1H, 0.2% Yield strength and elongation, tensile strength after heating at 300 ° C. × 1H, 0.2% proof strength and elongation, and contained W amount were measured, respectively. These results are shown in Table 2. In the table, the tensile strength may be expressed as tensile strength.

[Comparative Example 2]
The following bath was used as the basic bath composition as the sulfuric acid-copper sulfate electrolyte, and no additives were added.
Cu = 80-120 g / L
H ₂ SO ₄ = 80 to 120 g / L

Using this electrolytic solution, electrolytic deposition was performed under the following conditions to produce an electrolytic copper foil having a thickness of 12 μm.
Current density = 50-100 A / dm ²
Temperature = 50-70 ° C

  Surface roughness of the rough surface (M surface) of the obtained electrolytic copper foil, tensile strength in its normal state, 0.2% proof stress and elongation, tensile strength after heating at 180 ° C. × 1H, 0.2% Yield strength and elongation, tensile strength after heating at 300 ° C. × 1H, 0.2% proof strength and elongation, and contained W amount were measured, respectively. These results are shown in Table 2.

[Comparative Example 3]
The following bath was used as the basic bath composition as the sulfuric acid-copper sulfate electrolyte.
Cu = 80-120 g / L
H ₂ SO ₄ = 80 to 120 g / L
An electrolyte solution was obtained by adding the following amounts of sodium tungstate as additive A1 and hydrochloric acid as additive B to the basic bath.
Sodium tungstate = 10 mg / L to 100 mg / L (as tungsten)
Chloride ion (Cl ⁻ ) = 20 mg / L to 100 mg / L

Using this electrolytic solution, electrolytic deposition was performed under the following conditions to produce an electrolytic copper foil having a thickness of 12 μm.
Current density = 50-100 A / dm ²
Temperature = 50-70 ° C

  Surface roughness of the rough surface (M surface) of the obtained electrolytic copper foil, tensile strength in its normal state, 0.2% proof stress and elongation, tensile strength after heating at 180 ° C. × 1H, 0.2% Yield strength and elongation, tensile strength after heating at 300 ° C. × 1H, 0.2% proof strength and elongation, and contained W amount were measured, respectively. These results are shown in Table 2.

[Comparative Example 4]
The following bath was used as the basic bath composition as the sulfuric acid-copper sulfate electrolyte.
Cu = 80-120 g / L
H ₂ SO ₄ = 80 to 120 g / L
To the basic bath, sodium tungstate as additive A1, hydrochloric acid as additive B, and glue as additive C were added in the following amounts to obtain an electrolyte solution.
Sodium tungstate = 10 mg / L to 100 mg / L (as tungsten)
Chloride ion (Cl ⁻ ) = 20 mg / L to 100 mg / L
Nika = 2-10mg / L

Using this electrolytic solution, electrolytic deposition was performed under the following conditions to produce an electrolytic copper foil having a thickness of 12 μm.
Current density = 50-100 A / dm ²
Temperature = 50-70 ° C

  Surface roughness of the rough surface (M surface) of the obtained electrolytic copper foil, tensile strength in its normal state, 0.2% proof stress and elongation, tensile strength after heating at 180 ° C. × 1H, 0.2% Yield strength and elongation, tensile strength after heating at 300 ° C. × 1H, 0.2% proof strength and elongation, and contained W amount were measured, respectively. These results are shown in Table 2.

The tungsten-containing electrolytic copper foils of Examples 1-1 to 1-7 and Examples 2 and 3 have a sufficiently small surface roughness and high mechanical strength in a normal state, even after heating at 180 ° C. × 1H. Even after heating at 300 ° C. × 1 H, the mechanical strength is small and, for example, a tensile strength of 300 MPa or more is maintained.
In addition, when the content of tungsten is 500 ppm or less, there is a tendency for the mechanical strength to decrease in proportion to the decrease in the content. However, as is clear from Example 1-7, the tungsten content is 10 ppm or more. If so, for example, the tensile strength in a normal state is 500 MPa or more.

