TWI502085B - Copper alloy foil - Google Patents

Description

Copper alloy foil

The present invention relates to an electromagnetic wave shield which is suitable as a negative electrode current collector material for a secondary battery typified by a lithium ion secondary battery (LIB), a conductive material of a soft copper clad laminate (FCCL), and a wire coating material. Copper alloy foils such as materials and electronic parts using the same.

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

For example, JP-A-2009-097075 (Patent Document 1) discloses a copper foil for FCCL, in which two or more of Sn, Mg, In, and Ag are added to Cu to improve heat resistance and flexibility. Alloy foil. In addition, in order to improve the charge and discharge cycle life of the secondary battery, the copper foil for the negative electrode current collector is used for adding Ag, Cr, Fe to Cu, and is disclosed in JP-A-2011-216463 (Patent Document 2). A copper alloy foil having one or more of In, Ni, P, Si, Sn, Te, Ti, Zn, and Zr and having an anisotropy of Young's modulus.

[Previous Technical Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2009-097075

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2011-216463

With the miniaturization and high functionality of electronic and electrical equipment, the requirements for the characteristics of copper foil are increasing. For example, the charge and discharge cycle life of the negative electrode current collector of the secondary battery, the bending life of the FCCL, and the durability of the electromagnetic wave shield can be mentioned. An object of the present invention is to provide a copper alloy foil that can cope with such requirements.

The present inventors have found that if the stress below the elastic limit of the copper alloy foil is maintained for a long period of time, a slight elongation occurs even at room temperature. Further, the inventors have found that the use of the copper alloy foil having a small creep elongation (hereinafter referred to as creep) generated at room temperature improves the functionality of electronic and electrical equipment.

For example, when a carbonaceous material or the like is applied as an active material to the copper alloy foil, and LIB is produced as a negative electrode current collector, the charge and discharge cycle life of the LIB is improved. During charging of the LIB, lithium ions move from the positive electrode to the negative electrode, and during discharge, lithium ions move from the negative electrode to the positive electrode. As the lithium ion moves, the negative electrode active material expands and contracts, so that the copper foil is subjected to mechanical stress due to charge and discharge. As a result, the copper foil was permanently deformed and the active material was peeled off, and the battery characteristics were deteriorated. In the case of a copper alloy foil having a small creep, the permanent deformation of the copper alloy foil under the creep stress is reduced, and the deterioration of the battery characteristics is improved.

Moreover, when FCCL is produced using a copper alloy foil having a small creep, the flexural life of the flexible printed circuit board (FPC) produced by using the FCCL is improved. In the case of a copper alloy foil having a small creep, the permanent deformation of the copper alloy foil when the FPC is subjected to bending is reduced, whereby crack generation and growth of the copper alloy foil are suppressed.

Similarly, in the wire coating material for electromagnetic wave shielding, if a copper foil having a small creep is used, the damage of the copper alloy foil when the electric wire is repeatedly bent may be reduced.

Although the creep elongation of the copper alloy foil is extremely small, it is presumed that the influence as described above becomes apparent in an environment in which the overcoat stress is long-term.

Further, the inventors conducted intensive studies and found that the orientation of the crystal grains in the rolling surface of the copper alloy foil affects the creep. Specifically, in order to reduce creep, it is effective to increase the (111) plane and the (220) plane on the rolling surface, and conversely, it is more harmful to increase the (200) plane. Moreover, after experimental research, the crystal orientation index of the index of creep is invented, and the index is controlled, whereby the creep can be reduced.

The present invention based on the above findings provides a copper alloy foil containing 0.01 to 0.50% by mass of Ag, Cr, Fe, In, Ni, P, Si, Sn, Te, Ti, Zn and Zr in a single aspect. One or more of them and the remainder consisting of Cu and impurities, having a conductivity of 80% IACS or more, and maintaining a tensile strength of 300 MPa or more after heating at 300 ° C for 30 minutes, the A value shown in the following formula is 0.5 or more, A =2X ₍₁₁₁₎ +X ₍₂₂₀₎ -X ₍₂₀₀₎

X _(hkl) =I _(hkl) /I _0(hkl)

Among them, I _(hkl) and I _{0 (hkl)} are diffraction integral intensities of the (hkl) plane obtained by the X-ray diffraction method on the rolled surface and the copper powder, respectively.

