JP2014102996A - Method of joining soft dilute copper alloy wire to connection terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a soft dilute copper alloy wire having high conductivity and a high flex life, which can suppress disconnection during usage in comparison with an oxygen-free copper wire and can be ultrasonically connected to a connection terminal, and a method of joining the soft dilute copper alloy wire to the connection terminal.SOLUTION: The method includes the steps for: manufacturing a soft dilute copper alloy wire 11 by drawing a soft dilute copper alloy material containing an additive element easily bonded to S such as copper, Ti, or the like at a processing degree of 90% or higher and applying annealing to it, and by annealing a roughly drawn wire the average crystal grain size of which is 20 μm or smaller in a surface layer formed from the surface thereof till the depth of 50 μm, and the elongation value of which is 40% or higher while drawing it; manufacturing a cable 10 by making a conductor 12 by stranding a plurality of the copper alloy wires 11 and forming an insulating cover 13 on the periphery of the conductor 12; and ultrasonically joining a connection terminal 20 to the conductor 12 at the terminal of the cable 10.

Description

  The present invention relates to a method of joining a soft dilute copper alloy wire and a connection terminal for ultrasonically connecting a soft dilute copper alloy wire having high conductivity and having a high bending life even in a soft material to the connection terminal. is there.

  In recent science and technology, electricity is used in all parts such as electric power as a power source and electric signals, and wires such as cables and lead wires are used to transmit them. And as a material used for the conducting wire, a metal having high conductivity such as copper and silver is used, and in particular, a copper wire is very often used in consideration of cost.

  The copper and lump can be broadly divided into hard copper and soft copper according to the molecular arrangement. And the kind of copper which has a desired property according to the utilization purpose is used.

  Hard lead wires are often used as lead wires for electronic parts. For example, cables used in electronic devices such as medical devices, industrial robots, and notebook computers are combined with severe bending, twisting, and tension. Since it is used in an environment where external force is repeatedly applied, rigid hard copper wire is inaccurate and soft copper wire is used.

  Conductive wires used in such applications are required to have the opposite properties of good conductivity (high conductivity) and good bending properties. Development of a copper material that maintains its properties is underway (see Patent Document 1 and Patent Document 2).

  For example, the invention according to Patent Document 1 is an invention related to a conductor for a bending-resistant cable having good tensile strength, elongation, and electrical conductivity. Particularly, oxygen-free copper having a purity of 99.99 wt% or more is more than 99.99 wt% in purity. Bending Resistant Cable Conductor Formed with a Copper Alloy Containing 0.05 to 0.70 mass% of In and P of 0.009 to 0.003 Mass% Concentration in a Concentration Range of 0.0001 to 0.003 Mass% Have been described.

  The invention according to Patent Document 2 describes a bending-resistant copper alloy wire in which indium is 0.1 to 10 wt%, boron is 0.01 to 0.1 wt%, and the balance is copper.

  However, the invention according to Patent Document 1 is an invention related to a hard copper wire to the last, a specific evaluation regarding bending resistance has not been made, and a study on a soft copper wire with higher bending resistance has not been made. Absent. Moreover, since there is much quantity of an additional element, electroconductivity will fall. The soft copper wire has not been fully studied. Moreover, although the invention which concerns on patent document 2 is invention regarding a soft copper wire, since the addition amount of an additional element is large similarly to the invention which concerns on patent document 1, electroconductivity will fall.

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

  When this oxygen-free copper (OFC) is used as a raw material and it is used without adding other elements to maintain conductivity, the inside of the oxygen-free copper wire is increased by drawing the copper rough drawing wire to a higher degree of processing. Although it may be effective to improve the bending resistance by making the crystal structure fine, in this case, it is suitable for use as a hard wire by work hardening by wire drawing, but it is a soft wire. There is a problem that can not be applied to.

  On the other hand, an insulated wire or cable using a soft wire is excellent in flexibility, but generally has a risk of disconnection during use. For example, insulation coated copper wires used for multi-wire wiring boards have the following problems.

  That is, this multi-wire wiring board is manufactured by disposing an insulation-coated copper wire (oxygen-free copper wire) on an insulating substrate with an adhesive and welding it, but is manufactured by crossing a plurality of insulation-coated copper wires with each other. In general, quadruple cross wiring has been proposed. At the intersection where the existing wiring intersects, an extra length in the height direction is required, so the insulation-coated copper wire that is required in the height direction during the short time that the stylus passes through the intersection is fed with a feeder. There is a problem that the apparatus cannot cope with the supply, and the insulation-coated copper wire is stretched at the intersecting portion, and if it becomes excessive, the wire breaks.

  Therefore, the inventors of the present invention proposed a soft dilute copper alloy material containing 2 to 12 mass ppm of sulfur, 2 to 30 mass ppm of oxygen and 4 to 55 mass ppm of pure copper in Patent Document 3. This soft dilute copper alloy material has high productivity and can be excellent in electrical conductivity, softening temperature, and surface quality.

JP 2002-363668 A Japanese Patent Laid-Open No. 9-256084 JP 2010-265511 A JP 2011-192638 A

  However, the soft dilute copper alloy material of Patent Document 3 is for producing a wire rod by SCR continuous casting rolling or the like. When this wire rod is drawn into a soft dilute copper alloy wire, the soft dilute copper alloy material is used. There is no established technology for producing a soft dilute copper alloy wire while maintaining the electrical conductivity, softening temperature, and surface quality of the copper alloy material, and connecting this to the connection terminal by ultrasonic connection.

  Accordingly, an object of the present invention is to provide a high conductivity, have a high bending life even in a soft copper material, and can suppress disconnection during use as compared to an oxygen-free copper wire and a connection terminal. An object of the present invention is to provide a method for joining a soft dilute copper alloy wire capable of ultrasonic connection and a connection terminal.