  The electrolytic copper foil containing 5 ppm of tungsten of Comparative Example 1 has almost the same mechanical characteristics as the electrolytic copper foil of Comparative Example 2 containing no tungsten at all. When the content of tungsten was too small, the effect of adding tungsten was low, resulting in inferior mechanical properties as compared to the examples.

The electrolytic copper foil in which tungsten and chloride ions exceeding 3 mg / L were added to the electrolytic solution of Comparative Example 3 lacked the mechanical strength in the normal state, and further, the mechanical strength decreased after heating at 300 ° C. × 1H. doing. Moreover, as a result of measuring the amount of W in this copper foil, it was below a detection lower limit (1 ppm (= 0.0001 mass%)).
It can be seen that the precipitation of tungsten was suppressed when chloride ions were included in the electrolyte.

Comparative Example 4 was prepared based on Patent Document 1 (Japanese Patent No. 3238278), and was prepared with a composition in which glue was further added to the electrolytic solution of Comparative Example 3.
The surface roughness of the rough surface was rough, the mechanical strength in the normal state was small, and the mechanical strength decreased after heating at 300 ° C. × 1H. Moreover, when the amount of W in this copper foil was measured, it was below the lower limit of detection.
When chloride ions are contained in the electrolyte solution in an amount exceeding 3 mg / L, electrolytic deposition of a metal that hardly forms an alloy with copper, such as tungsten, is suppressed. For example, rough precipitation based on the addition effect of organic additives such as glue. It was confirmed that an electrolytic copper foil having a rough surface was formed, but an electrolytic copper alloy foil was not formed.
As described above, in the course of the study leading to the present invention, the present inventors made tungsten oxide changed from a tungsten salt present in the sulfuric acid-copper sulfate electrolyte, and further increased the chloride ion to a concentration exceeding 3 mg / L. When contained at a concentration, it was confirmed that tungsten was not eutectoid in the electrolytically deposited copper.

[Examples 11 to 21: Use of W, Mo, Ti, Te]
In Examples 11 to 21 and Comparative Example 11, the following baths were used as basic bath compositions as sulfuric acid-copper sulfate based electrolytes.
Cu = 80-120 g / L
H ₂ SO ₄ = 80 to 120 g / L
An aqueous solution in which various metal salt compounds (various metal sources) listed in Table 3 and sodium chloride (chloride ion source) are dissolved as additives is added to the basic bath, and the metal salt concentration as shown in Table 3 is added. And an electrolytic solution was obtained by adjusting the chloride ion concentration.
Electrodeposition was performed using any one of these various electrolytic solutions under the following conditions to produce electrolytic copper foils each having a thickness of 12 μm.
Current density = 50-100 A / dm ²
Temperature = 50-70 ° C

The comparative example 12 was created as follows based on patent document 2 (Unexamined-Japanese-Patent No. 2000-17476). _{CuSO 4 · 5H 2 O, H} 2 SO 4, and the electrolyte containing SnSO ₄ by bubbling treatment with _{air, CuSO 4 · 5H 2 0 =} 250g / L, H 2 SO 4 = 50g / L, SnO 2 An electrolyte solution comprising fine particles and ultrafine particles = 3 g / L, SnSO ₄ = 10 g / L, and polyethylene glycol = 0.001 to 0.1 g / L as a polyether was prepared. Using this electrolytic solution, electrolytic deposition was performed under the conditions of current density = 10 A / dm ² and bath temperature = 50 ° C. to produce an electrolytic copper foil having a thickness of 12 μm.

Comparative Example 13 was created as follows based on Patent Document 3 (Japanese Patent No. 3934214). An electrolytic solution in which 50 ppm of silver ions were added to a sulfuric acid acidic copper sulfate solution having a copper ion concentration of 70 to 120 g / L and a sulfate ion concentration of 50 to 120 g / L was used. Using this electrolytic solution, electrolytic deposition was performed under the conditions of current density = 120 A / dm ² and electrolytic solution concentration = 57 ° C. to produce an electrolytic copper foil having a thickness of 12 μm.

  As a reference example, a commercially available Cu-0.015 to 0.03 Zr rolled copper alloy foil (trade name: HCL-02Z, manufactured by Hitachi Cable, Ltd.) having a thickness of 12 μm was used.