Moreover, in another aspect of the present invention, a copper alloy foil comprising 0.01 to 0.50% by mass of Ag, Cr, Fe, In, Ni, P, Si, Sn, Te, Ti, Zn and Zr is provided. One or more and the remainder consisting of Cu and impurities, having a conductivity of 80% IACS or more, maintaining a tensile strength of 300 MPa or more after heating at 300 ° C for 30 minutes, and applying a tensile stress of 100 MPa at 30 ° C for 100 hours. The elongation is 0.1% or less.

The copper alloy foil preferably contains 0.01 to 0.20% by mass of Zr and the remainder is composed of Cu and impurities.

The copper alloy foil preferably contains 0.01 to 0.20% by mass of Sn and the remainder is composed of Cu and impurities.

The copper alloy foil preferably contains 0.05 to 0.50% by mass of Ag and the remainder is composed of Cu and impurities.

The copper alloy foil preferably contains 0.05 to 0.50% by mass of Fe, 0.005 to 0.10% by mass of P, and the remainder is composed of Cu and impurities.

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

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

In this regard, the present invention provides, in another aspect, a secondary battery using a negative electrode current collector composed of the above copper alloy foil.

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

In this regard, the present invention provides, in another aspect, a soft copper clad laminate which is composed of the above copper alloy foil.

Each of the above copper alloy foils can be used for an electromagnetic wave shield.

In this regard, the present invention provides an electromagnetic wave mask in another aspect, which is The copper alloy foil is constructed.

1‧‧‧ sealing plate

2‧‧‧Insulation gasket

3‧‧‧positive lead

4‧‧‧Upper insulation board

5‧‧‧ positive plate

6‧‧‧Negative plate

7‧‧‧Parts

8‧‧‧ battery housing

9‧‧‧Negative lead

10‧‧‧Lower insulation board

Fig. 1 is a view for explaining the principle of measurement of creep characteristics.

Fig. 2 is a schematic view showing the structure of a general secondary battery.

(1) Composition of copper foil

In order to improve the strength and heat resistance of the copper foil, the copper alloy foil of the present invention contains 0.01 to 0.50% by mass of Ag, Cr, Fe, In, Ni, P, Si, Sn, Te, Ti, Zn and the total copper. More than one of Zr. When the total amount of the above elements exceeds 0.50% by mass, the electrical conductivity is lowered and it is not suitable as a conductive material. When the total amount of the added elements is less than 0.01% by mass, the effect of containing the elements cannot be expressed and the strength or heat resistance is insufficient.

As the base Cu material, the oxygen-free copper specified in JIS-C1020 or the refined copper specified in JIS-C1100 is suitable. The oxygen concentration of the oxygen-free copper melt is usually 0.001% by mass or less, and the oxygen concentration of the refined copper melt is usually 0.01 to 0.05% by mass.

When an element of any one or more of Cr, Fe, In, Ni, P, Si, Sn, Te, Ti, Zn, and Zr which is easily oxidized than Cu is used, it is not possible to obtain an oxide in order to avoid formation of an oxide of the element. The heat resistance improving effect is usually added to the oxygen-free copper melt.

Since Ag is less susceptible to oxidation than Cu, it can be added together to the molten copper melt and the oxygen-free copper melt.

Addition of Ag, Cr, Fe, In, Ni, P, Si, Sn, Te, Ti, Zn and Zr The amount is suitably adjusted within a range of 0.01 to 0.50% by mass in total to satisfy the tensile strength, heat resistance, and electrical conductivity of the following targets.

By adding Ag and Te, the strength and heat resistance can be improved with little reduction in electrical conductivity.

