CN102453812A - Rolled copper foil and method for manufacturing rolled copper foil - Google Patents

Abstract

The present invention provides a rolled copper foil having high electrical conductivity and a high bending life even if it is a soft copper material, and a method for producing the rolled copper foil. The rolled copper foil of the present invention contains oxygen in an amount exceeding 2 mass ppm in pure copper containing unavoidable impurities, and a metal selected from the group consisting of Mg, Zr, Nb, Ca, V, Ni, Mn, Ti, and Cr. The added element in the group.

Description

Rolled copper foil and method for producing rolled copper foil

technical field

The present invention relates to a rolled copper foil and a method for producing the rolled copper foil.

Background technique

In recent science and technology, electricity is used for all parts such as electric power as a power source and electric signals, and wires such as cables and leads are used to transmit them. Therefore, metals with high electrical conductivity, such as copper and silver, are used as raw materials for the wires, and copper wires are mostly used in consideration of cost.

All copper is roughly classified according to its molecular arrangement, etc., and can be divided into hard copper and soft copper. Therefore, copper having desired properties is used according to the purpose of use.

As far as lead wires for electronic components are concerned, hard copper wires are mostly used. For example, cables used for electronic equipment such as medical equipment, industrial robots, and notebook personal computers are subject to severe bending, torsion, and stretching under repeated loads It is used in an environment of external force, so hard and straight hard copper wires are not appropriate, and soft copper wires can be used.

Copper wires used in such applications are required to have the opposite characteristics of good electrical conductivity (high electrical conductivity) and good bending properties, but so far, development of copper materials that maintain high electrical conductivity and bending resistance has been progressing .

For example, as a conductor for a bend-resistant cable having good tensile strength, elongation, and electrical conductivity, a conductor for a bend-resistant cable in which a copper alloy is formed into a wire rod is known. Indium with a purity of 99.99 wt % or higher is contained in a concentration range of 0.05 to 0.70 mass %, and P with a purity of 99.9 wt % or higher is contained in a concentration range of 0.0001 to 0.003 mass % (see Patent Document 1, for example).

In addition, there is known a bend-resistant copper alloy wire in which indium is 0.1 to 1.0 wt %, boron is 0.02 to 0.1 wt %, and the remainder is copper (for example, refer to Patent Document 2).

In addition, FPC (Flexible Printed Circuit board, Flexible Print Circuit board), COF (Chip On film), TAB (Tape Automated Bonding), etc., are used for the installation of semiconductors and electronic equipment. In other words, copper foil for wiring is arranged on one or both surfaces of the film-like insulator. As these copper foils, rolled foils excellent in portability and bending resistance required for wiring of operating parts in the case of FPC, for example, can be used. Rolled foil is thinly stretched and manufactured by plastic working with rolls, and tough copper (TPC) and oxygen-free copper (OFC) have been used conventionally as raw materials.

prior art literature

patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2002-363668

Patent Document 2: Japanese Patent Application Laid-Open No. 9-256084

Contents of the invention

The problem to be solved by the invention

However, the invention described in Patent Document 1 is always an invention of a hard copper wire, and no specific evaluation of bending resistance has been performed, and no research has been conducted on a soft copper wire having more excellent bending resistance. In addition, since the amount of added elements is large, the electrical conductivity decreases. Regarding soft copper wires, it can be said that sufficient research has not yet been conducted. In addition, although the invention according to Patent Document 2 is an invention related to a soft copper wire, like the invention according to Patent Document 1, since the addition amount of the additive element is large, the conductivity is lowered.

On the other hand, it is conceivable to ensure high conductivity by selecting a high-conductivity copper material such as oxygen-free copper (OFC) as a copper material used as a raw material.

However, in the case of using this oxygen-free copper (OFC) as a raw material without adding other elements in order to maintain electrical conductivity, the crystal structure inside the oxygen-free copper wire can be made Thinning and improving bending resistance may also be effective, but in this case, there is a problem that it is suitable for use as hard wires but not soft wires due to work hardening due to wire drawing.

For example, when tough copper (TPC) is used for FPC, when it is bonded to a polyimide resin film and cured (heat treatment at 150 to 160°C), the copper foil is softened and recrystallized, and the bend is improved by forming a structure. characteristic. However, when oxygen-free copper (OFC) is used as the raw material, recrystallization is insufficient at the solidification temperature, and bending properties cannot be improved. On the other hand, compared with OFC and high-purity copper (99.9999%), ductile copper has poor workability in addition to poor electrical conductivity, and requires more rolling times to be processed to a predetermined thickness.

Therefore, an object of the present invention is to provide a rolled copper foil having high electrical conductivity and a high bending life even if it is a soft copper material, and a method for producing the rolled copper foil.

Solution to the problem

In order to solve the above-mentioned problems, the present invention provides a rolled copper foil containing oxygen in an amount exceeding 2 mass ppm in pure copper containing unavoidable impurities, and oxygen selected from Mg, Zr, Nb, Ca, V, Ni, An additional element in the group consisting of Mn, Ti, and Cr.

In addition, in the above-mentioned rolled copper foil, the added element is Ti, and the rolled copper foil is preferably made of sulfur containing 2 mass ppm to 12 mass ppm, exceeding 2 mass ppm to 30 mass ppm Oxygen and a soft low-concentration copper alloy material of not less than 4 mass ppm and not more than 55 mass ppm of titanium.

In addition, the above-mentioned rolled copper foil may have a semi-softening temperature of 148° C. or less in the case of a thickness of 0.8 mm.

In addition, in the above-mentioned rolled copper foil, the crystal structure before processing may have a surface layer having an average crystal grain size of 20 μm or less inward from the surface to a depth of 50 μm.

In addition, in order to solve the above-mentioned problems, the present invention provides a method of manufacturing rolled copper foil, which includes the following steps: using SCR continuous casting and rolling, at a casting temperature of 1100°C to 1320°C, the copper foil containing unavoidable impurities Made of a low-concentration copper alloy material containing oxygen in an amount exceeding 2 mass ppm in pure copper, and an additive element selected from the group consisting of Mg, Zr, Nb, Ca, V, Ni, Mn, Ti, and Cr a process of producing a copper material from the molten solution; a process of subjecting the copper material to hot rolling to produce a cast material; and a process of performing cold rolling on the cast material to produce a rolled copper foil.

