KR101780908B1 - Copper alloy foil - Google Patents

Abstract

The present invention provides a copper alloy foil suitable for use as a negative electrode current collector, an FCCL, and an electromagnetic shielding body of a secondary battery. , Zn and Zr in a total amount of 0.01 to 0.50 mass%, the balance of Cu and impurities, having an electrical conductivity of 80% IACS or more, maintaining a tensile strength of 300 MPa or more after heating at 300 ° C for 30 minutes To a copper alloy foil.

Description

Copper alloy foil {COPPER ALLOY FOIL}

The present invention relates to a copper alloy foil suitable for a negative electrode collector material of a secondary battery including a lithium ion secondary battery (LIB), a conductor material of a flexible copper clad laminate (FCCL), an electromagnetic shield material such as an electric wire covering material, ≪ / RTI >

Copper foil is widely used in electronic and electric devices. Here, a metal plate having a thickness of 0.05 mm or less is used as a foil. Copper foil has rolled copper foil and electrolytic copper foil. The feature of the rolled copper foil for the electrolytic copper foil is that the characteristics such as strength, Young's modulus, fatigue, heat resistance, conductivity, and corrosion resistance can be arbitrarily adjusted by adding alloying elements and adjusting the rolling and heat treatment conditions. Therefore, a rolled copper alloy foil (hereinafter referred to as a copper alloy foil) is often used for applications requiring higher functions.

For example, Japanese Laid-Open Patent Publication No. 2009-097075 (Patent Document 1) discloses a copper alloy foil in which at least two of Sn, Mg, In, and Ag are added to Cu as a copper foil for FCCL to improve heat resistance and bendability have. In order to improve the charge / discharge cycle life of the secondary battery, Japanese Patent Laid-Open Publication No. 2011-216463 (Patent Document 2) discloses a method for manufacturing a secondary battery, which comprises depositing Cu, Ag, Cr, Fe, In, Ni, P, Si, Sn, Te, Ti, Zn, and Zr is added and anisotropy of the Young's modulus is reduced.

Japanese Laid-Open Patent Publication No. 2009-097075 Japanese Laid-Open Patent Publication No. 2011-216463

With the miniaturization and sophistication of electronic and electric devices, there is a growing demand for the characteristics of copper foil. For example, the life span of the charge / discharge cycle in the negative electrode current collector of the secondary battery, the bending life in the FCCL, and the durability in the electromagnetic shielding body can be given. It is an object of the present invention to provide a copper alloy foil capable of coping with these demands.

The present inventors have found that when the copper alloy foil is loaded with stress less than the elastic limit and held for a long time, a minute elongation is generated even at room temperature. It has been found that the use of a copper alloy foil having a small creep elongation (hereinafter referred to as creep) at room temperature improves the functionality of the electronic / electric device.

For example, when the copper alloy foil is coated with a carbonaceous material or the like as an active material, and the LIB is fabricated using the negative electrode collector as the negative electrode collector, the charge / discharge cycle life of the LIB is improved. When the LIB is charged, lithium ions migrate from the positive electrode to the negative electrode, and during discharging, lithium ions migrate from the negative electrode to the positive electrode. Since the negative electrode active material expands and shrinks with the movement of the lithium ion, the copper foil receives mechanical repeated stress by charging and discharging. As a result, the copper foil is permanently deformed, the active material is peeled off, and the battery characteristics are deteriorated. It was thought that the permanent deformation of the copper alloy foil under the repeated stress was reduced in the case of the copper alloy foil having a small creep and the deterioration of the battery characteristics was improved.

Further, when the FCCL was produced using a copper alloy foil having a small creep, the bending life of the flexible printed circuit board (FPC) produced using the FCCL was improved. In the case of a copper alloy foil with a small creep, permanent deformation of the copper alloy foil when the FPC is bent is alleviated, thereby suppressing crack generation and growth of the copper alloy foil.

Similarly, in the case of an electric wire covering material for electromagnetic shielding, if a copper foil with a small creep is used, the damage of the copper alloy foil when the electric wire is repeatedly bent can be seen to be reduced.

Although the creep elongation of the copper alloy foil is extremely small, it is presumed that the above-described influence becomes effective under an environment where repeated stress is applied over a long period of time.