Sn and In show a relatively high effect on the improvement of strength and heat resistance, and the operation of the ingot is relatively easy to melt.

Zr, Ti, and Cr are precipitated in Cu to significantly improve strength and heat resistance, but since the activity is very strong, oxides or carbides are easily formed in the molten copper. If an oxide or a carbide is formed, the material is broken or pinholes are generated during the rolling of the foil, so care must be taken when the ingot is melted.

Fe and Ni are precipitated at the same time as P or Si to precipitate a compound such as Fe-P, Ni-P, Fe-Si, or Ni-Si, and higher strength and heat resistance can be obtained than when added alone.

The effect of improving the strength or heat resistance of Zn is not too large, but it also has the effect of improving the surface properties such as plating property or migration resistance.

The effect of the present invention can be particularly exhibited in the copper alloy foil of the following composition.

(a) A copper alloy foil comprising 0.01 to 0.20% by mass of Zr and the balance being composed of Cu and impurities.

(b) A copper alloy foil comprising 0.01 to 0.20% by mass of Sn and the balance being composed of Cu and impurities.

(c) A copper alloy foil comprising 0.05 to 0.50% by mass of Ag and the remainder being composed of Cu and impurities.

(d) A copper alloy foil comprising 0.05 to 0.50% by mass of Fe, 0.005 to 0.10% by mass of P, and the balance being composed of Cu and impurities.

(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, the operation of the copper alloy foil becomes difficult. When the thickness exceeds 0.05 mm, miniaturization of electronic components becomes difficult. A more preferable thickness is 0.005 to 0.02 mm.

(3) Creep characteristics

As the creep property, the elongation at which a tensile stress of 100 MPa was applied at 30 ° C and held for 100 hours was evaluated. When the elongation is 0.1% or less, more preferably 0.05% or less, the functions of electronic and electrical equipment are improved.

(4) Crystal orientation of the calendering surface

The crystal orientation index A (hereinafter, abbreviated as A value) shown in the following formula is adjusted to 0.5 or more, and more preferably adjusted to 1.0 or more. Here, I _(hkl) and I _{0 (hkl)} are diffraction integral intensities of the (hkl) plane obtained by the X-ray diffraction method for the rolled surface and the copper powder, respectively.

A=2X ₍₁₁₁₎ +X ₍₂₂₀₎ -X ₍₂₀₀₎

X _(hkl) =I _(hkl) /I _0(hkl)

When the A value is adjusted to 0.5 or more, the creep elongation is 0.1% or less, and the functions of electronic and electrical equipment are improved. Regarding the upper limit of the A value, although there is no limitation on the above creep elongation, the A value is typically a value of 10.0 or less.

(5) heat resistance, tensile strength, electrical conductivity

In the process of processing into electronic parts, the copper alloy foil is subjected to heat treatment. For example, in the case of the negative electrode current collector of the secondary battery, drying of the active material applied to the copper alloy foil is performed. also, In the case of 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 during such heat treatment, the functions of the electronic and electrical equipment are lowered.

Therefore, in the present invention, the tensile strength of the copper alloy foil after heating at 300 ° C for 30 minutes is set to 300 MPa or more, preferably 350 MPa or more. The normal heating conditions in the heat treatment at the time of processing the copper alloy foil at 300 ° C for 30 minutes are strict, and if the tensile strength of 300 MPa or more is maintained after the heat treatment, sufficient heat resistance can be said. The above-mentioned additive element is selected so that the tensile strength after heating at 300 ° C for 30 minutes becomes 300 MPa or more.

In order to maintain the tensile strength of 300 MPa or more after heating at 300 ° C for 30 minutes, it is preferred to have a tensile strength of 350 MPa or more in a state before heating, and further preferably a tensile strength of 400 MPa or more.

The conductivity of the previously rolled copper foil using fine copper as a material is about 100% IACS. However, if the material is copper alloyed to lower the electrical conductivity, the function of electronic and electrical equipment tends to be lowered. Therefore, the conductivity of the copper alloy foil is set to 80% IACS or more, and preferably 83% IACS or more. If it is at this level, the functions of electronic and electrical equipment will not be reduced.