In addition, in the manufacturing method of the above-mentioned rolled copper foil, the added element is Ti, and the low-concentration copper alloy material may contain 2 mass ppm to 12 mass ppm of sulfur, exceeding 2 mass ppm to 30 mass ppm Oxygen of less than 4 mass ppm and titanium of 55 mass ppm or less.

In addition, in the manufacturing method of the above-mentioned rolled copper foil, the hot rolling process can be implemented by controlling the temperature of the first roll to 880° C. or lower, and controlling the temperature of the final roll to 550° C. or higher.

Invention effect

The rolled copper foil and the manufacturing method of the rolled copper foil which concern on this invention can provide the rolled copper foil and the manufacturing method of the rolled copper foil which have high electroconductivity and a high bending life even if it is a soft copper material.

Description of drawings

Figure 1 is the SEM image of TiS particles.

FIG. 2 is a graph showing the analysis results of FIG. 1 .

Figure 3 is the SEM image of _TiO2 particles.

FIG. 4 is a graph showing the analysis results of FIG. 3 .

Fig. 5 is a SEM image of Ti-O-S particles.

FIG. 6 is a graph showing the analysis results of FIG. 5 .

Fig. 7 is a diagram showing the outline of a bending fatigue test.

Fig. 8 shows the measurement of the wire rod of Comparative Example 13 using oxygen-free copper and the soft low-concentration copper alloy wire in which Ti was added to low-oxygen copper after annealing at 400°C for 1 hour. A graph of the results obtained for the bending life of the wire rod of Example 7.

Fig. 9 shows the measurement of the wire rod of Comparative Example 14 using oxygen-free copper and the soft low-concentration copper alloy wire in which Ti was added to low-oxygen copper after annealing at 600°C for 1 hour. A graph of the results obtained for the bending life of the wire rod of Example 8.

10 is a view showing a cross-sectional structure in the width direction of a sample of Example 8. FIG.

FIG. 11 is a view showing a cross-sectional structure in the width direction of a sample of Comparative Example 14. FIG.

Fig. 12 is a schematic diagram of a method of measuring the average crystal grain size of the surface layer.

Fig. 13 is a schematic diagram showing the configuration of a testing machine for evaluating bending characteristics.

Fig. 14 is a graph showing the relationship between annealing temperature and elongation.

Symbol Description

1 conductor

2a, 2b conductor fixing part

3 Vibration attachment

4 Vibration generating device

5 Support Department

10 rings

12 Fixtures

14 bend head

16 hammers

20 samples

30 resin substrate

30a concave-convex shape

40 conductors

50 resin layers.

Detailed ways

The rolled copper foil of the present embodiment is used to satisfy an electrical conductivity of 98% IACS (International Anneld Copper Standard, the electrical conductivity when the resistivity is 1.7241×10 ^-8 Ωm as 100%) or more, preferably 100%. IACS or more, more preferably 102% IACS or more soft low-concentration copper alloy material of soft copper material.

In addition, the rolled copper foil according to the present embodiment uses SCR continuous casting equipment, has little surface damage, has a wide manufacturing range, and can be stably produced. The cast material is constructed using a material having a semi-softening temperature of 148° C. or lower at a working degree of 90%.

Specifically, the rolled copper foil of this embodiment contains oxygen in an amount exceeding 2 mass ppm in pure copper containing unavoidable impurities, and oxygen selected from Mg, Zr, Nb, Ca, V, Ni, Mn, Ti It is composed of an additional element in the group consisting of Cr and Cr. The reason for selecting elements selected from the group consisting of Ti, Mg, Zr, Nb, Ca, V, Ni, Mn, and Cr as the additive elements is that these elements are active elements that are easily combined with other elements, and because they are easily combined with Since S is bonded, S can be captured and the copper base material (substrate) can be highly purified. One or more kinds of additional elements may be contained. In addition, other elements and impurities that do not adversely affect the properties of the alloy may be contained in the alloy. In addition, in the preferred embodiment described below, it is explained that the oxygen content is more than 2 mass ppm and 30 mass ppm or less is good. It contains more than 2 mass ppm and is 400 mass ppm or less.

In addition, the additive element of the rolled copper foil may be Ti. In this case, the rolled copper foil is composed of sulfur containing 2 mass ppm to 12 mass ppm, oxygen exceeding 2 mass ppm to 30 mass ppm, and 4 It is composed of a soft low-concentration copper alloy material of titanium in mass ppm to 55 mass ppm. Furthermore, the rolled copper foil preferably has a half softening temperature of 137° C. or less in a dimension having a thickness of 0.8 mm. Since oxygen is contained in excess of 2 mass ppm to 30 mass ppm or less, so-called low-oxygen copper (LOC) is targeted in this embodiment.

In addition, the rolled copper foil of this embodiment is manufactured through the following process. First, by using SCR continuous casting and rolling, at a casting temperature of 1100°C to 1320°C, pure copper containing unavoidable impurities contains 2 mass ppm or more of oxygen, and oxygen selected from Mg, Zr, Nb, Ca, A low-concentration copper alloy material with added elements in the group consisting of V, Ni, Mn, Ti, and Cr is made into a melt. Copper is then made from the melt. Next, the obtained copper material was subjected to hot rolling processing to produce a cast material. Then, the cast material is subjected to cold rolling processing to manufacture the rolled copper foil of this embodiment.

In addition, the hot rolling process is preferably carried out by controlling the temperature at the first roll to 880°C or lower and controlling the temperature at the final roll to 550°C or higher.

Hereinafter, the contents studied by the present inventors will be described for realization of the rolled copper foil of the present embodiment.

First, high-purity copper with a purity of 6N (ie, 99.9999%) has a semi-softening temperature of 130° C. at a processing degree of 90%. Therefore, at a semi-softening temperature of 130°C to 148°C that can be stably produced, soft materials with an electrical conductivity of 98% IACS or higher, preferably 100% IACS or higher, more preferably 102% IACS or higher, can be stably produced. The inventors of the present invention conducted studies on a soft low-copper alloy material of copper and a method for producing the soft low-copper alloy material.