  In order to achieve the above object, the present invention provides an additive element that easily binds to copper and S selected from the group consisting of Ti, Mg, Zr, Nb, Ca, V, Ni, Hf, Fe, Mn, and Cr. The soft dilute copper alloy material is annealed by drawing at a workability of 90% or more, the average grain size in the surface layer from the surface to a depth of 50 μm is 20 μm or less, and the elongation value after annealing is 40 % Of the rough drawn wire is annealed while being drawn to produce a soft dilute copper alloy wire, and a plurality of the soft dilute copper alloy wires are twisted to form a conductor, and an insulator is provided on the outer periphery of the conductor. A method for joining a soft dilute copper alloy wire and a connection terminal, comprising: a step of forming a cable by forming a coating; and a step of ultrasonically bonding a conductor at a terminal of the cable to the connection terminal. .

  In the step of producing the soft diluted copper alloy wire, the rough drawn wire is formed by rolling a soft diluted copper alloy material containing 2 to 12 mass ppm of sulfur, oxygen exceeding 2 to 30 mass ppm and Ti and 4 to 55 mass ppm of Ti. It is preferable to fabricate by annealing and annealing.

  The soft dilute copper alloy material is prepared by drawing a rough drawn wire at a molten copper temperature of 1200 to 1320 ° C. and a rolling temperature of 880 to 550 ° C., drawing the wire, and annealing at a annealing temperature of 150 to 550 ° C. It is preferable to use a soft dilute copper alloy wire having a final diameter by wire processing.

  According to the present invention, it has high conductivity, has a high bending life even in a soft copper material, has a high connection reliability even in a terminal connection portion, and is more in use than an oxygen-free copper wire. An excellent effect that the disconnection can be suppressed is exhibited.

It is a figure which shows the SEM image of TiS particle | grains. It is a figure which shows the analysis result of FIG. Is a view showing an SEM image of the TiO ₂ particles. It is a figure which shows the analysis result of FIG. In this invention, it is a figure which shows the SEM image of Ti-O-S particle | grains. It is a figure which shows the analysis result of FIG. It is a figure which shows the outline of a bending fatigue test. The bending life was measured in the comparative material 13 using an oxygen-free copper wire and the implementation material 7 using a soft dilute copper alloy wire obtained by adding Ti to low oxygen copper after annealing at 400 ° C. for 1 hour. It is a graph. The bending life was measured in the comparative material 14 using an oxygen-free copper wire after annealing at 600 ° C. for 1 hour and the working material 8 using a soft dilute copper alloy wire obtained by adding Ti to low oxygen copper. It is a graph. 2 shows a photograph of a cross-sectional structure in the width direction of the working material 8. It shows a photograph of the cross-sectional structure in the width direction of the sample of the comparative material 14. It is drawing for demonstrating the measuring method of the average grain size in the surface layer of a sample. 2 shows a photograph of a cross-sectional structure in the width direction of the working material 9. It shows a photograph of the cross-sectional structure in the width direction of the sample of the comparative material 15. It is a figure which shows the relationship between the annealing temperature of the implementation material 9 and the comparison material 15, and elongation (%). It is a cross-sectional photograph of the implementation material 9 at an annealing temperature of 500 ° C. It is a cross-sectional photograph of the implementation material 9 at an annealing temperature of 700 ° C. It is a cross-sectional photograph of the comparative material 15 in the annealing temperature of 700 degreeC. In this invention, it is a figure which shows the connection method of the copper alloy wire and connection terminal in a cable.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

First, the present invention has a conductivity of 98% IACS (conductivity with a universal annealed copper standard having a resistivity of 1.7241 × 10 ⁻⁸ Ωm as 100%), 100% IACS, and further 102% IACS. It is to obtain a soft dilute copper alloy material as a satisfactory soft steel. A secondary purpose is to use an SCR continuous casting and rolling facility, with few surface scratches, a wide manufacturing range, and stable production. Also, the development of a material with a semi-softening temperature of 148 ° C. or less at a processing degree of 90% (for example, φ8 mm → φ2.6 mm) for the wire rod.

  For high-purity copper (6N, purity 99.9999%), the semi-softening temperature at a processing degree of 90% is 130 ° C. Accordingly, it is possible to stably produce soft copper having a soft material having a conductivity of 98% IACS or more, 100% IACS or more, and further having a conductivity of 102% IACS or more at a semi-softening temperature of 130 ° C. or more and 148 ° C. or less capable of stable production. We investigated the raw materials and the manufacturing conditions for soft dilute copper alloy materials that can be manufactured.

  Here, high purity copper (4N) having an oxygen concentration of 1 to 2 mass ppm was used, and a small continuous casting machine (small continuous casting machine) was used in a laboratory, and the molten metal was manufactured from a molten metal with several mass ppm added to the molten metal. When the semi-softening temperature is measured with a φ8 mm wire rod of φ2.6 mm (working degree 90%), it is 160 to 168 ° C., and the semi-softening temperature is not lower than this. The conductivity is about 101.7% IACS. Therefore, it was found that even when Ti was added at a low oxygen concentration, the semi-softening temperature could not be lowered, and the electrical conductivity of high purity copper (6N) was worse than 102.8% IACS.

  The reason for this is that sulfur is contained in several mass ppm or more as an unavoidable impurity during the production of molten metal, and sulphide such as TiS is not sufficiently formed between this sulfur and titanium, so that the softening temperature is not lowered. .

  Therefore, in the present invention, in order to lower the semi-softening temperature and improve the electrical conductivity, two measures have been studied and the two effects have been combined to achieve the goal.

(A) Increase the oxygen concentration of the material to an amount exceeding 2 mass ppm and add titanium. Thereby, it is considered that TiS, titanium oxide (TiO ₂ ) and Ti—O—S particles are first formed in the molten copper (see the SEM images in FIGS. 1 and 3 and the analysis results in FIGS. 2 and 4). ). In FIGS. 2, 4, and 6, Pt and Pd are vapor deposition elements for observation.