(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. The ingot is formed into a plate having a thickness of about 3 to 30 mm by hot rolling, and then subjected to cold rolling and recrystallization annealing, and finally processed into a specific product thickness by cold rolling.

The method of adjusting the A value to 0.5 or more is not limited to a specific method, and can be achieved, for example, by controlling hot rolling conditions. In the hot rolling of the present invention, an ingot heated to 800 to 1000 ° C is repeatedly passed between a pair of rolls, and finally processed into a target thickness. The degree of processing per stroke affects the value of A. Here, the degree of processing R (%) per stroke refers to the rate of decrease in thickness when passing through a single roll, and is expressed as R = (T _{0 -} T) / T ₀ × 100 (T ₀ : before passing the roll Thickness, T: thickness after passing the roll).

Regarding this R, it is preferable to set the maximum value (Rmax) of all the strokes to 25% or less, and to set the average value (Rave) of all the strokes to 20% or less. By satisfying these two conditions, the A value becomes 0.5 or more. More preferably, Rave is set to 19% or less.

At the time of recrystallization annealing, part or all of the rolled structure is recrystallized. At the time of recrystallization annealing before the final cold rolling, the average crystal grain size is adjusted to 50 μm or less. When the average crystal grain size is too large, it is difficult to adjust the tensile strength of the product to 350 MPa or more.

The conditions of the recrystallization annealing before the final cold rolling are determined based on the crystal grain size after the target annealing. Specifically, it is sufficient to perform annealing by using a batch furnace or a continuous annealing furnace and setting the furnace temperature to 250 to 800 °C. In the case of a batch furnace, the heating time may be suitably adjusted within a range of 30 minutes to 30 hours at an oven temperature of 250 to 600 °C. In the case of a continuous annealing furnace, the heating time may be suitably adjusted within a range of 5 seconds to 10 minutes at an oven temperature of 450 to 800 °C.

In the final cold rolling, the material is repeatedly passed between a pair of rolls, and finally processed to the target thickness. The final cold rolling degree is preferably set to 25 to 99%. Here, the degree of work r (%) is expressed as r = (t _{0 -} t) / t ₀ × 100 (t ₀ : plate thickness before rolling, t: plate thickness after rolling). If r is too small, it is difficult to adjust the tensile strength to 350 MPa or more. If r is too large, there is a case where the edge of the rolled material is broken.

(7) Use cases of copper alloy foil

(7-1) Lithium ion secondary battery

(Battery composition)

The negative electrode plate and the secondary battery of the present invention are characterized in that the copper alloy foil is used as the negative electrode current collector, and the other configuration is not limited, and those generally used can be used.

(negative electrode)

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

A paste obtained by mixing 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 if necessary, pressurized at 150 to 300 ° C. After heating at a temperature for several hours to several tens of hours and drying it, it is molded into a negative electrode plate of a specific shape.

Examples of the negative electrode active material include a carbonaceous material capable of absorbing and releasing lithium, a metal, a metal compound (metal oxide, metal sulfide, metal nitride), and a lithium alloy.

Examples of the carbonaceous material include graphite materials such as graphite, coke, carbon fibers, spherical carbon, pyrolytic gas phase carbonaceous materials, and resin fired materials, or carbonaceous materials; and thermosetting resins and isotropic pitches. A graphite material or a carbonaceous material obtained by heat-treating at 500 to 3000 ° C, such as mesophase pitch-based carbon, mesophase pitch-based carbon fiber, and mesophase small sphere.

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

Examples of the metal oxide include tin oxide, cerium oxide, lithium titanium oxide, cerium oxide, and tungsten oxide. Examples of the metal sulfides include tin sulfides and titanium sulfides. Examples of the metal nitride include lithium cobalt nitride, lithium iron nitride, and lithium manganese nitride.