Here, high-purity copper (4N) having an oxygen concentration of 1 to 2 mass ppm was prepared, and this Cu was made into a Cu melt using a small continuous casting machine (small continuous casting machine) installed in a laboratory. Then, several mass ppm of titanium was added to the melt. Next, a φ8 mm wire rod was produced from the titanium-added melt. Next, the φ8mm wire rod was processed to φ2.6mm (that is, the processing degree was 90%). The semi-softening temperature of the φ2.6 mm wire rod is 160° C. to 168° C., and a half-softening temperature lower than this temperature is unacceptable. In addition, the electrical conductivity of this φ2.6 mm wire rod is about 101.7% IACS. That is to say, the present inventors obtained the following knowledge: Even if the oxygen concentration contained in the wire rod is reduced, and titanium is added to the melt, the semi-softening temperature of the wire rod cannot be lowered, and the electrical conductivity is lower than that of high-purity copper (6N) The electrical conductivity is 102.8% IACS.

The reason why high-purity copper whose half-softening temperature cannot be lowered and whose electrical conductivity is lower than 6N is presumed to be that it contains sulfur (S) of several mass ppm or more as an unavoidable impurity in the manufacture of molten metal. That is, it is presumed that the semi-softening temperature of the wire rod did not decrease because sulfides such as TiS were not sufficiently formed between sulfur contained in the melt and titanium.

Therefore, in order to lower the semi-softening temperature of the soft low-concentration copper alloy material and improve the electrical conductivity of the soft low-concentration copper alloy material, the present inventors studied the following two proposals. And the soft low-concentration copper alloy material which comprises the rolled copper foil of this embodiment was obtained by using the following two aspects together for manufacture of a copper wire rod.

FIG. 1 is a SEM image of TiS particles, and FIG. 2 shows the analysis results of FIG. 1 . In addition, FIG. 3 is a SEM image of TiO ₂ particles, and FIG. 4 shows the analysis results of FIG. 3 . In addition, FIG. 5 is a SEM image of Ti-OS particles, and FIG. 6 shows the analysis results of FIG. 5 . In addition, in the SEM image, each particle near the center was photographed. Fig. 1～6 is by SEM observation and EDX analysis to evaluate the cross-section of the copper wire (wire rod) having the oxygen concentration, sulfur concentration, Ti concentration of the third section of the upper third section of the oxygen concentration, sulfur concentration, and Ti concentration of Example 1 shown in Table 1. Got the picture. Observation conditions were set at an accelerating voltage of 15 keV and an emission current of 10 μA.

First, in the first aspect, a Cu melt is produced in a state in which titanium (Ti) is added to Cu having an oxygen concentration exceeding 2 mass ppm. In this melt, TiS, titanium oxide (for example, TiO ₂ ), and Ti—OS particles are considered to be formed. This is a review from the SEM image of FIG. 1 and the analysis results of FIG. 2 , the SEM image of FIG. 3 and the analysis results of FIG. 4 . In addition, in FIG. 2 , FIG. 4 , and FIG. 6 , Pt and Pd are metal elements vapor-deposited on the observation object during SEM observation.

Next, in the second scheme, the temperature during the hot rolling process is set at a temperature higher than the usual copper production conditions (that is, 950° C. to 600° C.) for the purpose of easily precipitating sulfur (S) by introducing dislocations into copper. °C) lower temperature (880 °C ~ 550 °C). By setting such a temperature, S can be precipitated on dislocations, or S can be precipitated using titanium oxide (for example, TiO ₂ ) as a nucleus. As an example, as shown in FIGS. 5 and 6 , Ti—OS particles and the like are formed together with molten copper.

According to the above first and second aspects, the sulfur contained in the copper is crystallized and precipitated, so that a copper wire rod having a desired semi-softening temperature and a desired electric conductivity can be obtained after cold wire drawing.

In addition, the soft low-concentration copper alloy material constituting the rolled copper foil of this embodiment is produced using SCR continuous casting and rolling equipment. Here, the following three conditions are set as restrictions on manufacturing conditions when using the SCR continuous casting and rolling facility.

(1) Regarding composition

In order to obtain a soft copper material with an electrical conductivity of 98% IACS or more, as pure copper (basic raw material) containing unavoidable impurities, use sulfur containing 3 to 12 mass ppm, more than 2 mass ppm and 30 mass ppm A soft low-concentration copper alloy material of the following oxygen and 4 to 55 mass ppm of titanium is used to manufacture a wire rod (wire stock) from the soft low-concentration copper alloy material.

Here, in the case of obtaining a soft copper material having an electrical conductivity of 100% IACS or more, as pure copper (basic raw material) containing unavoidable impurities, sulfur containing 2 to 12 mass ppm, exceeding 2 mass ppm and 30 A soft low-concentration copper alloy material consisting of oxygen at mass ppm or less and titanium at 4 to 37 mass ppm. In addition, in the case of obtaining a soft copper material with an electrical conductivity of 102% IACS or more, as pure copper (basic raw material) containing unavoidable impurities, sulfur containing 3 to 12 mass ppm, exceeding 2 mass ppm and 30 A soft low-concentration copper alloy material consisting of oxygen at mass ppm or less and titanium at 4 to 25 mass ppm.

Generally, in the industrial production of pure copper, since sulfur is introduced into copper during the production of electrolytic copper, it is difficult to keep sulfur at 3 mass ppm or less. The upper limit of the sulfur concentration of general-purpose electrolytic copper is 12 mass ppm.

When the oxygen concentration is low, it is difficult to lower the semi-softening temperature of the soft low-concentration copper alloy material constituting the rolled copper foil, so the oxygen concentration is controlled to exceed 2 mass ppm. In addition, when the oxygen concentration is high, damage is likely to occur on the surface of the soft low-concentration copper alloy material constituting the rolled copper foil in the hot rolling process, so it is controlled to be 30 mass ppm or less.

(2) Regarding dispersed substances

The size of the dispersed particles dispersed in the soft low-concentration copper alloy material constituting the rolled copper foil is preferably small, and it is preferable that a large number of dispersed particles are dispersed in the soft low-concentration copper alloy material constituting the rolled copper foil. The reason for this is that the dispersed particles function as precipitation sites of sulfur, and the precipitation sites are required to be small in size and large in number.