(B) Next, by setting the hot rolling temperature lower (880 to 550 ° C.) than the normal copper production conditions (950 to 600 ° C.), dislocations are introduced into the copper and S is likely to precipitate. Like that. As a result, precipitation of S on the dislocations or precipitation of S using titanium oxide (TiO ₂ ) as a nucleus forms Ti—O—S particles and the like as an example of molten copper (SEM image of FIG. 5 and FIG. 6 shows the analysis result). 1 to 6 show SEM observation and EDX analysis of a cross section of a φ8 mm wire rod (rough drawing line) having oxygen concentration, sulfur concentration, and Ti concentration shown in the third row from the top in Example 1 of Table 1. It was evaluated. The observation conditions were an acceleration voltage of 15 KeV and an emission current of 10 μA.

  By (a) and (b), the sulfur in copper crystallizes and precipitates, and the wire rod which satisfies softening temperature and electrical conductivity after cold wire drawing is made.

  Next, in this invention, (1)-(3) was restrict | limited as a restriction | limiting of manufacturing conditions with SCR continuous casting rolling equipment.

(1) About composition The reason why the elements selected from the group consisting of Mg, Zr, Nb, Ca, V, Ni, Mn, Hf, Fe, Ti, and Cr were selected as the additional elements This is because it is an active element that is easily bonded to an element and can be easily bonded to S, so that S can be trapped and the copper base material (matrix) can be highly purified. One or more additive elements may be included. Also, other elements and impurities that do not adversely affect the properties of the alloy can be included in the alloy.

  Further, in the preferred embodiment described below, it is described that the oxygen content is more than 2 and not more than 30 mass ppm, but depending on the addition amount of the additive element and the S content, In the range having the property of, it is possible to include more than 2 and 400 mass ppm.

  When obtaining a soft copper material having an electrical conductivity of 98% IACS or higher, pure copper (base material) containing inevitable impurities is 3 to 12 mass ppm of sulfur, more than 2 and less than 30 mass ppm of oxygen, and 4 to Ti. A wire rod (rough drawing wire) is manufactured with a soft dilute copper alloy material containing 55 mass ppm. In this embodiment, so-called low oxygen copper (LOC) is targeted because it contains oxygen exceeding 2 mass ppm and not more than 30 mass ppm.

  Here, when obtaining a soft copper material having an electrical conductivity of 100% IACS or more, 2 to 12 mass ppm of sulfur, pure oxygen containing inevitable impurities, oxygen of 2 to 30 mass ppm and less and Ti to 4 to 37 mass. The wire rod is preferably made of a soft dilute copper alloy material containing ppm.

  Furthermore, when obtaining a soft copper material having an electrical conductivity of 102% IACS or more, pure copper containing inevitable impurities contains 3 to 12 mass ppm of sulfur, more than 2 and less than 30 mass ppm of oxygen, and Ti of 4 to 25 mass ppm. The wire rod is preferably made of a soft dilute copper alloy material.

  Usually, in the industrial production of pure copper, sulfur is taken into copper when producing electrolytic copper, so it is difficult to make sulfur 3 mass ppm or less. The upper limit of the sulfur concentration of general-purpose electrolytic copper is 12 mass ppm.

  As described above, if the amount of oxygen to be controlled is small, the semi-softening temperature is difficult to decrease, so the amount exceeds 2 mass ppm. Further, if there is too much oxygen, surface scratches are likely to occur in the hot rolling process, so it is set to 30 mass ppm or less.

(2) About dispersed substances It is desirable that the size of dispersed particles be small and distributed. The reason is that the size is small and the number is large because it functions as a sulfur deposition site.

Sulfur and titanium form compounds or aggregates in the form of TiO, TiO ₂ , TiS, and Ti—O—S, and the remaining Ti and S are present in the form of a solid solution. A soft dilute copper alloy material having a TiO size of 200 nm or less, TiO ₂ of 1000 nm or less, TiS of 200 nm or less, and Ti—O—S of 300 nm or less is distributed in the crystal grains. “Crystal grains” means the crystal structure of copper.

  However, since the size of the formed particles changes depending on the holding time of the molten copper during casting and the cooling condition, it is necessary to set casting conditions.

(3) About casting conditions By SCR speed reading casting rolling, a wire rod is manufactured with an ingot rod working degree of 90% (30 mm) to 99.8% (5 mm). As an example, φ8 mm at a working degree of 99.3% The method of making a wire rod (rough drawing wire) is used.

  (A) Molten copper temperature in a melting furnace shall be 1100 degreeC or more and 1320 degrees C or less. When the temperature of the molten copper is high, blowholes increase, scratches are generated, and the particle size tends to increase. The reason why the temperature is set to 1100 ° C. or higher is that copper is likely to solidify and the production is not stable, but the casting temperature is preferably as low as possible.

  (B) As for the hot rolling temperature, the temperature at the first rolling roll is 880 ° C. or lower, and the temperature at the final rolling roll is 550 ° C. or higher.

  Unlike normal pure copper production conditions, crystallization of sulfur in molten copper and precipitation of sulfur during hot rolling are the subject of the present invention, so in order to reduce the solid solubility limit that is the driving force. The molten copper temperature and the hot rolling temperature are preferably (a) and (b).

  The normal hot rolling temperature is such that the temperature at the first rolling roll is 950 ° C. or lower and the temperature at the final rolling roll is 600 ° C. or higher. In order to reduce the solid solution limit, The temperature at the first rolling roll is set to 880 ° C. or lower and the temperature at the final rolling roll is set to 550 ° C. or higher.

  (C) The electrical conductivity of a wire rod having a diameter of φ8 mm is 98% IACS or more, 100% IACS or more and 102% IACS or more, and the semi-softening temperature of the wire rod after cold drawing (for example, φ2.6 mm) is A soft dilute copper alloy wire having a temperature of 130 ° C. to 148 ° C. can be obtained.