Further, as a result of intensive studies, the present inventor has found that the orientation of crystal grains oriented on the rolled surface of a copper alloy foil affects creep. Specifically, in order to reduce creep, it is effective to increase the (111) plane and the (220) plane on the rolled surface, while the increase of the (200) plane is detrimental. Then, through an experimental examination, a crystal orientation index which is an index of creep was invented, and by controlling this index, it was possible to reduce the creep.

In one aspect of the present invention, the present invention is completed on the basis of the above findings. In one aspect, the present invention provides a method of manufacturing a semiconductor device, comprising at least one of Ag, Cr, Fe, In, Ni, P, Si, Sn, Te, Ti, Zn, By mass and the balance of Cu and impurities and having an electrical conductivity of 80% IACS or more, holding a tensile strength of 300 MPa or more after heating at 300 占 폚 for 30 minutes, and an A value given by the following equation: 0.5 or more Copper alloy foil is provided.

A = 2X ₍₁₁₁₎ + X ₍₂₂₀₎ - X ₍₂₀₀₎

X _(hkl) = I _(hkl) / _{I0 (hkl)}

I _(hkl) and Io _(hkl) are the diffraction integral intensities of (hkl) planes obtained for the rolled surface and copper, respectively, by X-ray diffractometry.

According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising 0.01 to 0.50 mass% of at least one of Ag, Cr, Fe, In, Ni, P, Si, Sn, Te, Ti, Zn, And having an electrical conductivity of 80% IACS or more, holding a tensile strength of 300 MPa or more after heating at 300 占 폚 for 30 minutes, holding a tensile stress of 100 MPa at 30 占 폚 for 100 hours, The copper alloy foil is 0.1% or less.

In the aforementioned copper alloy foil, it is preferable that Zr is contained in an amount of 0.01 to 0.20 mass%, and the balance of Cu and impurities.

In the above-described copper alloy foil, it is preferable that Sn is contained in an amount of 0.01 to 0.20 mass% and the remainder is made of Cu and impurities.

In the copper alloy foil described above, it is preferable that Ag is contained in an amount of 0.05 to 0.50 mass% and the remainder is made of Cu and an impurity.

In the copper alloy foil described above, it is preferable that the copper alloy foil contains 0.05 to 0.50% by mass of Fe and 0.005 to 0.10% by mass of P and the balance of Cu and impurities.

In each of the copper alloy foils described above, the thickness is preferably 0.003 to 0.05 mm.

Each of the copper alloy foils described above can be used as a negative electrode collector of a secondary battery.

From this point of view, the present invention provides, in another aspect, a secondary battery using a negative electrode current collector composed of the above-described copper alloy foil.

Each of the copper alloy foils described above can be used for a flexible copper clad laminate.

In view of this point, the present invention provides, in another aspect thereof, a flexible copper clad laminate composed of the above-described copper alloy foil.

Each of the copper alloy foils described above can be used in an electromagnetic wave shielding body.

From this point of view, the present invention provides, in another aspect, an electromagnetic shielding body composed of the above-described copper alloy foil.

1 is a view for explaining the principle of measurement of creep characteristics.
2 is a schematic view showing the structure of a general secondary battery.

(1) Components of Copper foil

In order to improve the strength and heat resistance of the copper foil of the present invention, at least one of Ag, Cr, Fe, In, Ni, P, Si, Sn, Te, Ti, Zn, To 0.50% by mass. When the total amount of the above elements exceeds 0.50 mass%, the conductivity is lowered, making it unsuitable as a conductive material. When the total amount of the added elements is less than 0.01% by mass, the effect of the contained element is not exhibited and the strength and heat resistance are insufficient.

As the Cu material used as the base, an oxygen-free copper specified in JIS-C1020 or a tough pitch copper specified in JIS-C1100 is suitable. The oxygen concentration of the anaerobic copper melt bath is usually 0.001 mass% or less, and the oxygen concentration of the tough pitch copper molten metal is usually 0.01 to 0.05 mass%.

When at least one element of Cr, Fe, In, Ni, P, Si, Sn, Te, Ti, Zn, and Zr which is more easily oxidized than Cu is employed, these elements form oxides, It is common to add it to anaerobic copper molten metal in order to avoid it.

Since Ag is harder to oxidize than Cu, it can be added to all of the tough pitch copper molten metal and the oxygen free copper molten metal.

The addition amount of Ag, Cr, Fe, In, Ni, P, Si, Sn, Te, Ti, Zn and Zr satisfies the target tensile strength, heat resistance and conductivity described below in the range of 0.01 to 0.50 mass% .