Sulfur and titanium contained in soft low-concentration copper alloy materials constituting rolled copper foil as TiO, TiO ₂ , TiS or compounds with Ti-OS bonds, or TiO, TiO ₂ , TiS or compounds with Ti-OS bonds Condensates of compounds are contained, and the remainder of Ti and S are contained as solid solutions. As the soft low-concentration copper alloy material constituting the rolled copper foil, TiO has a size of 200nm or less, TiO ₂ has a size of 1000nm or less, TiS has a size of 200nm or less, and a compound in the form of Ti-OS has a size of 300nm or less. , and they are distributed in the soft low-concentration copper alloy material in the grain.

In addition, since the size of the particles formed in the crystal grains changes depending on the retention time and cooling conditions of the molten copper during casting, the casting conditions are also appropriately set.

(3) Regarding casting conditions

SCR continuous casting and rolling is used to make wire rods with a processing degree of 90% (30mm) to 99.8% (5mm). As an example, the conditions for manufacturing a wire rod of φ8 mm at a working degree of 99.3% are employed. Hereinafter, the casting conditions (a) to (b) will be described.

[Casting condition (a)]

The molten copper temperature in the melting furnace is controlled above 1100°C and below 1320°C. When the temperature of molten copper is high, pores tend to increase, damage occurs, and the particle size tends to increase, so it is controlled at 1320°C or lower. In addition, the reason for controlling at 1100° C. or higher is that copper is easy to solidify and production is unstable, but the molten copper temperature is preferably as low as possible.

[Casting condition (b)]

As for the temperature of the hot rolling process, the temperature of the initial roll is controlled below 880°C, and the temperature of the final roll is controlled above 550°C.

Unlike normal pure copper production conditions, in order to further reduce the solid solution limit, which is the driving force for the crystallization of sulfur in molten copper and the precipitation of sulfur in hot rolling, it is preferable to set the temperature of molten copper and the temperature of hot rolling to Set the conditions described in [Casting Conditions (a)] and [Casting Conditions (b)].

In addition, the temperature of the usual hot rolling process is 950° C. or lower in the first roll, and 600° C. or higher in the final roll. However, in order to further reduce the solid solution limit, in this embodiment, the first roll Set to 880°C or lower, and set to 550°C or higher in the final roll.

In addition, the reason why the temperature of the final roll is set at 550°C is that the damage of the wire rod obtained at a temperature lower than 550°C increases, and the soft low-concentration copper constituting the rolled copper foil produced cannot be removed. Alloy materials are used as products. Regarding the temperature of the hot rolling process, the temperature of the initial roll is controlled at 880° C. or lower, and the temperature of the final roll is controlled at 550° C. or higher, and the temperature is preferably as low as possible. By setting such a temperature, the semi-softening temperature of the soft low-concentration copper alloy material constituting the rolled copper foil (the semi-softening temperature after processing to φ8-φ2.6mm) can be close to the semi-softening temperature of 6N Cu ( ie 130°C).

The electrical conductivity of oxygen-free copper is about 101.7% IACS, and the electrical conductivity of 6N Cu is 102.8% IACS. In the present embodiment, for example, the electrical conductivity of the wire rod having a diameter of φ8 mm is 98% IACS or higher, preferably 100% IACS or higher, more preferably 102% IACS or higher. In addition, in the present embodiment, a soft low-concentration copper alloy having a semi-softening temperature of the wire rod (for example, φ2.6mm) after cold drawing is produced from 130° C. to 148° C. High-quality low-concentration copper alloys are used in the manufacture of rolled copper foil.

For industrial use, an electrical conductivity of 98% IACS or higher is required as an electrical conductivity of an industrially usable pure soft copper wire made of electrolytic copper. In addition, judging from the industrial value, the half-softening temperature is 148° C. or lower. Since the half-softening temperature of 6N Cu is 127°C to 130°C, the upper limit of the half-softening temperature is set to 130°C from the obtained data. This slight difference is due to the presence of unavoidable impurities not contained in 6N Cu.

The copper of the base material is preferably melted in the shaft furnace and flows through the trough in a reduced state. That is, it is preferable to cast the low-concentration copper alloy while controlling the sulfur concentration, titanium concentration, and oxygen concentration in a reducing system such as a reducing gas (such as CO) atmosphere barrier, and to perform rolling processing on the material to stably manufacture the wire rod . In addition, the incorporation of copper oxides and/or particle size larger than a predetermined size will lower the quality of the produced rolled copper foil.

Here, the reason why titanium is added as an additive to the soft low-concentration copper alloy material constituting the rolled copper foil is as follows. That is, because (a) titanium is easily combined with sulfur in molten copper to form a compound; (b) compared with other metals such as Zr, it is easy to process and handle; (c) it is cheaper than Nb, etc.; (d) it is easy to Precipitate with oxide as the nucleus.

From the above, a practical soft low-concentration copper alloy material with high productivity and excellent electrical conductivity, semi-softening temperature, and surface quality can be obtained as a raw material for the soft low-concentration copper alloy material constituting the rolled copper foil of this embodiment. In addition, a plated layer may also be formed on the surface of the soft low-concentration copper alloy material. For the plating layer, for example, a material mainly composed of tin, nickel, or silver, or Pb-free plating can be used.

In addition, in this embodiment, the wire rod is produced by the SCR continuous casting and rolling method, and the soft material is produced by hot rolling, but the twin-roll continuous casting and rolling method or the Propez continuous casting and rolling method may also be used. method.

(Effect of embodiment)

In the rolled copper foil in this embodiment, added Ti captures S as an impurity, and the copper matrix (matrix) is purified and softened. That is, it can be processed to a predetermined thickness with fewer rolling times or a lower rolling load, and the workability is excellent. In addition, the copper foil can be softened and recrystallized by heat treatment (150 to 160° C.) at the time of curing, thereby improving bending characteristics.