  In order to use it industrially, it is necessary to use 98% IACS or more in the industrially used soft copper wire produced from electrolytic copper, and the semi-softening temperature is 148 ° C. or less in view of its industrial value. . When Ti is not added, the temperature is 160 to 165 ° C. Since the semi-softening temperature of high-purity copper (6N) was 127 to 130 ° C, the limit value is set to 130 ° C from the obtained data. This slight difference is in inevitable impurities not found in high purity copper (6N).

  The conductivity is about 101.7% IACS at the level of oxygen-free copper, and 102.8% IACS for high-purity copper (6N), so that the conductivity is as close as possible to high-purity copper (6N). Is desirable.

  After the base material copper was melted in the shaft furnace, it was controlled so as to be in a reduced state, that is, in a reducing gas (CO) atmosphere, the sulfur concentration, Ti concentration, and oxygen concentration of the constituent elements of the diluted alloy were controlled. A method of stably manufacturing a wire rod that is cast and rolled. Since the copper oxide is mixed and the particle size is large, the quality is lowered.

  Note that the additive element added to pure copper may include at least one of Mg, Zr, Nb, Ca, V, N, Hf, Fe, Mn, and Cr.

  Here, the reason for selecting Ti as the additive element is as follows.

  (A) Ti is easily bonded to sulfur in molten copper to form a compound.

  (B) It can be processed and handled more easily than other additive elements such as Zr.

  (C) It is less expensive than Nb or the like.

  (D) It is because it is easy to precipitate using an oxide as a nucleus.

  Thus, a soft dilute copper alloy material containing copper and an additive element selected from the group consisting of Ti, Mg, Zr, Nb, Ca, V, Ni, Hf, Fe, Mn and Cr, particularly 2 to 12 mass ppm. A soft dilute copper alloy material containing sulfur, oxygen greater than 2 and less than or equal to 30 mass ppm and Ti in an amount of 4 to 55 mass ppm is drawn at a molten copper temperature of 1200 to 1320 ° C and a hot rolling temperature of 880 to 550 ° C (φ8 mm). Wire rod), which is subjected to cold wire drawing using an in-line wire drawing machine or the like, and annealed at an annealing temperature of 150 to 550 ° C., so that the softening temperature is 130 ° C. to 148 ° C. and φ2.6 mm. A soft dilute copper alloy wire is used, and this is annealed with an in-line wire drawing machine to obtain a soft dilute copper alloy wire having a diameter of φ1 mm or less, and a plurality of soft dilute copper alloy wires are twisted together. And conductors Te, and the cable is subjected to insulation coating on the outer periphery thereof.

  The cable of the present invention has high electrical conductivity, can reduce energy during annealing, can be used as a soft copper wire, has high productivity, practical soft dilute copper alloy wire with excellent conductivity, semi-softening temperature and surface quality It is possible to obtain a cable consisting of

  FIG. 19 shows an example in which the cable 10 of the present invention is ultrasonically connected to the connection terminal 20.

  As shown in FIG. 19A, the cable 10 is formed by twisting a plurality of soft dilute copper alloy wires 11 made of the above soft dilute copper alloy wire to form a conductor 12, and an insulator coating 13 is provided on the outer periphery of the conductor 12. The connection terminal 20 is made of copper and is made of copper, and has a donut-shaped terminal portion 21 connected to a terminal of an electronic device, a U-shaped welded portion 22 connected to the conductor 12 of the cable 10, and a cable. 10 fixing covers 23 that are caulked and fixed to the insulator coating 13.

  For connection between the cable 10 and the connection terminal 20, the insulator coating 13 at the end of the cable 10 is peeled off to expose the conductor 12, and the conductor 12 is positioned at the welded portion 22 of the connection terminal 20. In this state, the lower surface of the connection terminal 20 is supported by an anvil (not shown) of an ultrasonic connection device, and a horn tip (not shown) is pressed against the conductor 12 in the welded portion 22 to apply ultrasonic vibration. As a result, the conductor 12 is deformed into a quadrangular cross section that matches the shape of the welded portion 22, and the conductor welded portion 12 w having the quadrangular cross section is welded to the welded portion 22. After that, as shown in FIG. 19B, the welding portion 22 and the fixing piece 23 are caulked to connect the connection terminal 20 to the cable 10.

  Further, a plating layer may be formed on the surface of the soft diluted copper alloy wire of the present invention. As the plating layer, for example, a layer mainly composed of tin, nickel, and silver is applicable, and so-called Pb-free plating may be used.

  Further, a plurality of soft diluted copper alloy wires of the present invention are twisted together to form a central conductor, an insulator coating is formed on the outer periphery of the central conductor, and an outer conductor made of copper or a copper alloy is disposed on the outer periphery of the insulator coating, It can also be used as a coaxial cable provided with a jacket layer on its outer periphery.

  Further, a plurality of coaxial cables can be arranged in the shield layer and used as a composite cable in which a sheath is provided on the outer periphery of the shield layer.

  In the above-described embodiment, the wire rod is manufactured by the SCR continuous casting rolling method, and the soft material is manufactured by hot rolling. However, the present invention is not limited to the twin roll continuous casting rolling method or the proper perch. You may make it manufacture by a type | formula continuous casting rolling method.

  Table 1 relates to experimental conditions and results.

  First, as an experimental material, a φ8 mm copper wire (wire rod) processing degree of 99.3% was prepared at the oxygen concentration, sulfur concentration, and Ti concentration shown in Table 1, respectively. The φ8 mm copper wire is hot-rolled by SCR continuous casting and rolling. Ti flows the molten copper melted in the shaft furnace into the reed in the reducing gas atmosphere, guides the molten copper flowing in the reed to the casting pot of the same reducing gas atmosphere, and after adding Ti in this casting pot, An ingot rod was produced with a mold formed between the cast ring and the endless belt through the nozzle. This ingot rod is hot-rolled to produce a φ8 mm copper wire. The experimental material was cold-drawn, the semi-softening temperature and conductivity at a size of φ2.6 mm were measured, and the dispersed particle size at a copper wire of φ8 mm was evaluated.