  About the obtained electrolytic copper foil of each Example and comparative example, and the rolled copper alloy foil of the reference example, the tensile strength (TS) in the normal state, the tensile strength after heating at 300 ° C. × 1H, the ratio thereof, the conductivity The rate (EC), chlorine content, and metal content were measured as follows.

  The tensile strength was measured based on JIS Z2241-1880. The value of the tensile strength in the normal state of the copper foil was judged to be good when it was 500 MPa or more and poor when it was less than 500 MPa. Further, as a condition in a more preferable aspect, the ratio of the tensile strength value after heat treatment of the copper foil at 300 ° C. for 1 hour (300 ° C. × 1 H) to the normal tensile strength value is 80% or more. , Less than 80% was judged as defective.

  The conductivity was measured by a four-terminal method (current / voltage method) based on JIS K6271. The electrical conductivity of the copper foil was judged to be 65% IACS or better, 50% IACS or better to be good, and less than 50% IACS to be bad.

Regarding the contents of metals such as W and Cl in copper foil and after dissolving a certain mass of electrolytic copper foil with acid, the amount of metals such as W in the resulting solution should be analyzed by ICP emission spectroscopy. I asked for it. Further, the chlorine content in the obtained solution was determined by a silver chloride titration method (detection limit: 1 ppm).
These results are shown in Table 3.

  Examples 11 to 17 are tungsten (W) oxide fine particles and ultrafine particles as metal oxides, Examples 18 and 21 are molybdenum (Mo) oxide fine particles and ultrafine particles, and Example 19 is titanium (Ti). ) Oxide fine particles and ultrafine particles, and in Example 20, oxide fine particles and ultrafine particles of tellurium (Te) are each incorporated into an electrolytic copper foil, and the content thereof is 10 to 2610 ppm in terms of each metal. Is in range. Therefore, it has a high normal tensile strength of 500 MPa or more, and the retention rate of tensile strength after heating at 300 ° C. × 1 H is also 50% or more. The conductivity is also 55% or more.

  In particular, Examples 11 to 14, 18, 19, and 20 have a metal element content in the range of 100 to 2500 ppm. Therefore, it has a high normal tensile strength of 500 MPa or more, and the maintenance ratio of the tensile strength after heating at 300 ° C. × 1H exceeds 80%. The conductivity is as high as 65% or more.

  In particular, in Examples 11 to 14 and 17 containing tungsten, the content of tungsten is 280 to 2460 ppm, it has a high normal tensile strength of 600 MPa or more, and the tensile strength after heating at 300 ° C. × 1 H The maintenance rate is also over 80%. The conductivity is as high as 65% or more. The same applies to Examples 1-1 to 1-5, 2, and 3.

  In Example 16, tungsten oxide fine particles and ultrafine particles were incorporated in Example 21, and molybdenum oxide fine particles and ultrafine particles were incorporated in less than 100 ppm each, and the content thereof was low. Therefore, the tensile strength in the normal state was sufficiently high, but the tensile strength after heating at 300 ° C. × 1H was lowered.

  In Example 15, the amount of tungsten oxide fine particles and ultrafine particles taken in exceeded 2500 ppm. Therefore, although the improvement effect of tensile strength and heat resistance was seen, the electrical conductivity was lower than 65%.

Example 17 is a case where the chloride ion content in the electrolytic solution was 3 ppm. Chlorine was not detected in the electrolytic copper foil, and the results were comparable to Examples 11-14.
In addition, Example 13 is a test example in which the metal (W) content is different from that of Example 1-1. In any case, since the metal content is large, the effect of the inclusions contained is saturated, and the experimental results are considered to be similar in the two test examples.

Moreover, the amount of chlorine in the electrolytic copper foil was measured by SIMS (Secondary Ion Mass Spectrometry) analysis. The measurement conditions of the SIMS analysis were as follows: primary ion: Cs ⁺ (5 kV, 100 nA), secondary (detection) ion: copper (Cu) ⁶³ Cu− · chlorine (Cl) ³⁵ Cl−, sputtering region: 200 μm × 400 μm. . Since the surface of the electrolytic copper foil was affected by dirt and oxide film, the measurement was started after sputter removal from the surface to the depth direction of 2 μm, and the analysis was performed to the depth of 4 μm. As a result of calculating the strength ratio from the average value of the strength of each measurement element and the average value of the strength of copper and comparing it with the standard sample, the chlorine content in the electrolytic copper foil of each example is less than 1 ppm. It was confirmed. It is speculated that the low chlorine content increases the amount of tungsten and contributes to improved heat resistance.