By adding Ag and Te, the strength and heat resistance can be improved without substantially decreasing the electric conductivity.

Sn and In exhibit relatively high effects for improvement of strength and heat resistance, and handling of ingot display is comparatively easy.

Zr, Ti, and Cr are precipitated in Cu to remarkably improve strength and heat resistance. However, since they are very active, it is easy to form oxides and carbides in molten copper. When an oxide or a carbide is produced, the material may be broken or pinholes may be generated during rolling to the foil, so care must be taken for the ingot presentation.

Compounds such as Fe-P, Ni-P, Fe-Si and Ni-Si are precipitated by adding Fe and Ni at the same time as P and Si, and higher strength and heat resistance can be obtained than when they are added singly.

Zn has an effect of improving surface properties such as plating ability and migration resistance although the effect of improving the strength and heat resistance is not so large.

The effects of the present invention are particularly preferably exhibited in the copper alloy foil of the following components.

(a) 0.01 to 0.20 mass% of Zr and the balance of Cu and impurities.

(b) 0.01 to 0.20% by mass of Sn and the balance of Cu and impurities.

(c) 0.05 to 0.50 mass% of Ag, and the balance of Cu and impurities.

(d) a copper alloy foil containing 0.05 to 0.50 mass% of Fe and 0.005 to 0.10 mass% of P, the balance being Cu and an impurity.

(2) Thickness of copper alloy foil

The thickness of the copper alloy foil is preferably 0.003 to 0.05 mm. If the thickness is less than 0.003 mm, handling of the copper alloy foil becomes difficult. If the thickness exceeds 0.05 mm, miniaturization of the electronic parts becomes difficult. A more preferable thickness is 0.005 to 0.02 mm.

(3) creep characteristics

As the creep characteristics, a tensile stress of 100 MPa at 30 캜 was added, and the elongation at the time of holding for 100 hours was evaluated. When the elongation percentage is 0.1% or less, more preferably 0.05% or less, the function of the electronic / electric device is improved.

(4) The crystal orientation of the rolled surface

The crystal orientation index A (hereinafter simply referred to as A value) given by the following equation is adjusted to 0.5 or more, more preferably 1.0 or more. Here, I _{( hkl )} and Io _(hkl) are the diffraction integral intensities of (hkl) planes obtained for the rolled surface and the copper _portion, respectively, by using the X-ray diffraction method.

A = 2X ₍₁₁₁₎ + X ₍₂₂₀₎ - X ₍₂₀₀₎

X _(hkl) = I _(hkl) / _{I0 (hkl)}

When the A value is adjusted to 0.5 or more, the creep elongation percentage becomes 0.1% or less, and the function of the electronic / electric apparatus is improved. The upper limit of the A value is not limited in view of the creep elongation, but the A value typically takes a value of 10.0 or less.

(5) Heat resistance, tensile strength, conductivity

In the course of processing into electronic components, the copper alloy foil is heat treated. For example, in the negative electrode collector of the secondary battery, the active material applied to the copper alloy foil is dried. In FCCL, heat is applied when a copper alloy foil is bonded to a resin film such as polyimide. If the copper alloy foil is softened by the heat treatment as described above, the function of the electronic / electric appliance is deteriorated.

Thus, in the present invention, the tensile strength of the copper alloy foil after heating at 300 캜 for 30 minutes is specified to be 300 MPa or more, preferably 350 MPa or more. 300 占 폚 and 30 minutes are harsh compared with the general heating conditions in the heat treatment for processing the copper alloy foil and it can be said that sufficient heat resistance is maintained if the tensile strength of 300 MPa or more is maintained after the heat treatment. The added element is selected so that the tensile strength after heating at 300 DEG C for 30 minutes is 300 MPa or more.

In order to maintain a tensile strength of 300 MPa or more after heating at 300 占 폚 for 30 minutes, it is preferable that the tensile strength is 350 MPa or more before heating, and more preferably 400 MPa or more.

The conductivity of a conventional rolled copper foil made of tough pitch copper is about 100% IACS, but if the conductivity is lowered by copper alloying the material, the function of the electronic and electric devices tends to be deteriorated. Therefore, the conductivity of the copper alloy foil is defined as 80% IACS or higher, preferably 83% IACS or higher. At this level, the function of the electric / electronic device is not deteriorated.