Moreover, the rolled copper foil in this embodiment has high electroconductivity and has a high bending life. In other words, the rolled copper foil combines these excellent properties (workability, softening at low temperature, high bending properties, high electrical conductivity), thereby achieving operational efficiency in the manufacture of rolled copper foil and in product assembly , Cost reduction. In addition, since it can be obtained by an inexpensive continuous casting and rolling method without the need for high-purity (99.9999%) copper, it is possible to reduce the cost of the raw material itself. These uses are not limited to the above-mentioned FPC, COF, TAB, etc., but can be widely applied to copper foils and the like used for electrodes of lithium ion batteries, lithium polymer batteries, and the like.

Example

Table 1 shows the experimental conditions and results.

Table 1

First, as test materials, φ8mm copper wires (wire rods, processing degree 99.3%) having the oxygen concentrations, sulfur concentrations, and titanium concentrations shown in Table 1 were produced. The φ8mm copper wire was hot-rolled by SCR continuous casting and rolling. As for Ti, molten copper melted in a shaft furnace is passed through a tank in a reducing gas atmosphere, and the molten copper that has flowed through the tank is introduced into a casting tank with the same reducing gas atmosphere, and in the casting tank, added After Ti, it is passed through the nozzle, using the mold formed between the casting ring and the annular belt to make the cast strip. This cast bar was hot-rolled to produce a φ8 mm copper wire. Next, cold wire drawing was performed on each test material. Thus, a copper wire having a size of φ2.6 mm was produced. Then, the half-softening temperature and electrical conductivity of the φ2.6 mm-sized copper wire were measured, and the dispersed particle size in the φ8 mm copper wire was evaluated.

The oxygen concentration was measured with an oxygen analyzer (Leco (registered trademark) oxygen analyzer). Each concentration of sulfur and titanium was analyzed by ICP emission spectroscopic analysis.

The half-softening temperature of the diameter of φ2.6mm is measured by holding at each temperature below 400°C for 1 hour, quenching in water, performing a tensile test, and obtaining it from the result. It is obtained using the results of the tensile test at room temperature and the result of the tensile test of soft copper wire subjected to an oil bath heat treatment at 400°C for 1 hour, and the tensile test obtained by these two tensile tests The temperature corresponding to the value obtained by dividing the strength by 2 after adding the strength was defined as the half-softening temperature and obtained.

As described in the embodiment, it is preferable that the size of the dispersed particles dispersed in the soft low-concentration copper alloy wire is small, and it is preferable that a large number of dispersed particles be dispersed in the soft low-concentration copper alloy wire. Therefore, the case where 90% or more of the dispersed particles with a diameter of 500 nm or less was considered acceptable. Here, the "size" refers to the size of the compound, and refers to the size of the major axis among the major axis and the minor axis of the shape of the compound. In addition, "particle" means the aforementioned TiO, TiO ₂ , and Ti-OS. In addition, "90%" represents the ratio of the particle number to the whole particle number.

In Table 1, Comparative Example 1 is the result of trial production of a copper wire with a diameter of φ8 mm in an Ar atmosphere in a laboratory, and 0 to 18 mass ppm of Ti was added to the copper melt. The semi-softening temperature of the copper wire to which Ti was not added was 215° C., but that of the copper wire to which 13 mass ppm of Ti was added decreased to 160° C. (minimum temperature in the experiment). As shown in Table 1, as the Ti concentration increased to 15 mass ppm and 18 mass ppm, the half-softening temperature also increased, and the required half-softening temperature of 148° C. or lower could not be achieved. In addition, although the industrially required electrical conductivity was 98% IACS or higher, the overall evaluation was unacceptable (hereinafter, unacceptable is indicated by "x").

Therefore, as Comparative Example 2, a φ8 mm copper wire (wire rod) in which the oxygen concentration was adjusted to 7 to 8 mass ppm was trial-manufactured using the SCR continuous casting and rolling method.

In Comparative Example 2, among the copper wires trial-produced by the SCR continuous casting and rolling method, the copper wire with the smallest Ti concentration (that is, 0 mass ppm, 2 mass ppm) had an electrical conductivity of 102% IACS or more, but because The half-softening temperature was 164°C and 157°C, but not below the required 148°C, so the comprehensive evaluation was "×".

In Example 1, the oxygen concentration and the sulfur concentration were substantially the same (that is, the oxygen concentration: 7 to 8 mass ppm, the sulfur concentration: 5 mass ppm), and the Ti concentration was in the range of 4 to 55 mass ppm. Wire.

The Ti concentration is in the range of 4 to 55 mass ppm, the half-softening temperature is 148° C. or less, the electrical conductivity is also 98% IACS or more and 102% IACS or more, and the particles with a dispersed particle size of 500 nm or less are 90% or more, which is good. In addition, the surface of the wire rod was also clean and satisfied all the product properties, so the comprehensive evaluation was passed (hereinafter, “◯” indicates pass).

Here, the copper wire satisfying the electrical conductivity of 100% IACS or higher has a Ti concentration of 4 to 37 mass ppm, and the copper wire satisfying 102% IACS or higher has a Ti concentration of 4 to 25 mass ppm. When the Ti concentration was 13 mass ppm, the electrical conductivity showed a maximum value of 102.4% IACS, and the electrical conductivity was a slightly lower value around this concentration. This is because, when the Ti concentration is 13 mass ppm, the sulfur component in copper is captured as a compound, thereby exhibiting electrical conductivity close to that of high-purity copper (6N).

Therefore, by increasing the oxygen concentration and adding Ti, both the half-softening temperature and the electrical conductivity can be satisfied.

In Comparative Example 3, a copper wire having a Ti concentration of 60 mass ppm was trial-produced. Although the electrical conductivity of the copper wire of Comparative Example 3 meets the requirements, the semi-softening temperature is above 148° C., which does not meet the product performance. In addition, the surface of the wire rod has many damages, making it difficult to use it as a product. Therefore, it was shown that the addition amount of Ti is preferably less than 60 mass ppm.

Regarding the copper wire of Example 2, the sulfur concentration was set at 5 mass ppm and the Ti concentration was controlled within the range of 13 to 10 mass ppm, and the influence of the oxygen concentration was studied by changing the oxygen concentration.

Regarding the oxygen concentration, copper wires having a large concentration difference from more than 2 mass ppm to 30 mass ppm or less were produced. However, copper wires with an oxygen concentration of less than 2 mass ppm were difficult to produce stably, so the overall evaluation was "△" ("△" is an intermediate evaluation between "◯" and "×"). In addition, even if the oxygen concentration was set to 30 mass ppm, both the half-softening temperature and the electrical conductivity were satisfactory.