  Comparative Example 11 contains 2 ppm of chlorine in the electrolytic copper foil. Therefore, the content of oxide fine particles and ultrafine particles of tungsten (W) in the electrolytic copper foil was small, and the tensile strength was also lower than those of Examples 11-21.

  Comparative Example 12 contains 6 ppm of chlorine in the electrolytic copper foil. Therefore, tungsten (W) was not detected in the electrolytic copper foil. The tensile strength also became a low value compared with Examples 11-21.

Comparative Example 13 is a test example created based on Patent Document 2 (Japanese Patent Laid-Open No. 2000-17476). Cu-Sn is well known as a rolled alloy. In the electrolytic copper foil of Comparative Example 13, no superiority is recognized even when various characteristic values and manufacturing costs are compared with the Cu—Sn rolled alloy. Further, tin sulfate (SnSO ₄ ), which is not an oxide in the sulfuric acid electrolytic solution, is forcibly oxidized by oxygen bubbling to form SnO ₂ fine particles and ultrafine particles. The particle diameter of the oxide produced therein and taken into the copper foil was more than 20 nm, and the conductivity was low because the particle diameter was larger than particles such as tungsten.

  Comparative Example 14 is a test example created based on Patent Document 3 (Japanese Patent No. 3934214). In the electrolytic copper foil of Comparative Example 14, Ag is dissolved as Cu and taken in as metal Ag. Therefore, the ratio of the tensile strength after heating at 300 ° C. × 1 H to the normal tensile strength (%) compared to the examples of the present invention in which the metal is taken in as oxide fine particles or ultrafine particles and strengthened by precipitation. ) Was inferior.

  A reference example is Cu-0.015-0.03Zr rolled copper alloy foil. It can be seen that the electrolytic copper foil of the present invention has mechanical properties and electrical conductivity equal to or higher than those of the rolled copper alloy foil.

[Examples 31 to 38: Use of thiourea organic material]
In Examples 31-38, the following baths were used as basic bath compositions as sulfuric acid-copper sulfate electrolytes.
CuSO ₄ = 200 to 500 g / L
H ₂ SO ₄ = 80 to 120 g / L
NaCl = 0-55 mg / L
To the basic bath, add various metal salt compounds (various metal sources) listed in Table 3 and aqueous solutions in which organic components are dissolved as additives to adjust the metal salt concentration and organic concentration as shown in Table 3. An electrolytic solution was obtained. In addition, the density | concentration of a metal salt compound represents the density | concentration contained as a metal.
Electrodeposition was performed using any one of these various electrolytic solutions under the following conditions to produce electrolytic copper foils each having a thickness of 12 μm.
Current density = 30-100 A / dm ²
Temperature = 30-75 ° C

  About the obtained electrolytic copper foil of each Example, the tensile strength (TS) in a normal state, the tensile strength measured at normal temperature after the 300 degreeC x 1H heating, those ratio, metal content, other Examples Measured in the same manner as above. These results are shown in Table 3.

  In Examples 31 to 35, only the organic component was added. In Examples 31-35, although the metal is not contained in the electrolytic copper foil, the organic component is contained as inclusions, and thus has a high tensile strength exceeding 700 MPa in a normal state. However, since the inclusion was an organic component, the tensile strength retention rate measured at room temperature after heating at 300 ° C. for 1 hour was lower than in Examples 36 to 38 containing metal fine particles.

  In Examples 36-38, both the metal salt compound and the organic component were added. In Examples 36 to 38, the electrolytic copper foil contains 98 to 280 ppm of metal and has inclusions with a particle size of 5.8 to 6.1, and thus has a high tensile strength exceeding 700 MPa in a normal state. ing. Further, since the inclusion was a metal oxide, the tensile strength retention rate measured at room temperature after heating at 300 ° C. for 1 hour was high.