(6) Manufacturing method

The alloy element is added to the molten metal whose oxygen concentration is adjusted and cast into an ingot having a thickness of about 30 to 300 mm. This ingot is made into a plate having a thickness of about 3 to 30 mm by hot rolling, and then cold rolling and recrystallization annealing are repeated and finished to a predetermined product thickness for the final cold rolling.

The method of adjusting the A value to 0.5 or more is not limited to a specific method, but is possible by, for example, controlling the hot rolling condition. In the hot rolling of the present invention, the ingot heated to 800 to 1000 占 폚 is repeatedly passed between the pair of rolling rolls to finish to the target plate thickness. The machining degree per one pass affects the A value. Here, the processing degree R (%) per one pass means a reduction rate of the plate thickness when the rolling roll is passed once, where R = (T ₀ - T) / T ₀ × 100 (T ₀ : thickness before rolling roll, : Thickness after passing through the rolling roll).

For this R, it is preferable to set the maximum value Rmax in the entire path to 25% or less and the average value Rave of the entire path to 20% or less. When both these conditions are satisfied, the A value becomes 0.5 or more. More preferably, Rave is set to 19% or less.

In recrystallization annealing, some or all of the rolled structure is recrystallized. In the recrystallization annealing before the final cold rolling, the average grain diameter is adjusted to 50 μm or less. If the average grain diameter is excessively large, it is difficult to adjust the tensile strength of the product to 350 MPa or more.

The conditions of the recrystallization annealing before final cold rolling are determined based on the target crystal grain size after annealing. More specifically, annealing may be performed at a furnace temperature of 250 to 800 占 폚 by using a batch furnace or a continuous annealing furnace. In the batch furnace, the heating time may be appropriately adjusted within a range of 30 minutes to 30 hours at a furnace temperature of 250 to 600 ° C. In the continuous annealing furnace, the heating time may be appropriately adjusted within a range of 5 seconds to 10 minutes at a furnace temperature of 450 to 800 ° C.

In the final cold rolling, the material is repeatedly passed between the pair of rolling rolls to finish with the target plate thickness. The degree of processing of the final cold rolling is preferably 25 to 99%. Here, the processing degree r (%) is given by r = (t ₀ - t) / t ₀ × 100 (t ₀ : plate thickness before rolling, t: plate thickness after rolling). When r is too small, it is difficult to adjust the tensile strength to 350 MPa or more. If r is excessively large, the edge of the rolled material may be cracked.

(7) Examples of using copper alloy foil

(7-1) Lithium ion secondary battery

(Configuration of Battery)

The negative electrode plate and the secondary battery according to the present invention are characterized in that the copper alloy foil is used as a negative electrode current collector. The constitution other than the above is not limited, and commonly known positive electrode plates and secondary batteries can be used.

(Negative electrode)

The negative electrode is composed of a copper alloy foil as a negative electrode collector and a negative electrode active material formed on one or both surfaces of the negative electrode collector.

A paste obtained by kneading and dispersing a negative electrode active material and a binder in a solvent is applied to one side or both sides of a copper alloy foil to form a negative electrode plate and is heated at a temperature of 150 to 300 캜 for several hours to several hours while being pressurized, , And then formed into a negative electrode plate having a predetermined shape.

Examples of the negative electrode active material include carbonaceous substances, metals, metal compounds (metal oxides, metal sulfides, metal nitrides), and lithium alloys capable of intercalating and deintercalating lithium.

Examples of the carbonaceous material include graphite or carbonaceous materials such as graphite, coke, carbon fiber, spherical carbon, pyrolytic carbonaceous material and resin calcined material; A graphitic material or a carbonaceous material obtained by subjecting a thermosetting resin, isotropic pitch, mesophase pitch carbon, mesophase pitch carbon fiber, mesophase bead or the like to heat treatment at 500 to 3000 占 폚; And the like.

Examples of the metal include lithium, aluminum, magnesium, tin and silicon.

Examples of the metal oxide include tin oxide, silicon oxide, lithium titanium oxide, niobium oxide, and tungsten oxide. Examples of the metal sulfide include tin sulfide and titanium sulfide. Examples of the metal nitride include lithium cobalt nitride, lithium iron nitride, lithium manganese nitride, and the like.

Examples of lithium alloys include lithium aluminum alloys, lithium tin alloys, lithium lead alloys, and lithium silicon alloys.