In Comparative Example 4, when the oxygen concentration was 40 mass ppm, the surface of the wire rod had many damages, and it was in a state where it could not be used as a product.

Therefore, by making the oxygen concentration more than 2 and being in the range of 30 mass ppm or less, it can be shown that the semi-softening temperature, the electrical conductivity of 102% IACS or more, and the dispersed particle size can be satisfied, and the surface of the wire rod is also clean. Can meet product performance.

Example 3 is a copper wire in which the oxygen concentration and the Ti concentration are set to be close to each other, and the sulfur concentration is varied within the range of 2 to 12 mass ppm. In Example 3, regarding the copper wire with a sulfur concentration of less than 2 mass ppm, it was not possible due to constraints on raw materials. However, by separately controlling the Ti concentration and the sulfur concentration, both the half-softening temperature and the electrical conductivity can be satisfied.

In Comparative Example 5, when the sulfur concentration was 18 mass ppm and the Ti concentration was 13 mass ppm, the half-softening temperature was as high as 162° C., which did not satisfy the required characteristics. In addition, in particular, the surface quality of the wire rod is poor, and it is difficult to commercialize it.

From the above, when the sulfur concentration is in the range of 2 to 12 mass ppm, any of the characteristics of the half-softening temperature, the electrical conductivity of 102% IACS or more, and the size of the dispersed particles can be satisfied, and the surface of the wire rod is also clean, which can satisfy Product performance.

Comparative example 6 is a copper wire using 6N Cu. In the copper wire of Comparative Example 6, the semi-softening temperature was 127° C. to 130° C., the electrical conductivity was 102.8% IACS, and particles having a dispersed particle size of 500 or less were not found at all.

Table 2 shows the temperature of molten copper and the rolling temperature as production conditions.

Table 2

In Comparative Example 7, a wire rod having a diameter of 8 mm was produced at a molten copper temperature of 1330°C to 1350°C and a rolling temperature of 950°C to 600°C. In the wire rod of Comparative Example 7, although the semi-softening temperature and electrical conductivity meet the requirements, there are particles with a size of about 1000 nm in the dispersed particle size, and more than 10% of particles with a size of 500 nm or more are present. Therefore, it was judged that the wire rod of Example 7 was not suitable.

In Example 4, the molten copper temperature was controlled in the temperature range of 1200° C. to 1320° C. and the rolling temperature was controlled in the temperature range of 880° C. to 550° C. to produce a φ8 mm wire rod. In the wire rod of Example 4, the quality of the wire rod surface and the size of the dispersed particles were good, and the overall evaluation was "◯".

In Comparative Example 8, the molten copper temperature was controlled at 1100° C., and the rolling temperature was controlled within a temperature range of 880° C. to 550° C. to produce a φ8 mm wire rod. In the wire rod of Comparative Example 8, since the molten copper temperature was low, there were many damages on the surface of the wire rod, and it was not suitable as a product. This is because the temperature of molten copper is low, so damage is likely to occur during rolling.

In Comparative Example 9, the molten copper temperature was controlled at 1300° C., and the rolling temperature was controlled within a temperature range of 950° C. to 600° C. to produce a φ8 mm wire rod. In the wire rod of Comparative Example 9, since the temperature in the hot rolling process was high, the surface quality of the wire rod was good, but the dispersed particle size included large ones, and the overall evaluation was "x".

In Comparative Example 10, the molten copper temperature was controlled at 1350° C., and the rolling temperature was controlled within a temperature range of 880° C. to 550° C. to produce a φ8 mm wire rod. In the wire rod of Comparative Example 10, since the molten copper temperature was high, the dispersed particle size included large ones, and the overall evaluation was "x".

(Soft characteristics of soft low-concentration copper alloy wire)

Table 3 shows the wire rod of Comparative Example 11 using an oxygen-free copper wire and the wire rod of Example 5 produced from a soft low-concentration copper alloy wire containing 13 mass ppm of Ti in low-oxygen copper. The results of Vickers hardness (Hv) after annealing for 1 hour at the annealing temperature.

table 3

(Unit: Hv)

The wire rod of Example 5 had the same alloy composition as that described in Example 1 in Table 1. In addition, as a sample, a sample with a diameter of 2.6 mm was used. Referring to Table 3, the Vickers hardness of the wire rod of Comparative Example 11 and the wire rod of Example 5 are at the same level when the annealing temperature is 400°C and 600°C. Therefore, the wire rod of Example 5 has sufficient soft properties, and exhibits excellent soft properties especially in the temperature range where the annealing temperature exceeds 400° C., compared with the oxygen-free copper wire.

(Research on yield strength and bending life of soft low-concentration copper alloy wire)

Table 4 shows the wire rod of Comparative Example 12 using an oxygen-free copper wire and the wire rod of Example 6 produced using a soft low-concentration copper alloy wire containing 13 mass ppm of Ti in low-oxygen copper. The results of the change of the 0.2% yield strength value after annealing for 1 hour at different annealing temperatures.

Table 4

(Unit: MPa)

Referring to Table 4, it can be seen that the 0.2% yield strength values of the wire rod of Comparative Example 12 and the wire rod of Example 6 are at the same level when the annealing temperature is 400°C and 600°C.

Fig. 7 shows the outline of the bending fatigue test, and Fig. 8 shows the measurement of the wire rod of Comparative Example 13 using oxygen-free copper after annealing at 400°C for 1 hour and the wire rod of Comparative Example 13 using low-oxygen copper with Ti added. The results of the bending life of the wire rod of Example 7 fabricated from a low-concentration copper alloy wire.

As a sample, a sample obtained by annealing a wire rod with a diameter of 0.26 mm at an annealing temperature of 400° C. for 1 hour was used. The wire rod of Comparative Example 13 had the same composition as that of the wire rod of Comparative Example 11. Example The wire rod of 7 has the same composition as that of the wire rod of Example 5.