Examples of the lithium alloy include a lithium aluminum alloy, a lithium tin alloy, a lithium lead alloy, and a lithium niobium alloy.

The binder may be contained in the negative electrode active material containing layer. As the binder, for example, an organic solvent-based polyvinylidene fluoride (PVDF) or a water-dispersible styrene butadiene rubber (SBR) can be used. For example, carboxymethyl cellulose (CMC) can be used in combination as an adhesion promoter in SBR. By using a mixture of SBR and CMC, the adhesion between the negative electrode active material and the current collector can be further improved.

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

(positive electrode)

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

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

Examples of the positive electrode active material include chalcogen compound compounds such as manganese dioxide, molybdenum disulfide, LiCoO ₂ , LiNiO ₂ , and LiMn ₂ O ₄ . These chalcogen compound compounds may also 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 thermoplastic elastomer resin such as a fluorine resin, a polyolefin resin, a styrene resin or an acrylic resin, or a rubber resin such as a fluororubber can be used. An example of this is polytetrafluoroethylene (PTFE). For example, CMC can be used as a tackifier in the adhesive.

The active material-containing layer may further contain graphite, such as acetylene black or powdery expanded graphite, a carbon fiber pulverized product, a graphitized carbon fiber pulverized product, or the like as a conductive auxiliary material.

(separator)

A separator or a solid or gel electrolyte layer may be disposed between the positive electrode and the negative electrode. As the separator, for example, a polyethylene porous film having a thickness of 20 to 30 μm, polypropylene can be used. Porous membranes, etc.

(non-aqueous electrolyte)

The nonaqueous electrolyte can be used in the form of a liquid, a gel or a solid. Further, the nonaqueous electrolyte is preferably an electrolyte containing a nonaqueous solvent and dissolved in the nonaqueous solvent.

Examples of the nonaqueous solvent include ethyl carbonate, methyl dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, γ-butyrolactone, and methyl propionate. The type of the nonaqueous solvent to be used may be one type or two or more types.

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

(7-2) FCCL

(Composition of FCCL)

The FCCL of the present invention is characterized in that the copper alloy foil is used as the conductor, and the other configuration is not limited, and those generally used can be used.

(roughening treatment of copper alloy foil)

In order to improve the adhesion to the resin layer obtained by the anchoring effect, the surface of the copper alloy foil after the final cold rolling is roughened. As a method of roughening treatment, methods such as blast processing, mechanical polishing, electrolytic polishing, chemical polishing, and plating of electroplated particles are known, and in particular, plating of electroplated particles (roughing plating) is used. . The roughening plating is performed by plating a large amount of metal such as dendritic or small spherical copper on the surface of the copper foil to form fine irregularities.

(formation of resin layer)

The FCCL is produced by a single-sided or two-layer copper alloy foil of a polyimide-based resin layer. root According to the layering method, there are three types of FCCL, two layers of FCCL and the like.

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

In a casting method which is one of the manufacturing methods of the two-layer FCCL, a varnish containing a poly-proline which is a precursor of a polyimide resin is applied onto a copper foil and heat-hardened on the copper foil. A polyimide film is formed. In the heat hardening treatment, it is heated at a temperature of about 300 to 450 ° C for about 5 to 40 minutes.

In the case of a two-layer copper alloy foil, there is a method of forming a single-sided copper-clad laminate and then laminating the copper foil by hot pressing, sandwiching the polyimide film between the two copper foil layers, and pressing it with hot pressing. The method of connection, etc.

The polyimine-based resin layer may be any known material, and is not particularly limited. In the case of two-layer FCCL, it is usually obtained by reacting a known diamine with an acid anhydride in the presence of a solvent. The quinone imine precursor resin (polyglycine) is formed by heat treatment. The polyimine-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 layers of a polyimide layer, it may be formed by sequentially coating another polyimide resin on a polyimide resin layer composed of different constituent components. When the polyimine resin layer is composed of three or more layers, the same composition of the polyimide resin may be used twice or more.