The negative electrode active material-containing layer may contain a binder. As the binder, for example, organic solvent-based polyvinylidene fluoride (PVDF), water dispersion system styrene butadiene rubber (SBR), or the like can be used. As SBR, for example, carboxymethyl cellulose (CMC) may be used as a thickening agent. By using a mixture of SBR and CMC, the adhesion between the negative electrode active material and the current collector can be further enhanced.

The negative electrode active material-containing layer may contain a conductive agent. Examples of the conductive agent include graphite such as acetylene black and powdery expanded graphite, carbon fiber ground product, and graphitized carbon fiber ground product.

(Positive electrode)

The positive electrode is composed of a positive electrode current collector and a positive electrode active material-containing layer formed on one side or both sides of the positive electrode current collector.

Examples of the positive electrode collector include an aluminum plate and an aluminum mesh material.

Examples of the positive electrode active material include chalcogen compounds such as manganese dioxide, molybdenum disulfide, LiCoO ₂ , LiNiO ₂ and LiMn ₂ O ₄ . These chalcogen compounds may be used in a mixture of two or more kinds.

The positive electrode active material-containing layer may contain a binder. As the binder, a fluororesin, a polyolefin resin, a styrene resin, a thermoplastic elastomer resin such as an acrylic resin, or a rubber resin such as a fluororubber can be used. As an example thereof, polytetrafluoroethylene (PTFE) can be mentioned. As the thickening agent, for example, CMC may be used in combination with the binder.

The active material-containing layer may further contain graphite such as acetylene black, powdered expanded graphite, carbon fiber pulverized material, graphitized carbon fiber pulverized material, etc. as the conductive auxiliary material.

(Separator)

A separator or a solid or gel-like electrolyte layer can be disposed between the positive electrode and the negative electrode. As the separator, for example, a polyethylene porous film or a polypropylene porous film having a thickness of 20 to 30 mu m can be used.

(Non-aqueous electrolyte)

The non-aqueous electrolyte may be in the form of a liquid, a gel or a solid. It is preferable that the nonaqueous electrolyte contains a nonaqueous solvent and an electrolyte dissolved in the nonaqueous solvent.

Examples of the non-aqueous solvent include ethylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate,? -Butyrolactone, methyl propionate and the like. The non-aqueous solvent used may be one kind or two or more kinds.

Examples of the electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), and lithium hexafluoride (LiAsF ₆ ). The electrolyte may be used alone or in the form of a mixture.

(7-2) FCCL

(Configuration of FCCL)

The FCCL according to the present invention is characterized in that the copper alloy foil is used as a conductor, and the constitution other than the above is not limited, and a conventionally known copper alloy foil can be used.

(Bonding treatment of copper alloy foil)

The surface of the copper alloy foil after the final cold rolling is roughened for the purpose of improving adhesion with the resin layer due to the anchoring effect. As the method of harmonization, methods such as blasting, mechanical polishing, electrolytic polishing, chemical polishing and plating of electrodeposited lips are known, among which plating of electrodeposited lips (plating of plating) is widely used. The harmonious plating is to form fine irregularities by electrodepositing a large number of metal such as dendritic or small spherical copper on the copper foil surface.

(Formation of resin layer)

FCCL is produced by laminating a copper alloy foil on one side or both sides of a polyimide-based resin layer. There are three types of FCCL and two-layer FCCL depending on the stacking method.

In the three-layer FCCL, a copper foil and a polyimide resin film are laminated using an adhesive made of a thermosetting resin such as epoxy. In order to cure the adhesive, for example, heat treatment is performed at a temperature of 130 to 170 캜 for about 0.5 to 50 hours.

In the casting method which is one of the methods for producing the two-layer FCCL, a varnish containing polyamic acid, which is a precursor of polyimide resin, is coated on a copper foil and thermally cured to form a polyimide film on the copper foil. In this heat curing treatment, it is heated at a temperature of about 300 to 450 ° C. for about 5 to 40 minutes.

In the case of laminating copper alloy foils on both sides, there is a method in which a single-sided copper clad laminate is formed and then a copper foil layer is pressed by a hot press, a method in which a polyimide film is sandwiched between two copper foil layers, .

The polyimide-based resin layer is not particularly limited as long as it can use any known material. In the case of the two-layer FCCL, generally, a polyimide precursor resin (polyamic acid) obtained by reacting a known diamine and an acid anhydride in the presence of a solvent, And then heat-treating it. The polyimide-based resin layer may be composed of only a single layer, or may be formed of a plurality of layers. In the case of forming a plurality of polyimide resin layers, other polyimide resin may be sequentially coated on the polyimide resin layer made of different constituent components. When the polyimide resin layer is composed of three or more layers, a polyimide resin having the same constitution may be used twice or more.