  In Example 38, tungsten oxide fine particles and ultrafine particles are incorporated in less than 100 ppm, and the content thereof is low. Therefore, although the tensile strength in the normal state was sufficiently high, the tensile strength measured at room temperature after heating at 300 ° C. × 1 H was lowered.

  Moreover, according to the measurement result of the average particle diameter of the inclusions described later, in the example in which only the metal salt compound was added, the average particle diameter of the inclusions was about 1 nm. However, in Examples 31-35, it was found that the average particle diameter of inclusions derived from organic components exceeded 10 nm and had a relatively large particle diameter. Moreover, since Examples 36-38 contained both metal oxide microparticles | fine-particles etc. and the inclusion derived from an organic substance component, the average particle diameter was about 5 nm.

(SIM observation of crystal grains)
Moreover, when the electrolytic copper foil which concerns on each Example was observed by SIM (scanning ion microscopy), in any electrolytic copper foil, the average particle diameter of a copper crystal grain is 100-600 nm, and a copper crystal grain Was found to have a substantially spherical shape with an aspect ratio of the major axis to the minor axis of about 0.5 to 2.0.

[TEM observation]
In order to confirm containing inclusions, TEM (Transmission Electron Microscopy, Transmission Electron Microscope) observation was performed on the copper foil sample (Example 1-1) to which W was added. The TEM sample was prepared by using an FIB (Focused Ion Beam) method in which the acceleration voltage of the Ga ion beam was 30 kV. Thereafter, irradiation with a 1 kV Ar ion beam was performed for 30 minutes while cooling with liquid nitrogen in order to remove damage on the sample surface by FIB. The result of the TEM observation of the copper foil before firing is shown in FIG. An underfocus image was taken using TOPBF manufactured by TOPCON. The focus value is changed by −300 nm from the just focus position. When observed with under focus, Fresnel fringes are formed due to the influence of the edge of the inclusion, and the inclusion is emphasized and observed. Since it is not just focus, it is observed larger than the original size of inclusions, but many inclusions with a size of several nm are observed. Inclusions indicated by arrows are observed relatively large.

  In FIG. 3, the TEM image of the copper foil which baked the copper foil which concerns on Example 1-1 at 300 degreeC is shown. 3 is an underfocus image under the same conditions as in FIG. Compared with the copper foil before firing, inclusions are greatly observed. Inclusions indicated by arrows in the figure are observed relatively large. Inclusions are considered to aggregate by firing, but such large inclusions exhibit a stronger pinning effect, and are therefore desirable as a high strength and high resistance copper foil.

  FIG. 4 shows a high-resolution STEM image. Here, a high angle annular dark field scanning scanning electron microscope (HAADF-STEM, high-angle annular dark field scanning transmission electron microscope) image was obtained using an aberration correction STEM2100F manufactured by JEOL. Inclusions formed of W atoms having different contrasts are observed in the lattice image of Cu. This size is 1-2 nm.

  FIG. 5 shows a HAADF-STEM image of a copper foil containing both ethylenethiourea and tungsten. Here, inclusions are observed in crystal grains having a size of several to 10 nm and in crystal interfaces. Inclusions present at the crystal interface act as a pinning force to prevent the crystal grains from growing, and inclusions in the crystal grains can be pinned even if the crystal is enlarged due to firing. Prevents further crystal enlargement by acting as a force.

  Although the TEM image of the copper foil which does not contain W in FIG. 6 is shown, the inclusion is not observed. Although observed in many fields of view, the inclusions as shown in FIGS. 2, 3, 4, and 5 could not be observed. From this fact, it is understood that inclusions in the copper foil, which is an embodiment of the present invention, can be successfully formed by adding a metal such as W.

[Small angle X-ray scattering measurement]
Small-angle X-ray scattering is a method for directly measuring the size and shape of an object of 1 nm to 1 μm in a bulk sample, and the distribution and fluctuation of nanoscale atoms and molecules. If this measurement method is used, the average particle diameter, size distribution, and number density of the fine particles shown by TEM observation can be obtained.