[Examples]

The embodiments of the present invention are shown in the following together with the comparative examples, but these are intended to provide a better understanding of the present invention and its advantages, and are not intended to limit the invention.

After adding an alloying element to the molten copper, it was cast into an ingot having a thickness of 200 mm. The ingot was heated at 950 ° C for 3 hours and hot rolled into a plate having a thickness of 15 mm. After the scale of the surface of the hot-rolled sheet is ground and removed, it is repeatedly subjected to annealing and cold rolling, and finally cold-rolled to be finally processed into a specific product thickness.

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

The final recrystallization anneal (i.e., annealing prior to final cold rolling) is carried out using a continuous annealing line. The furnace temperature was set to 700 ° C, and the material passing speed (the holding time in the furnace) was adjusted so that the crystal 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 final recrystallization annealing is adjusted in advance.

The following investigation was conducted on the copper alloy foil after the final cold rolling.

(ingredient)

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

(tensile strength, heat resistance)

The tensile strength was determined in accordance with the IPC (Institute for Interconnecting and Packaging Electronics Circuits) specification, IPC-TM-650; Method 2.4.19 for the foil which was finally cold rolled. The test piece was set to have a width of 12.7 mm and a length of 150 mm, and was taken so that the longitudinal direction of the test piece became parallel to the rolling direction. The stretching speed was set to 50 mm/min. Further, the tensile strength was also determined in the same manner for the sample heated at 300 ° C for 30 minutes.

(Conductivity)

For the sample subjected to the final cold rolling, a test piece for tensile test was used, and a conductivity of 20 ° C was obtained by a four-terminal method.

(crystal orientation of the rolling surface)

The X-ray diffraction integral intensity (I _(hkl) ) in the thickness direction (hkl) plane was measured for the surface of the foil after the final cold rolling. Further, for the copper powder (manufactured by Kanto Chemical Co., Ltd., copper (powder), 2N5, >99.5%, 325 mesh), the X-ray diffraction integral intensity (I _{0 (hkl)} ) of the (hkl) plane was also measured. The X-ray diffraction apparatus was measured using a RINT 2500 manufactured by Rigaku Co., Ltd., using a Cu bulb, at a tube voltage of 25 kV and a tube current of 20 mA. The measurement surface ((hkl)) was set to three sides of (111), (220), and (100), and the A value was calculated from the following formula.

A=2X ₍₁₁₁₎ +X ₍₂₂₀₎ -X ₍₂₀₀₎

X _(hkl) =I _(hkl) /I _0(hkl)

Further, when the copper alloy foil is thin and X-rays are transmitted through the sample, a plurality of samples are stacked and measured.

(creep property)

The foil after the final cold rolling was a test piece having a short strip shape having a width of 15.5 mm and a length of 200 mm so that the length direction of the test piece became parallel to the rolling direction. Then, at intervals of L ₀ (= 100 mm) in the longitudinal direction, two indentations were imprinted in the center in the width direction of the test piece. Thereafter, as shown in Fig. 1, one end of the test piece is supported and the test piece is suspended, and the other side is mounted with a vertical. The quality of the plumb was adjusted so that the tensile stress of the test piece became 100 MPa. In this state, it was allowed to stand at 30 ° C for 100 hours. The verticality was removed, and the dimple interval (L) was measured, and the creep elongation (%) was calculated from the equation of (LL ₀ ) / L ₀ × 100.

(FPC bending life)

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

(A) A rough plating is applied to one side of the finally rolled foil. The roughening plating system was copper-cobalt-nickel plating, copper was adhered to 17 mg/dm ² , cobalt was adhered to 2000 μg/dm ² , and nickel was adhered to 500 μg/dm ² .

(B) In the FCCL production line, a commercially available polyimine precursor varnish (manufactured by Ube Industries, Ltd., trade name U-VARNISH) is applied to the surface of the copper alloy foil which has been subjected to roughening plating. -A) and drying to obtain a laminate in which a polyimide film precursor layer is formed on the copper foil layer. The laminate was placed in an oven and heat-treated at 300 ° C for 30 minutes to obtain a single-sided FCCL having a polyimide resin thickness of 25 μm.