  The oxygen concentration was measured with an oxygen analyzer (Leco® oxygen analyzer). Each concentration of sulfur and Ti is the result of analysis with an ICP emission spectroscopic analyzer.

  The measurement of the semi-softening temperature in the size of φ2.6 mm was obtained from the result of quenching in water after holding each temperature at 400 ° C. or less for 1 hour and conducting a tensile test. It calculated | required using the result of the tensile test at room temperature, and the result of the tensile test of the soft copper wire which carried out the oil bath heat treatment for 1 hour at 400 degreeC. The temperature corresponding to the strength showing the value obtained by adding the tensile strengths of these two tensile tests and dividing by 2 was defined as the semi-softening temperature.

It is desirable that the dispersed particles have a small size and are distributed a lot. The reason is that the size is small and the number is large because it functions as a sulfur deposition site. That is, the case where the number of dispersed particles having a diameter of 500 nm or less was 90% or more was regarded as acceptable. Here, the “size” is the size of the compound and means the size of the major axis of the major axis and minor axis of the shape of the compound. The “particles” refer to the TiO, TiO ₂ , TiS, and Ti—O—S. “90%” indicates the ratio of the number of corresponding particles to the total number of particles.

  In Table 1, the comparative material 1 is a result of trial production of a copper wire having a diameter of φ8 mm in an Ar atmosphere in a laboratory, and is obtained by adding 0 to 18 mass ppm of Ti to a molten copper.

  With this addition of Ti, 13 mass ppm decreases to 160 ° C. and becomes minimum with a semi-softening temperature of 215 ° C. with zero Ti addition, and increases with the addition of 15.18 mass ppm, and the desired softening temperature is 148 ° C. or less. Did not become. However, although the industrially required conductivity was 98% IACS or more, it was satisfactory, but the overall evaluation was x.

  Therefore, a Ø8 mm copper wire (wire rod) was prototyped by adjusting the oxygen concentration to 7 to 8 mass ppm by the SCR continuous casting and rolling method.

  The comparative material 2 is one having a low Ti concentration (0.2 mass ppm) among the prototypes manufactured by the SCR continuous casting and rolling method, and the conductivity is 102% IACS or more, but the semi-softening temperature is 164 ° C, 157 ° C. Yes, because the required temperature of 148 ° C. or lower was not satisfied, the overall evaluation was x.

  About execution material 1, oxygen concentration and sulfur are almost constant (7-8 mass ppm, 5 mass ppm), and it is a result of a prototype material from which Ti concentration differs (4-55 mass ppm).

  When the Ti concentration is in the range of 4 to 55 mass ppm, the softening temperature is 148 ° C. or less, the conductivity is 98% IACS or more, 102% IACS or more, and the dispersed particle size is 500% or less of the particles of 90% or more. is there. And the surface of the wire rod is also clean, and all are satisfied as product performance (overall evaluation ○).

  Here, the case where the electrical conductivity satisfies 100% IACS or higher is when the Ti concentration is 4 to 37 mass ppm, and the case where the electrical conductivity satisfies 102% IACS or higher is when the Ti concentration is 4 to 25 mass ppm. When the Ti concentration was 13 mass ppm, the maximum conductivity was 102.4% IACS, and the conductivity was slightly lower in the vicinity of this concentration. This is because when Ti is 13 mass ppm, the sulfur content in copper is captured as a compound, thereby showing conductivity close to that of high-purity copper (6N).

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

  Comparative material 3 is a prototype material having a Ti concentration as high as 60 mass ppm. In this comparative material 3, the electrical conductivity satisfies the request, but the semi-softening temperature is 148 ° C. or higher, and the product performance is not satisfied. Furthermore, there were many surface damages on the wire rod, making it difficult to produce a product. Therefore, the addition amount of Ti is preferably less than 60 mass ppm.

  Next, Example Material 2 is a prototype material in which the sulfur concentration is set to 5 mass ppm, the Ti concentration is set to 13 to 10 mass ppm, and the oxygen concentration is changed to examine the influence of the oxygen concentration.

  Regarding the oxygen concentration, prototype materials with greatly different concentrations from 2 to 30 mass ppm or less were used. However, when oxygen is less than 2 mass ppm, production is difficult and stable production cannot be performed, so the overall evaluation is Δ. It was also found that even when the oxygen concentration was increased to 30 mass ppm, both the semi-softening temperature and the conductivity were satisfied.

  Moreover, as shown in the comparative material 4, when oxygen was 40 mass ppm, there were many scratches on the surface of the wire rod, and the product did not become a product.

  Therefore, by setting the oxygen concentration in the range of more than 2 and 30 mass ppm or less, the properties of semi-softening temperature, conductivity of 102% IACS or more, and dispersed particle size can be satisfied, and the surface of the wire rod is also clean. In any case, the product performance can be satisfied.

The inventors of the present invention understand that the added oxygen satisfies the above characteristics because it lowers the equilibrium solid solution amount of Ti with respect to copper. That is, it is understood that the reduction of the semi-softening temperature and the improvement of the electrical conductivity in the examples are caused by a decrease in the amount of Ti and S dissolved in copper. Oxygen itself has little influence on softening, but it reduces the solid solution amount of Ti and S in the working material. This decrease in the solid solution amount of Ti and S is considered to be caused by the formation of precipitation of compounds such as TiO, TiS, Ti—O—S, TiO ₂ , and in fact, as described above, TiO, TiS, Ti—O. Presence of compounds such as -S and TiO ₂ has been confirmed.