  A copper foil sample added with W (Example 1-1), a copper foil sample added with Mo (Example 18), and a copper foil sample added with W and TU (thiourea) (Example 36) SAXS (small) Angle X-ray scattering (small angle X-ray scattering) and USAXS (ultra small angle X-ray scattering) were performed. The SAXS (USAXS) measurement was performed at the industrial use beam line BL19B2 of Spring-8 (super photo ring 8GeV, high-intensity synchrotron radiation facility).

  FIG. 7A shows a simple optical axis diagram of SAXS (USAXS) measurement. Incident X-rays 14 generated from the X-ray source 13 including the shutter 15 are irradiated to the sample 27 through the monochromator 17, the first pinhole 19, the second pinhole 21, and the third pinhole 25. From incident X-rays 14 irradiated on the sample 27, transmitted X-rays 29 that pass through the sample 27 and scattered X-rays 31 scattered by the sample 27 are generated. The detector 35 is provided at the end of the optical axis and detects transmitted X-rays 29 or scattered X-rays 31.

  When the scattered X-ray 31 is measured by the detector 35, the incident X-ray 14 is irradiated to the sample 27 without passing through the attenuator 23 and the transmitted X-ray 29 is irradiated by the beam stopper 33 as shown in FIG. The light is shielded and the scattered X-ray 31 is measured by the detector 35.

  When measuring the transmitted X-ray 29 with the detector 35, as shown in FIG. 7C, the intensity of the incident X-ray 14 is weakened with the attenuator 23, and then the sample 27 is irradiated with the incident X-ray 14. The transmitted X-ray 29 is measured by the detector 35 without shielding the transmitted X-ray 29 by the beam stopper 33.

Let L be the distance from the sample 27 to the detector 35. A location where the transmitted X-ray 29 transmitted through the sample 27 reaches the detector 35 is denoted by O, and a location where the scattered X-ray 31 scattered from the sample 27 at the angle θ reaches the detector 35 is denoted by A. If AO = r, then tan θ = r / L and θ can be obtained. Hereinafter, the horizontal axis of the SAXS and USAXS data is described as q (nm ⁻¹ ) expressed by the equation (4).
q = 4πsin θ / λ (4)

λ is the wavelength of incident X-rays. In the measurement, λ = 0.068 nm, the distance from the sample to the detector was L = 4.2 m (SAXS), and L = 42 m (USAXS). The range of measurement is q = 0.05-4 (nm < ^-1 >). The detector used was a semiconductor two-dimensional detector Pilatus. After performing SAXS measurement, it was confirmed that there was no anisotropy by looking at the mapping of the intensity of two-dimensional X-rays, and one-dimensionalization was performed. 8A is a view showing an electrolytic copper foil containing W, FIG. 8B is a view showing an electrolytic copper foil containing Mo, and FIG. 8C is an electrolytic copper foil containing W + TU (thiourea). In the figure, A shows after firing, B in the figure before firing, and C in the figure shows pure copper foil. The vertical axis shows X-ray intensity, and the horizontal axis shows SAXS data with q. As can be seen from the figure, the pure copper foil and the electrolytic copper foil are compared, and the intensity of the X-ray is different between q = 0.4-2. This suggests that inclusions of 10 nm or less are present in the electrolytic copper foil.

Φ_０はダイレクトビームの強度、ηは検出器による補正項、Ｓは照射面積、Ｔは透過率、Ｄは厚さである。基本的にはΦ_０、η、Ｓは一定なのでΦ_０・η・Ｓ＝Ａ＝ｃｏｎｓｔとして装置固有の値とする。Regarding the W-containing electrolytic copper foil, the fine particles are considered to be WO ₃ from the results of TEM observation and XAFS measurement. In FIG. 9, X-ray scattering from WO ₃ is extracted by subtracting the SAXS intensity of the pure copper foil from the SAXS data of the W-containing electrolytic copper foil. In the figure, D indicates pure copper before firing, E in the figure indicates before firing, and F in the figure indicates pure copper. Using this extracted data, in order to calculate the number density of WO ₃ , the scattering cross section was obtained from the scattered X-rays, and fitting was performed. The measured X-ray scattering intensity I (q) and the scattering cross section dΣ / dΩ (q) are in the relationship of equation (5).