(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 became parallel to the rolling direction.

(D) A 0.2 mm wide line and gap circuit was formed on the test piece, and a cover material was laminated on the circuit to obtain an FPC for bending test. The cover material was CISV-1215 manufactured by NIKKAN INDUSTRIES.

In the bending test, the bending deformation was repeated on the FPC specimen under the conditions of a curvature radius of 1.25 mm, a vibration stroke of 20 mm, and a vibration speed of 1500 times/min using an IPC bending tester manufactured by Shin-Etsu Engineering Co., Ltd. The number of times until the resistance value of the sample rises by 5%.

When the copper alloy foil is thinned, the deformation occurring on the surface of the copper foil at the time of bending is reduced, so that the bending life is increased. Therefore, according to the foil thickness, the bending life was evaluated at a level of ◎○× as shown in Table 1.

(Cycle life of lithium ion secondary battery)

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

(a) 50 parts by weight of flaky graphite powder as a negative electrode active material, 5 parts by weight of SBR as a binder, and a tackifier obtained by dissolving 1 part by weight of CMC in 99 parts by weight of water as a tackifier 23 parts by weight of the aqueous solution was kneaded and dispersed to obtain a paste for a negative electrode. This negative electrode paste was applied to both surfaces of the surface of the rolled copper foil sample by a doctor blade method at a thickness of 200 μm, and dried by heating at 300 ° C for 30 minutes. After the pressure was adjusted to 160 μm, the negative electrode plate 6 was obtained by a shearing process.

(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 50% by weight aqueous dispersion of PTFE as a binder, and 1% by weight of CMC as a tackifier. 41.5 parts by weight of the aqueous solution was kneaded and dispersed to obtain a paste for a positive electrode. This positive electrode paste was applied to both surfaces of a current collector made of an aluminum foil having a thickness of 30 μm by a doctor blade method at a thickness of about 230 μm, and heated at 200 ° C for 1 hour to be dried. After the pressure was adjusted to 180 μm in thickness, the positive electrode plate 5 was obtained by molding by shearing.

(c) The positive electrode plate 5 and the negative electrode plate 6 are made of a polypropylene resin having a thickness of 20 μm. The electrode group which is wound in a spiral shape while being insulated by the separator 7 formed of the microporous film is housed in the battery case 8.

(d) The negative electrode lead 9 connected from the negative electrode plate 6 is electrically connected to the casing 8 via the lower insulating plate 10. Similarly, the positive electrode lead 3 connected from the positive electrode plate 5 is electrically connected to the internal terminal of the sealing plate 1 via the upper insulating plate 4. Then, the non-aqueous electrolyte solution was injected, and the sealing plate 1 and the battery case 8 were crimped and sealed via the insulating spacer 2, and a cylindrical lithium ion secondary battery having a battery capacity of 780 mAh was produced in a size of 17 mm in diameter and 50 mm in height. .

(e) The electrolyte solution is prepared by dissolving 1.0 mol of LiPF ₆ as an electrolyte in a mixed solvent of a specific amount of 30% by volume of ethyl carbonate, 50% by volume of methyl ethyl carbonate and 20% by volume of methyl propionate. The electrolyte. This electrolyte solution is 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 fabricated battery. The charge and discharge were performed in an environment of 20 ° C, and the discharge capacity at the third cycle was set as the initial capacitance, and the number of cycles was counted until the discharge capacity was reduced to 80% with respect to the initial capacitance, and this was set as the cycle life. Under the charging condition: 4.2V for 2 hours of constant current-fixed voltage charging, constant current charging of 550mA (0.7CmA) is performed until the battery voltage reaches 4.2V, and then the current value is attenuated and charged until it becomes 40mA (0.05CmA). . The discharge was performed under a constant current of 780 mA (1 CmA) until a discharge termination voltage of 3.0 V. When the cycle life was 600 or more, it was evaluated as good (○), and when it was less than 600 times, it was evaluated as poor (×).