The measurement of the bending life was carried out using a bending fatigue test. The bending fatigue test is a test of the repeated bending strain of the load on the sample and the tension and compression of the surface of the sample. Specifically, first, as shown in FIG. 7(A), the sample 20 is fixed to the jig 12 included in the bending head 14, and the sample 20 is set between the bending jigs (that is, the ring 10). Then, a load is applied to the sample 20 by the hammer 16 . Next, as shown in FIG. 7(B), the sample 20 is bent by rotating the ring 10 by 90 degrees. Through this operation, compressive strain is generated on the surface of the sample 20 in contact with the ring 10, and tensile strain is generated on the surface opposite to the surface where the compressive strain is generated.

Thereafter, the sample 20 returns to the state of FIG. 7(A) again (that is, the state where bending is not applied to the sample 20 ). Next, as shown in FIG. 7(C), the sample 20 is bent by rotating the ring 10 by 90 degrees in a direction opposite to that of FIG. 7(B). Through this operation, compressive strain is generated on the surface of the sample 20 in contact with the ring 10, and tensile strain is generated on the surface opposite to the surface where the compressive strain is generated. Then, the sample 20 returns to the state of FIG. 7(A) again. One cycle of this bending fatigue (that is, changing from the state of Fig. 7(A) to the state of (B), returning from the state of (B) to the state of (A), changing from the state of (A) to ( The state of C) and the cycle from the state of (C) back to the state of (A) are regarded as one cycle.) The time required is 4 seconds.

The surface bending strain was calculated from "surface bending strain (%)=r/(R+r)×100(%)". In addition, "R" is a wire bending radius (30mm), and "r" is a wire radius.

As shown in FIG. 8 , compared with the wire rod of Comparative Example 13, the wire rod of Example 7 exhibited high bending life characteristics.

Fig. 9 shows the measurement of the wire rod of Comparative Example 14 using oxygen-free copper after annealing treatment at 600°C for 1 hour and the wire rod made by using a soft low-concentration copper alloy wire in which Ti was added to low-oxygen copper. The results of the bending life of the wire rod of Example 8.

As a sample, a sample obtained by annealing a wire rod with a diameter of 0.26 mm at an annealing temperature of 600° C. for 1 hour was used. The wire rod of Comparative Example 14 had the same composition as that of the wire rod of Comparative Example 11. The wire rod of 8 has the same composition as that of the wire rod of Example 5. In addition, the measurement of the bending life was carried out in the same manner as the measurement method shown in FIG. 8 . As a result, compared with the wire rod of Comparative Example 14, the wire rod of Example 8 exhibited higher bending life characteristics.

The results of the bending life measurement of the wire rods of embodiment 7, embodiment 8, comparative example 13 and comparative example 14 can be understood because: under any annealing conditions, the wire rods of embodiment 7 and embodiment 8 are the same as those of comparative examples 13 and Compared with the wire rod of Comparative Example 14, all of the 0.2% proof stress values showed larger values.

(Research on the crystal structure of soft low-concentration copper alloy wire)

FIG. 10 shows the cross-sectional structure in the width direction of the sample of Example 8. FIG. Fig. 11 shows the cross-sectional structure in the width direction of the sample of Comparative Example 14,

Referring to FIG. 11 , in the crystal structure of Comparative Example 14, crystal grains of equal size are uniformly arranged from the surface portion to the central portion as a whole. On the other hand, in the crystal structure of Example 8, the size of the crystal grains is uneven as a whole, and the crystal grain size in the layer formed thinly near the surface in the cross-sectional direction of the sample is greatly larger than the internal crystal grain size. reduced.

The inventors of the present invention believe that the appearance of the fine grain layer in the surface layer not formed in Comparative Example 14 contributes to the improvement of the bending characteristics of Example 8.

It is generally understood that if the annealing treatment is performed at an annealing temperature of 600° C. for 1 hour, coarse grains are uniformly formed by recrystallization as in Comparative Example 14. However, in this example, even if the annealing treatment was performed at an annealing temperature of 600° C. for 1 hour, the fine crystal grain layer remained on the surface layer. Therefore, in the present example, it is considered that a soft low-concentration copper alloy material having excellent bending characteristics can be obtained although it is a soft copper material.

In addition, the average crystal grain size in the surface layer of the samples of Example 8 and Comparative Example 14 was measured based on the cross-sectional photographs of the crystal structures shown in FIGS. 10 and 11 .

Fig. 12 shows an outline of a method of measuring the average crystal grain size in the surface layer.

As shown in FIG. 12 , the crystal grain size was measured on a line of length 1 mm from the surface of the cross-section in the width direction with a diameter of 0.26 mm to a depth of 50 μm at intervals of 10 μm along the depth direction. Then, the average value was calculated|required from each measured value (actual measurement value), and this average value was made into the average grain size.

As a result of the measurement, the average crystal grain size of the surface layer of Comparative Example 14 was 50 μm, whereas the average crystal grain size of the surface layer of Example 8 was 10 μm, showing a large difference. It can be considered that since the average grain size of the surface layer is small, the development of cracks caused by the bending fatigue test can be suppressed, and the bending fatigue life is prolonged (that is, when the grain size is large, cracks develop along the grain boundaries. However, due to When the grain size is small, the development direction of cracks changes, so the development can be suppressed.). As described above, this is considered to be the reason for the large difference in bending characteristics between the comparative example and the example.

In addition, regarding the average crystal grain size in the surface layer of Example 7 and Comparative Example 13 with a diameter of 2.6 mm, the range of length 10 mm at a depth of 50 μm from the surface of the cross-section in the width direction with a diameter of 0.26 mm in the depth direction was measured. internal grain size.

As a result of the measurement, the average crystal grain size in the surface layer of Comparative Example 13 was 100 μm, whereas the average crystal grain size in the surface layer of Example 7 was 20 μm.

In order to achieve the effect of this example, the upper limit of the average crystal grain size of the surface layer is preferably 20 μm or less. In addition, considering the limit value on manufacture, it is preferable that it is an average particle size of 5 micrometers or more.

Table 5 shows the temperature of molten copper and the rolling temperature as manufacturing conditions when producing a sheet material with a width of 200 mm×8 mm by changing the molten copper temperature and rolling temperature by SCR continuous casting and rolling.

table 5

The semi-softening temperature and electrical conductivity were evaluated by using a material cold-rolled from a thickness of 8 mm to 0.8 mm as a sample.