Φ ₀ is the intensity of the direct beam, η is the correction term by the detector, S is the irradiation area, T is the transmittance, and D is the thickness. Since Φ ₀ , η, and S are basically constant, Φ ₀ · η · S = A = const is a value unique to the apparatus.

一方で散乱断面積は式−（７）で表される。

ｄΣ／ｄΩ（ｑ）は散乱断面積、Δρ２は原子散乱因子、ｄＮは粒子数密度、Ｖは粒子体積、Ｆは粒子の形状因子、Ｎ（ｒ）は粒径分布関数である。ＴＥＭ観察の結果から、粒子の形状因子は球体とした（式−（８））。

散乱Ｘ線強度から求めた散乱断面積：ｄΣ／ｄΩ（ｑ）を変数ｑで式−（６）を用いてフィッティングを行った。その結果、Ｗ入り電解銅箔に含まれる介在物は、図１０（ａ）に示すように平均粒子径（半径）は０．８ｎｍ程度であり、平均粒子径（直径）は１．６ｎｍ程度であることがわかった。粒子の分布は半径０．８ｎｍを中心として図１０（ｂ）に示すような分布（体積分布ｆ（Ｒ））を取る。なお、図中Ｄは、焼成前の純銅を示し、図中Ｇは、球体モデルを示す。Regarding A, glassy carbon measured with an apparatus in which Φ ₀ , η, and S had been determined in advance was also measured with SPring-8, BL19B2, and A was calculated. Symbols S, C, and N in the formula (5) are abbreviations of Sample, Cell, and Noise, respectively. In this application, Sample is an electrolytic copper alloy foil, and Cell is a pure copper foil. When the scattering cross section is obtained from Equation- (5), Equation- (6) is obtained.

On the other hand, the scattering cross section is expressed by the formula-(7).

dΣ / dΩ (q) is a scattering cross section, Δρ2 is an atomic scattering factor, dN is a particle number density, V is a particle volume, F is a particle shape factor, and N (r) is a particle size distribution function. From the result of TEM observation, the shape factor of the particle was a sphere (formula- (8)).

Fitting was performed using a scattering cross section dΣ / dΩ (q) obtained from the scattered X-ray intensity and a variable q, using equation-(6). As a result, the inclusions contained in the W-containing electrolytic copper foil have an average particle diameter (radius) of about 0.8 nm and an average particle diameter (diameter) of about 1.6 nm as shown in FIG. I found out. The particle distribution takes a distribution (volume distribution f (R)) as shown in FIG. In the figure, D indicates pure copper before firing, and G in the figure indicates a spherical model.

  The same measurement was performed for each of the examples and comparative examples, and the average particle diameter (diameter) of inclusions contained in the electrolytic copper foil was measured.

Moreover, the number density of the particles of WO ₃ contained in the electrolytic copper foil according to Example 1-1 containing about 1900 ppm of W is 3.0 × 10 ¹⁸ particles / cm ³ by making the strength an absolute value. I understood it. From this fact, it was confirmed that by adding a metal such as W, it was possible to successfully form inclusions of a desired size and number density in the copper foil according to the embodiment of the present invention.

[XAFS measurement]
As one of the analysis methods using X-rays, XAFS (analysis of chemical bonding state and electronic state in a sample is performed from the obtained X-ray absorption spectrum by irradiating the sample with X-rays while changing X-ray energy. X-ray fine absorption structure (X-ray absorption structure) method is known. X-ray absorption spectrum is obtained by a transmission method for obtaining the X-ray absorption spectrum from the intensity of the incident X-ray and the intensity of the transmitted X-ray, and the intensity of the fluorescent X-ray emitted from the sample accompanying the X-ray absorption is measured. There is a fluorescence method.

  When an additive element such as a metal material is to be analyzed, the amount of addition is very small, and it is difficult to obtain an XAFS spectrum by the transmission method. The fluorescent method described above is effective in such a case. A feature of the fluorescence method is that XAFS measurement is possible even with a trace amount of elements by taking a wider X-ray irradiation area than the optical axis system.