Example

Examples of the present invention will be described below with reference to comparative examples. However, these examples are provided for better understanding of the present invention and its advantages, and are not intended to limit the invention.

After alloying elements were added to the furnace, they were cast into an ingot having a thickness of 200 mm. The ingot was heated at 950 占 폚 for 3 hours and hot rolled to form a plate having a thickness of 15 mm. After the oxide scale on the surface of the plate after hot rolling was grinded and removed, annealing and cold rolling were repeated, and the final product was finished to a predetermined product thickness by cold rolling.

In the hot rolling, the maximum value (Rmax) and the average value (Rave) of the processing degree per one pass were variously changed.

Final recrystallization annealing (annealing just before final cold rolling) was performed using a continuous annealing line. The furnace temperature (furnace retention time) of the material was adjusted so that the furnace temperature was 700 ° C and the grain size after annealing was 10 to 20 μm.

In order to change the degree of processing (r) in the final cold rolling, the thickness of the plate subjected to the final recrystallization annealing was adjusted in advance.

The copper alloy foil after the final cold rolling was subjected to the following investigation.

(ingredient)

The alloy element concentration of the foil after the final cold rolling was analyzed by ICP-mass spectrometry.

(Tensile strength, heat resistance)

IPC-TM-650, IPC (Institute for Interconnecting and Printing) Circuits standards for final cold-rolled finish foil; Tensile strength was determined according to Method 2.4.19. The specimen was 12.7 mm in width and 150 mm in length, and the specimen was taken in such a manner that the longitudinal direction thereof was parallel to the rolling direction. The tensile speed was set at 50 mm / min. The tensile strength of the sample after heating at 300 ° C for 30 minutes was also determined in the same manner.

(Conductivity)

With respect to the sample subjected to the final cold-rolled finish, the conductivity at 20 캜 was determined by a dividing method using a test piece for tensile test.

(Crystal orientation of the rolled surface)

The integrated X-ray diffraction intensity (I _(hkl) ) of the (hkl) plane in the thickness direction was measured with respect to the surface of the foil after the final cold rolling. The X-ray diffraction integrated intensity (I _{0 (hkl)} ) of the (hkl) plane was also measured for copper powder (copper (powder), 2N5,> 99.5%, 325 mesh manufactured by Kanto Kagaku Co., Ltd.). The RINT2500 manufactured by Rigaku Corporation was used as the X-ray diffraction apparatus, and measurement was made with Cu tube (bulb) at a tube voltage of 25 kV and a tube current of 20 mA. The measurement plane ((hkl)) has three surfaces of (111), (220) and (100), and the A value was calculated by the following equation.

A = 2X ₍₁₁₁₎ + X ₍₂₂₀₎ - X ₍₂₀₀₎

X _(hkl) = I _(hkl) / _{I0 (hkl)}

Further, when the copper alloy foil is thin and there is a fear that X-rays may penetrate through the sample, a plurality of samples are stacked and measured.

(Creep characteristics)

A test piece having a width of 15.5 mm and a length of 200 mm was taken from the foil after the final cold rolling so that the longitudinal direction of the test piece was parallel to the rolling direction. Next, two marks were drawn in the widthwise center of the test piece at intervals of L ₀ (= 100 mm) in the longitudinal direction. Thereafter, as shown in Fig. 1, one end of the test piece was supported, the test piece was hanged down, and the weight was attached to the other end. The mass of the weight was adjusted so that the tensile stress applied to the test specimen was 100 ㎫. In this state, it was allowed to stand at 30 DEG C for 100 hours. The weights were removed and the interval (L) was measured. The creep elongation (%) was calculated by the formula (L - L ₀ ) / L ₀ × 100.

(Bending life of FPC)

FPC samples for bending test were prepared in the following order.

(A) Coarse plating was performed on one side of the foil after final rolling. The copper plating was made of copper-cobalt-nickel plating, and copper was attached to 17 mg / dm ² , cobalt to 2000 μg / dm ² , and nickel to 500 μg / dm ² .

(B) A commercially available polyimide precursor varnish (trade name U-Varnish-A, manufactured by Ube Industries, Ltd.) was applied and dried on the copper plating surface of the copper alloy foil in the production line of the FCCL, To obtain a laminate having a polyimide precursor resin layer. This laminate was placed in an oven and subjected to heat treatment at 300 DEG C for 30 minutes to obtain a single-sided FCCL having a thickness of 25 mu m of polyimide resin.