The evaluation results are shown in Table 2. In Table 3, Invention Example 1, Invention Example 4, Comparative Example 1, and Comparative Example 5 of Table 2 are shown as the finished thickness of the material in each stroke of the hot rolling and the degree of processing per one stroke.

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

The bending property of the invention example having a creep elongation of 0.05% or less was evaluated as ◎, and the bending property of the inventive example having a creep elongation of 0.06 to 0.1% was evaluated as ○.

Moreover, the battery characteristics of the invention examples were evaluated as ○.

In Comparative Examples 1 to 6, Rmax or Rave, or both thereof deviated from the present invention. It is stipulated that the value of A is less than 0.5 and the creep elongation is more than 0.1%. As a result, both the bending property and the battery characteristics were evaluated as ×.

In Comparative Example 7, the total of one or more of Ag, Cr, Fe, In, Ni, P, Si, Sn, Te, Ti, Zn, and Zr was less than 0.01% by mass, so that it was heated at 300 ° C for 30 minutes. The tensile strength is less than 300 MPa. As described above, in Comparative Example 7, the heat resistance was inferior, so that the softening occurred during the production of the FPC for the bending test, and although the creep elongation was 0.1% or less, the bending property was also evaluated as ×.

Claims (13)

A copper alloy foil containing a total of 0.01 to 0.50% by mass of one or more of Ag, Cr, Fe, In, Ni, P, Si, Sn, Te, Ti, Zn, and Zr, and the remainder consisting of Cu and impurities. It has a conductivity of 80% IACS or more, and maintains a tensile strength of 300 MPa or more after heating at 300 ° C for 30 minutes. The A value shown in the following formula is 0.5 or more, and A = 2X ₍₁₁₁₎ + X ₍₂₂₀₎ - X _{( 200)} X _(hkl) = I _(hkl) / I _{0 (hkl)} where I _(hkl) and I _{0 (hkl)} are obtained by the X-ray diffraction method for the rolled surface and the copper powder (hkl) The diffraction integral intensity of the surface. A copper alloy foil containing a total of 0.01 to 0.50% by mass of one or more of Ag, Cr, Fe, In, Ni, P, Si, Sn, Te, Ti, Zn, and Zr, and the remainder consisting of Cu and impurities. It has a conductivity of 80% IACS or more, and after maintaining at 300 ° C for 30 minutes, the tensile strength of 300 MPa or more is maintained, and a tensile stress of 100 MPa is applied at 30 ° C and the elongation at 100 hours is maintained at 0.1% or less. A copper alloy foil according to claim 1 or 2, which contains 0.01 to 0.20% by mass of Zr and the remainder consists of Cu and impurities. A copper alloy foil according to claim 1 or 2, which contains 0.01 to 0.20% by mass of Sn and the remainder is composed of Cu and impurities. A copper alloy foil according to claim 1 or 2, which contains 0.05 to 0.50% by mass of Ag and the remainder is composed of Cu and impurities. The copper alloy foil according to claim 1 or 2, which contains 0.05 to 0.50% by mass of Fe, 0.005 to 0.10% by mass of P, and the remainder consists of Cu and impurities. The copper alloy foil of claim 1 or 2 has a thickness of 0.003 to 0.05 mm. A copper alloy foil according to claim 1 or 2, which is used for a negative electrode current collector of a secondary battery. A copper alloy foil as claimed in claim 1 or 2, which is used for a soft copper clad laminate. A copper alloy foil as claimed in claim 1 or 2, which is used for an electromagnetic wave shield. A secondary battery using a negative electrode current collector composed of a copper alloy foil of the eighth application of the patent application. A soft copper-clad laminate comprising a copper alloy foil of claim 9 of the patent application. An electromagnetic wave mask comprising a copper alloy foil of the tenth patent application.