  Next, the implementation material 3 is an example of a prototype material in which the oxygen concentration and the Ti concentration are relatively close to each other, and the Ti concentration is changed to 4 to 20 mass ppm. In this material 3, the prototype material with less than 2 mass ppm of sulfur could not be realized from the raw material side, but by satisfying both the semi-softening temperature and the conductivity by controlling the concentrations of Ti and sulfur. Can do.

  When the sulfur concentration of the comparative material 5 was 18 mass ppm and the Ti concentration was 13 mass ppm, the semi-softening temperature was high at 162 ° C. and the required characteristics could not be satisfied. Moreover, since the surface quality of the wire rod was particularly poor, it was difficult to commercialize the product.

  From the above, when the sulfur concentration is 2 to 12 mass ppm, the characteristics of the semi-softening temperature, the conductivity of 102% IACS or more, and the dispersed particle size are all satisfied, and the surface of the wire rod is clean and all the product performance is achieved. I was satisfied.

  Moreover, although the examination result using high-purity copper (6N) as the comparative material 6 was shown, it is a semi-softening temperature 127-130 degreeC, electrical conductivity is 102.8% IACS, and dispersion particle size is also 500 nm or less. No particles were observed.

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

  Comparative material 7 shows the result of trial manufacture of a wire rod of φ8 mm at a molten metal temperature of 1330 to 1350 ° C. and a rolling temperature of 950 to 600 ° C.

  Although this comparative material 7 satisfied the semi-softening temperature and the electrical conductivity, the size of the dispersed particles was about 1000 nm, and the particles of 500 nm or more exceeded 10%. Therefore, this was inappropriate.

  The execution material 4 shows the result of trial manufacture of a φ8 mm wire rod at a molten copper temperature of 1200 to 1320 ° C. and a lower rolling temperature of 880 to 550 ° C. About this implementation material 4, the surface quality of the wire rod (WR) and the dispersed particle size were good, and the overall evaluation was good.

  Comparative material 8 shows the result of trial production of a wire rod of φ8 mm at a molten copper temperature of 1100 ° C. and a lower rolling temperature of 880 to 550 ° C. Since this comparative material 8 had a low molten copper temperature, the wire rod had many surface scratches and was not suitable for the product. This is because scratches are likely to occur during rolling because the molten copper temperature is low.

  Comparative material 9 shows the result of trial manufacture of a wire rod of φ8 mm at a molten metal temperature of 1300 ° C. and a higher rolling temperature of 950 to 600 ° C. Since this comparative material 9 had a high hot rolling temperature, the surface quality of the wire rod was good, but some of the dispersed particles were large, and the overall evaluation was x.

  Comparative material 10 shows the result of trial manufacture of a φ8 mm wire rod at a molten copper temperature of 1350 ° C. and a lower rolling temperature of 880 to 550 ° C. Since this comparative material 10 had a high molten copper temperature, some of the dispersed particles had a large size, and the overall evaluation was x.

[Soft characteristics of soft dilute copper alloy wire]
Table 3 shows a sample of the comparative material 11 using an oxygen-free copper wire and the embodiment material 5 using a soft dilute copper alloy wire containing 13 mass ppm Ti in low-oxygen copper, and annealing at different annealing temperatures for 1 hour. It is the table | surface which verified Vickers hardness (Hv) of what gave.

  The implementation material 5 was the same as the alloy composition described in the implementation material 1 of Table 1. As a sample, a 2.6 mm diameter sample was used. According to this table, when the annealing temperature is 400 ° C., the Vickers hardness (Hv) of the comparative material 11 and the execution material 5 is equivalent, and even when the annealing temperature is 600 ° C., the equivalent Vickers hardness (Hv) is shown. Yes. From this, the soft dilute copper alloy wire of the present invention has sufficient soft properties and has excellent soft properties even in the region where the annealing temperature exceeds 400 ° C., even when compared with the oxygen-free copper wire. I understand that.

[Study on yield strength and bending life of soft diluted copper alloy wire]
Table 4 shows a comparison material 12 using an oxygen-free copper wire and an embodiment material 6 using a soft dilute copper alloy wire containing 13 mass ppm Ti in low-oxygen copper, and annealed for 1 hour at different annealing temperatures. It is the table | surface which verified the transition of 0.2% proof stress value of what was given. As a sample, a 2.6 mm diameter sample was used.

  According to Table 4, the 0.2% proof stress value of the comparative material 12 and the execution material 6 is the same level when the annealing temperature is 400 ° C., and the execution material 6 and the comparative material 12 are substantially equivalent at the annealing temperature of 600 ° C. It turns out that it is 0.2% yield strength value.

  Next, the soft dilute copper alloy wire according to the present invention is required to have a high flex life, but the comparative material 13 using an oxygen-free copper wire and the soft dilute copper alloy wire obtained by adding Ti to low oxygen copper are used. The result of measuring the bending life of the used material 7 is shown in FIG.

  Here, as a sample, a 0.26 mm-diameter wire annealed at an annealing temperature of 400 ° C. for 1 hour is used, the comparative material 13 has the same component composition as the comparative material 11, and the implementation material 7 is also used. The component composition similar to that of Example Material 5 was used.

  Here, the bending life was measured by a bending fatigue test. The bending fatigue test is a test in which a load is applied and repeated bending strain of tension and compression is applied to the sample surface. The bending fatigue test is shown in FIG.