(C) A test piece having a width of 8 mm and a length of 150 mm was taken from the FCCL so that its longitudinal direction was parallel to the rolling direction.

(D) A 0.2-mm wide line-and-space circuit was formed on the test piece, and the cover material was laminated on the circuit by pressing to obtain an FPC for bending test. CISV-1215 manufactured by Nikkan Kogyo Co., Ltd. was used as a cover material.

In the bending test, an FPC sample was subjected to flexural deformation repeatedly under the conditions of a curvature radius of 1.25 mm, a vibration stroke of 20 mm, and a vibration speed of 1,500 rpm using an IPC bending tester manufactured by Shin-Etsu Engineering Co., The number of times until the resistance value rose by 5% was determined.

When the copper alloy foil is thin, the flexure life is increased because the deformation generated on the copper foil surface at the time of bending is small. Therefore, the bending life span according to the thickness was evaluated at three levels as shown in Table 1 below.

(Cycle life of lithium ion secondary battery)

For a copper alloy foil having a thickness of 0.010 mm, a cylindrical lithium ion secondary battery shown in Fig. 2 was manufactured in the following order and the cycle life was measured.

(a) 50 parts by weight of scaly graphite powder as a negative electrode active material, 5 parts by weight of SBR as a binder, and 23 parts by weight of an aqueous solution of a thickener dissolved in 99 parts by weight of water with respect to 1 part by weight of CMC as a thickener, To obtain a paste for use. This negative electrode paste was coated on the surface of the rolled copper foil sample on both sides with a thickness of 200 mu m by the doctor blade method and dried by heating at 300 DEG C for 30 minutes. After adjusting the thickness to 160 탆 by pressurization, the negative electrode plate 6 was obtained by molding by shearing.

(b) 50 parts by weight of LiCoO ₂ powder as a positive electrode active material, 1.5 parts by weight of acetylene black as a conductive agent, 7 parts by weight of a PTFE 50% by weight aqueous dispersion, and 41.5 parts by weight of a 1% by weight aqueous solution of CMC as a thickener, To obtain a paste for use. The paste for positive electrode was coated on a current collector made of aluminum foil having a thickness of 30 mu m on both sides at a thickness of about 230 mu m by a doctor blade method and dried at 200 DEG C for 1 hour. The thickness was adjusted to 180 탆 by pressurization, and then molded by shearing to obtain a positive electrode plate 5.

(c) The positive electrode plate 5 and the negative electrode plate 6 were insulated with a separator 7 made of a microporous membrane made of polypropylene resin having a thickness of 20 占 퐉 interposed therebetween, (8).

(d) A negative electrode lead 9 connected to the negative electrode plate 6 was electrically connected via the case 8 and the lower insulating plate 10. Likewise, the positive electrode lead 3 connected to the positive electrode plate 5 was electrically connected to the internal terminal of the sealing plate 1 via the upper insulating plate 4. Thereafter, the nonaqueous electrolyte solution was injected, and the sealing plate 1 and the battery case 8 were caulked and sealed with an insulating gasket 2 interposed therebetween. The battery had a diameter of 17 mm and a height of 50 mm, a battery capacity of 780 mAh A cylindrical lithium ion secondary battery was fabricated.

(e) The electrolytic solution was prepared by injecting a predetermined amount of an electrolytic solution containing 1.0 mol of LiPF ₆ as an electrolyte in a mixed solvent of 30% by volume of ethylene carbonate, 50% by volume of methyl ethyl carbonate and 20% by volume of methyl propionate. This electrolyte solution was impregnated into the positive electrode active material layer and the negative electrode active material layer.

The charge and discharge cycle characteristics were evaluated using the produced battery. The discharge capacity at the third cycle was taken as the initial capacity, and the number of cycles was counted until the discharge capacity decreased to 80% with respect to the initial capacity, and this was taken as the cycle life. Charging condition: Constant current-constant voltage charging was performed at 4.2 V for 2 hours. After charging at a constant current of 550 mA (0.7 CmA) until the battery voltage reached 4.2 V, the current value was again reduced to 40 mA ㎃). Discharge condition: Discharge was performed to a discharge end voltage of 3.0 V at a constant current of 780 mA (1 CmA). Good (?) When the cycle life was 600 or more, and poor (x) when the cycle life was less than 600 was evaluated.