In Comparative Example 15, the molten copper temperature was controlled at 1330 to 1350° C., and the rolling temperature was controlled at 950 to 600° C. to manufacture a flat plate. The raw material of Comparative Example 15 has a satisfactory half-softening temperature and electrical conductivity, but the size of the dispersed particles also has particles of about 1000 nm, and more than 10% of the particles are 500 nm or more. Therefore, its overall evaluation was unsuitable ("X").

In Example 9, the molten copper temperature was controlled at 1200-1320° C., the rolling temperature was controlled at 880-550° C., and a flat plate was produced as a trial. Regarding the raw material of Example 9, both the surface quality of the board and the size of the dispersed particles were good, and the overall evaluation was "◯". In addition, in the raw material with a thickness of 0.8 mm, as in Example 8, there was a surface layer with an average crystal grain size of 20 μm or less from the surface inward to a depth of 50 μm.

In Comparative Example 16, the molten copper temperature was controlled at 1100° C., and the rolling temperature was controlled at 880 to 550° C. to produce a flat plate. The raw material of Comparative Example 16 was unsuitable as a product because the temperature of the molten copper was low, so the surface of the plate was damaged a lot. This is because the temperature of molten copper is low, so damage is likely to occur during rolling.

In Comparative Example 17, the molten copper temperature was controlled at 1300° C., and the rolling temperature was controlled at 950 to 600° C. to produce a flat plate. Regarding the raw material of Comparative Example 17, since the hot rolling temperature was high, the surface quality of the sheet was good, but there were particles with large dispersed particle sizes, and the overall evaluation was "x".

In Comparative Example 18, the molten copper temperature was controlled at 1350° C., and the rolling temperature was controlled at 880 to 550° C. to produce a flat plate. In the raw material of Comparative Example 18, since the molten copper temperature was high, there were particles having a large dispersed particle size, and the overall evaluation was "x".

The 8 mm-thick material of Example 9 shown in Table 5 was processed into a foil shape with a thickness of 20 μm by cold rolling to obtain a rolled copper foil of Example 10. Table 6 shows the copper foil of Comparative Example 19 composed of high-purity copper (6N) and the copper foil of Comparative Example 20 composed of tough copper (TPC) that were finished to the same size by the same processing and heat treatment as in Example 10. Foil and the copper foil of Comparative Example 21 made of oxygen-free copper (OFC), and the results of comparing and evaluating the characteristics of the copper foil.

Table 6

The workability was evaluated by the number of rolling times when the thickness was 0.8mm, heat treated at one end at 600°C for 1 hour, and then cold-rolled to a thickness of 200μm. Among the four materials, the first two with the fewest rolling times were evaluated as " ○". Bending characteristics were evaluated using a testing machine shown in FIG. 13 . In addition, the testing machine is equipped with a vibration adding part 3 for applying vibration to the conductor 1, a conductor fixing part 2a and a conductor fixing part 2b for fixing the conductor, a vibration generating device 4 for applying vibration to the vibration adding part 3, and a support for supporting the vibration generating device 4. part 5.

The test conditions are set as follows: the width of the test piece is 12mm, the length of the test piece is 200mm, the radius of curvature r=3mm, and the vibration stroke is 10mm. The case where the number of times of bending until fracture was 1×10 ⁴ or more was regarded as “◯”, and the case where it was less than 1×10 ⁴ times was regarded as “×”.

FIG. 14 shows the results of evaluating the elongation with respect to the annealing temperature of Example 10 and Comparative Example 21. FIG.

As shown in Table 6, the workability of Example 10 is superior to that of Comparative Example 21, which can be judged from exhibiting excellent elongation characteristics in a wide range from annealing temperature 100°C to 900°C. In addition, it can be seen from the comprehensive judgment of the results in Table 6 that the material of Example 10 exhibited the most excellent characteristics.

The embodiments and examples of the present invention have been described above, but the above-described embodiments and examples do not limit the invention according to the scope of the claims. In addition, it should be noted that all combinations of the features described in the embodiments and examples are not necessarily essential to means for solving the problems of the invention.

Claims (7)

1. a rolled copper foil contains the oxygen of the amount that surpasses 2 quality ppm and is selected from the interpolation element in the group of being made up of Mg, Zr, Nb, Ca, V, Ni, Mn, Ti and Cr in containing the fine copper of unavoidable impurities.

2. rolled copper foil as claimed in claim 1; Said interpolation element is Ti, and said rolled copper foil by contain the sulphur below the 12 quality ppm more than the 2 quality ppm, surpass 2 quality ppm and be below the 30 quality ppm oxygen and more than the 4 quality ppm the soft lower concentration Cu alloy material of the titanium below the 55 quality ppm constitute.

3. rolled copper foil as claimed in claim 2, semi-softening temperature is below 148 ℃ when the size of thickness 0.8mm.

4. like each described rolled copper foil in the claim 1～3, it is the top layer below the 20 μ m until the average grain size of the degree of depth of 50 μ m that the crystal structure before the processing has from its surface to inside.

5. the method for manufacture of a rolled copper foil possesses following operation:

Utilize the SCR continuous casting rolling; Under the casting temp below 1320 ℃ more than 1100 ℃, oxygen that contains the amount that surpasses 2 quality ppm in the fine copper that is containing unavoidable impurities and the lower concentration Cu alloy material that is selected from the interpolation element in the group of being made up of Mg, Zr, Nb, Ca, V, Ni, Mn, Ti and Cr are processed liquation, and make the operation of copper material by said liquation;

Thereby said copper material is implemented the operation that cast material is made in hot rolling processing; With

Thereby said cast material is implemented the operation that rolled copper foil is made in cold rolling processing.

6. the method for manufacture of rolled copper foil as claimed in claim 5,

Said interpolation element is Ti,

Said lower concentration Cu alloy material contains sulphur below the above 12 quality ppm of 2 quality ppm, surpass 2 quality ppm and be oxygen and the titanium below the above 55 quality ppm of 4 quality ppm below the 30 quality ppm.

7. the method for manufacture of rolled copper foil as claimed in claim 6, said hot rolling processing through the temperature with initial roll place be controlled at below 880 ℃, with the temperature at final roll place be controlled at 550 ℃ with on implement.

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