Specimen 2 is set between rings 3 and 3 of bending jig 1 as shown in (A), held by clamp 4, and the jig rotates 90 degrees as shown in (B) with load W applied. Give a bend. By this operation, a compressive strain is applied to the surface of the wire rod in contact with the bending jig, and a tensile strain is applied to the opposite surface correspondingly. Thereafter, the state returns to the state (A) again. Next, it is rotated 90 degrees in the direction opposite to the direction shown in FIG. Also in this case, a compressive strain is applied to the surface of the wire rod in contact with the bending jig, and a tensile strain is applied to the surface on the opposite side, corresponding to the state (C). And it returns to the first state (A) from (C). The time required for one cycle of bending fatigue (A) → (B) → (A) → (C) → (A) is 4 seconds. The surface bending strain can be obtained by the following equation.
Surface bending strain (%) = r / (R + r) × 100 (%)
R: strand bending radius (30 mm), r = element radius

  According to the experimental data of FIG. 8, the working material 7 according to the present invention showed a higher bending life than the comparative material 13.

  Moreover, the result of having measured the bending life in the comparative material 14 using an oxygen free copper wire and the implementation material 8 using the soft dilute copper alloy wire which added Ti to low oxygen copper is shown in FIG. Here, a sample obtained by subjecting a 0.26 mm diameter wire to an annealing temperature of 600 ° C. for 1 hour is used, the comparative material 14 has the same composition as the comparative material 11, and the implementation material 8 is also used. The component composition similar to that of Example Material 5 was used. The measuring method of the bending life was performed under the same conditions as the measuring method of FIG. Also in this case, the working material 8 according to the present invention showed a higher bending life than the comparative material 14. This result is understood to be due to the fact that the execution materials 7 and 8 showed a larger 0.2% proof stress value than the comparative materials 13 and 14 under any annealing conditions. Is done.

[Examination of crystal structure of soft dilute copper alloy wire]
10 shows a photograph of the cross-sectional structure in the width direction of the sample of the embodiment material 8, and FIG. 11 shows a photograph of the cross-sectional structure in the width direction of the comparative material 14. FIG. 11 shows the crystal structure of the comparative material 14, and FIG. 10 shows the crystal structure of the working material 8. From this, it can be seen that the crystal structure of the comparative material 14 has uniform crystal grains of uniform size as a whole from the surface to the center. On the other hand, the crystal structure of the embodiment material 8 has a sparse crystal grain size as a whole, and it should be noted that the crystal grain size in the thin layer formed near the surface in the cross-sectional direction of the sample is internal. It is extremely small compared to the crystal grain size.

  The inventors believe that the fine crystal grain layer that appears on the surface layer, which is not formed in the comparative material 14, contributes to the improvement of the bending characteristics of the working material 8.

  This is understood that, if the annealing treatment is normally performed at an annealing temperature of 600 ° C. for 1 hour, crystal grains uniformly coarsened by recrystallization are formed as in the comparative material 14. However, in the case of the present invention, the fine crystal grain layer still remains on the surface layer even when the annealing treatment is performed at an annealing temperature of 600 ° C. for 1 hour. It is considered that a soft dilute copper alloy material having a good thickness was obtained.

  And based on the cross-sectional photograph of the crystal structure shown to FIG. 10 and FIG. 11, the average crystal grain size in the surface layer of the sample of the implementation material 8 and the comparison material 14 was measured. Here, as shown in FIG. 12, the measurement method of the average crystal grain size in the surface layer is 1 mm in length from the surface of the cross section in the width direction of 0.26 mm diameter to the depth of 50 μm at 10 μm intervals in the depth direction. A value obtained by averaging the actually measured values of the crystal grain sizes in the range on the line was defined as the average crystal grain size in the surface layer.

  As a result of the measurement, the average crystal grain size in the surface layer of the comparative material 14 was 50 μm, whereas the average crystal grain size in the surface layer of the example material 8 was greatly different in that it was 10 μm. It is considered that the growth of cracks in the bending fatigue test was suppressed by the fine average grain size of the surface layer, and the bending fatigue life was extended (if the grain size is large, cracks propagate along the grain boundaries). If the crystal grain size is small, the direction of crack growth changes, so the growth is suppressed). As described above, this is considered to have caused a great difference in the bending characteristics between the comparative material and the working material.

  In addition, the average crystal grain size in the surface layer of the embodiment material 6 and the comparison material 12 having a diameter of 2.6 mm is 10 mm in length at a depth of 50 μm in the depth direction from the surface of the cross section in the width direction of 2.6 mm diameter. The grain size in the range was measured.

  As a result of the measurement, the average crystal grain size in the surface layer of the comparative material 12 was 100 μm, whereas the average crystal grain size in the surface layer of the example material 6 was 20 μm.

  As an effect of the present invention, the upper limit value of the average grain size of the surface layer is preferably 20 μm or less, and a value of 5 μm or more is assumed from the manufacturing limit value.

[Examination of crystal structure of soft dilute copper alloy material]
FIG. 13 shows a photograph of the cross-sectional structure in the width direction of the sample of the embodiment material 9, and FIG. 14 shows a photograph of the cross-sectional structure in the width direction of the comparative material 15. FIG. 13 shows the crystal structure of Example Material 9, and FIG.

  The implementation material 9 is a 0.26 mm diameter wire having the third highest soft material conductivity from the top of the implementation material 1 shown in Table 1. This execution material 9 is produced through an annealing treatment at an annealing temperature of 400 ° C. for 1 hour.

  The comparative material 15 is a 0.26 mm diameter wire made of oxygen-free copper (OFC). The comparative material 15 is manufactured through an annealing process at an annealing temperature of 400 ° C. for 1 hour. Table 5 shows the electrical conductivity of Example Material 9 and Comparative Material 15.

  As shown in FIG. 13 and FIG. 14, it can be seen that the crystal structure of the comparative material 15 has uniform crystal grains having the same overall size from the surface portion to the center portion. On the other hand, the crystal structure of the embodiment material 9 has a difference in crystal grain size between the surface layer and the inside, and the inside crystal grain size is extremely larger than the crystal grain size in the surface layer.

For example, the execution material 9 captures S in the copper of the conductor processed so as to have φ2.6 mm and φ0.26 mm in the form of Ti—S and Ti—O—S. The oxygen contained in the copper (O), for example, as TiO _2, is present in the form of TixOy, the crystal grains are precipitated in the grain boundaries.