Table 2 shows the evaluation results. Table 3 shows Examples of Production Example 1, Production Example 4, Comparative Example 1 and Comparative Example 5 in Table 2 as the finish thickness of the material in each pass of hot rolling and the degree of processing per pass.

In the copper alloy foil of Inventive Examples 1 to 27, 0.01 to 0.50 mass% of a total of one or more of Ag, Cr, Fe, In, Ni, P, Si, Sn, Te, Ti, Zn and Zr is added, In rolling, Rmax was set to 25% or less and Rave was set to 20% or less, and the processing degree in the final cold rolling was set to 25 to 99%. As a result, the A value was 0.5 or more, and the creep elongation was 0.1% or less. Further, a conductivity of 80% IACS or more was obtained, and a tensile strength of 300 MPa or more was obtained after heating at 300 DEG C for 30 minutes.

The flexural characteristics of the inventive example having a creep elongation of 0.05% or less were evaluated as?, And the flexural characteristics of the inventive example having a creep elongation of 0.06 to 0.1% were evaluated as?.

In addition, the battery characteristics of the inventive example were evaluated as?.

In Comparative Examples 1 to 6, the value of A was less than 0.5, and the creep elongation percentage exceeded 0.1% because Rmax or Rave or both were out of the specification of the present invention. As a result, both of the flexural characteristics and the battery characteristics were evaluated.

In Comparative Example 7, the total of at least one of Ag, Cr, Fe, In, Ni, P, Si, Sn, Te, Ti, Zn and Zr was less than 0.01% by mass. 300 MPa. Thus, in Comparative Example 7, since the heat resistance was inferior, the FPC was softened during the production of the bending test FPC, and the flexural characteristic was evaluated as x even though the creep elongation was 0.1% or less.

1: Blank plate
2: Insulation gasket
3: Positive lead
4: upper insulating plate
5: Positive electrode plate
6: negative plate
7: Separator
8: Battery case
9: Negative lead
10: Lower insulating plate

Claims (13)

Wherein the total amount of the at least one element selected from the group consisting of Ag, Cr, Fe, In, Ni, P, Si, Sn, Te, Ti, Zn and Zr in a total amount of 0.01 to 0.50 mass% Or more and a tensile strength of 300 MPa or more after heating at 300 占 폚 for 30 minutes and an A value given by the following equation is 0.5 or more:
A = 2X ₍₁₁₁₎ + X ₍₂₂₀₎ - X _{(200)
X (hkl) = I (hkl} ) / I 0 (hkl)
However, I _(hkl) and I _{0 (hkl)} is an integrated intensity of the diffraction obtained (hkl) plane with respect to the rolling surface and the copper powder by using the X-ray diffraction, respectively. Wherein the total amount of the at least one element selected from the group consisting of Ag, Cr, Fe, In, Ni, P, Si, Sn, Te, Ti, Zn and Zr in a total amount of 0.01 to 0.50 mass% Or more and having a tensile strength of 300 MPa or more after heating at 300 占 폚 for 30 minutes and an elongation of 0.1% or less when maintained at 100 占 폚 under a tensile stress of 30 MPa at 30 占 폚. 3. The method according to claim 1 or 2,
Zr in an amount of 0.01 to 0.20 mass%, and the balance of Cu and impurities. 3. The method according to claim 1 or 2,
Sn in an amount of 0.01 to 0.20 mass%, and the balance of Cu and impurities. 3. The method according to claim 1 or 2,
And 0.05 to 0.50 mass% of Ag, and the balance of Cu and impurities. 3. The method according to claim 1 or 2,
0.05 to 0.50% by mass of Fe and 0.005 to 0.10% by mass of P, and the balance of Cu and impurities. 3. The method according to claim 1 or 2,
Wherein the copper alloy foil has a thickness of 0.003 to 0.05 mm. 3. The method according to claim 1 or 2,
A copper alloy foil used for an anode current collector of a secondary battery. A secondary battery using a negative electrode current collector comprising the copper alloy foil according to claim 8. 3. The method according to claim 1 or 2,
A copper alloy foil used for a flexible copper clad laminate. A flexible copper clad laminate comprising the copper alloy foil according to claim 10. 3. The method according to claim 1 or 2,
A copper alloy foil used for an electromagnetic shielding body. An electromagnetic wave shielding body comprising the copper alloy foil according to claim 12.

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