  The purpose of this measurement is to know the chemical bonding state and electronic state of W and Mo in the high-strength copper foil. The amount of W and Mo in the copper foil is very small, and it is difficult to obtain the XAFS spectrum by the transmission method. Because of this, the fluorescence method was selected. Regarding the measurement, SPring-8 industrial use beam line BL14B2 was used. The measured X-ray energy ranges are 10,000 to 10434 eV and 19960 to 20600 eV. The L3 absorption edge (10207 eV) of W exists in the former energy range, and the K-absorption edge (20000 eV) of M exists in the latter energy range.

Except for containing 250 mg / L of sodium tungstate (IV) (metal equivalent) and 20 mg / L of sodium molybdate (IV) in the same manner as in Example 11,
A copper foil containing 2500 ppm of W and 200 ppm of Mo was prepared and used for measurement. For comparison, W foil, WO ₃ , Mo foil, and MoO ₃ were prepared. As a result, it was found that W in the electrolytic copper foil was in an oxide state and was WO ₃ (FIG. 11 (a)). Further, it was found that Mo is in an oxidized state and is MoO ₃ (FIG. 11 (b)). In the figure, H is W foil, I is WO _{3 in} the figure, J is copper foil, K is Mo foil in the figure, and L is MoO _{3 in the} figure.

As described above, the electrolytic copper foil according to the embodiment, prior to the heat treatment 300 ° C. × IH, it can be seen that including WO ₃ or particulate inclusions MoO ₃ having an average particle diameter of 0.8 nm.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the technical idea disclosed in the present application, and these are naturally within the technical scope of the present invention. Understood.

DESCRIPTION OF SYMBOLS 1 ......... Electrolytic copper foil 3 ......... Crystal grain 5 ......... Inclusion 13 ......... X-ray source 14 ...... Incident X-ray 15 ......... Shutter 17 ......... Monochromator 19 ......... 1st Pinhole 21 ......... Second pinhole 23 ......... Attenuator 25 ......... Third pinhole 27 ......... Sample 29 ......... Transmission X-ray 31 ......... scattered X-ray 33 ......... Beam stopper 35 ………Detector

Claims (7)

An electrolytic copper foil having inclusions with an average particle size of 0.5 to 50 nm inside the copper crystal grains or at the grain boundaries between the copper crystal grains,
The inclusion includes an inorganic compound;
The number density of inclusions is 1.0 × ¹⁰ 17 ~1.0 × ^{10 19} atoms / cm ^3,
The inorganic compound includes an oxide of one or more metal elements selected from the group consisting of tungsten, molybdenum, and tellurium;
The electrolytic copper foil, wherein the content of the metal element in the foil is 150 to 2460 ppm.   The electrolytic copper foil according to claim 1, wherein an average grain size of the crystal grains is 100 to 600 nm.   The electrolytic copper foil according to claim 1 or 2, wherein a content of chlorine in the electrolytic copper foil is less than 1 ppm. A current collector made of the electrolytic copper foil according to any one of claims 1 to 3,
An electrode active material layer having an electrode active material formed on the surface of the current collector;
An electrode for a non-aqueous electrolyte secondary battery, comprising:   A nonaqueous electrolyte secondary battery using the electrode for a nonaqueous electrolyte secondary battery according to claim 4. An aqueous solution containing an inorganic compound is added to a sulfuric acid-copper sulfate electrolyte containing sulfuric acid and copper sulfate,
Electrolytic deposition using the electrolytic solution to produce an electrolytic copper foil,
The number density of the precipitates is 1.0 × 10 ^{17 to} 1.0 × 10 ¹⁹ pieces / cm ³ ,
The aqueous solution containing the inorganic compound is an aqueous solution in which a salt of one or more metal elements selected from the group consisting of tungsten, molybdenum, and tellurium is dissolved,
Content of the metallic element in foil is 150-2460 ppm, The manufacturing method of the electrolytic copper foil characterized by the above-mentioned. The method for producing an electrolytic copper foil according to claim 6, wherein a chloride ion concentration in the electrolytic solution is less than 3 mg / L.

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