  For this reason, when copper is annealed and the crystal structure is recrystallized, the recrystallized material 9 tends to proceed recrystallized, and the internal crystal grains grow greatly. For this reason, compared with the comparative material 15, the implementation material 9 progresses with less obstruction of the flow of electrons when a current is passed, and the electrical resistance is reduced. Therefore, the implementation material 9 has a higher conductivity (% IACS) than the comparison material 15.

  Based on the above results, the product using the embodiment material 9 is soft, has improved conductivity, and improved bending characteristics. In the conventional conductor, a high-temperature annealing process is required to recrystallize the crystal structure to the size of the embodiment material 9. However, if the annealing temperature is too high, S will be re-dissolved. Further, the conventional conductor has a problem that when it is recrystallized, it becomes soft and the bending property is lowered. In the embodiment material 9 described above, since it can be recrystallized without being twinned when annealed, the internal crystal grains become large and soft, but the surface layer is bent because fine crystals remain. There is a characteristic that the characteristics do not deteriorate.

[Relationship between elongation characteristics and crystal structure of soft dilute copper alloy wire]
FIG. 15 shows, as a sample, a comparative material 15 using an oxygen-free copper wire having a diameter of 2.6 mm and an embodiment material 9 using a soft dilute copper alloy wire containing 13 mass ppm of Ti in low-oxygen copper having a diameter of 2.6 mm. It is the graph which verified the transition of the value of elongation (%) of what annealed for 1 hour at different annealing temperature. The sample here is a wire drawn from an 8 mm diameter to a 2.6 mm diameter (working degree 90%). As the comparative material 15, the same composition as that described at the top of the comparative material 1 in Table 1 was used. A circle symbol shown in FIG. 15 indicates the implementation material 9, and a square symbol indicates the comparison material 15.

  According to this graph, it can be seen that the embodiment material 9 exhibits excellent elongation characteristics over a wide range from about 130 ° C. to 900 ° C., compared with the comparative material 15, with the annealing temperature exceeding 100 ° C. In particular, it can be seen that in the region where the annealing temperature is 150 ° C. to less than 600 ° C., excellent elongation characteristics are exhibited as compared with the comparative material 15. In particular, it can be seen that an elongation value of 40% or more is provided in the vicinity of an annealing temperature of 150 ° C to 550 ° C, and an elongation value of 45% or more is provided at an annealing temperature of 260 ° C to 400 ° C.

  Table 6 shows the elongation values after heat treatment for 1 hour for each temperature condition of the sample of the embodiment material 9 and the sample of the comparative example 15.

  In order to attempt a quantitative comparison between the elongation value of the sample of the embodiment material 9 and the elongation value of the sample of the comparative material 15, the average value of the elongation values in a state where the annealing treatment of the comparative material 15 was performed was obtained. This was compared with the elongation value of the sample of Example Material 9.

  In general, the annealed state of the soft copper wire means that the elongation value of the sample is about 25% or more, and here, the elongation value of 25% or more generally required as a soft copper wire is used. We decided to reference what we have.

  When the sample of the comparative material 15 was heat-treated for 1 hour under a temperature condition of 220 ° C. or lower, it was difficult to say that the annealing treatment was actually performed. Therefore, the elongation value in the heat treatment for 1 hour under the temperature condition of 150 ° C. was not measured. On the other hand, when the sample of the comparative material 15 was heat-treated at 500 ° C. for 1 hour, it showed an elongation value of 24% and was judged to be in an over-annealed state.

  For this reason, the average value of the elongation values of the samples of the comparative material 15 is the average value of the elongation values at four points at 240 ° C. to 400 ° C., which is judged to be in the state of being annealed as a soft copper wire ( 41.0%) was obtained, and the average value was used as a reference and compared with the elongation value of the sample of the embodiment material 9. Then, the average value of the elongation values of the samples of the comparative material 15 that is an oxygen-free copper wire for all the samples of the implementation material 9 that were subjected to the heat treatment for 1 hour under the temperature condition of 150 ° C. to 500 ° C. It was found that it showed an excellent elongation value of 1% or more higher than (41.0%).

  Further, FIG. 16 shows a cross-sectional photograph of the copper wire of the embodiment material 9 at an annealing temperature of 500 ° C. FIG. 16 shows that a fine crystal structure is formed in the entire cross section of the copper wire, and this fine crystal structure seems to contribute to the elongation characteristics. On the other hand, the cross-sectional structure of the comparative material 15 at the annealing temperature of 500 ° C. has undergone secondary recrystallization, and the crystal grains in the cross-sectional structure are coarser than the crystal structure of FIG. Is thought to have been reduced.

  Further, FIG. 17 shows a cross-sectional photograph of the copper wire of Example Material 9 at an annealing temperature of 700 ° C. It turns out that the crystal grain size of the surface layer in the cross section of a copper wire is very small compared with the crystal grain size inside. Although the internal crystal structure is undergoing secondary recrystallization, a fine crystal grain layer in the outer layer remains. Although the inner crystal structure grows greatly in the execution material 9, since the fine crystal layer remains on the surface layer, it seems that the elongation characteristics are maintained.

  On the other hand, in the cross-sectional structure of the comparative material 15 at the annealing temperature of 700 ° C. shown in FIG. 18, crystal grains having substantially the same size are arranged uniformly from the surface to the center, and secondary recrystallization is performed in the entire cross-sectional structure. Therefore, it is considered that the elongation property of the comparative material 15 in the high temperature region of 600 ° C. or higher is lower than that of the working material 9.

  As described above, the embodiment material 9 is superior to the comparison material 15 in terms of elongation characteristics, and therefore, it is excellent in handling property when producing a stranded wire using this conductor, excellent in bending resistance characteristics, and easy to bend. Also in this point, there is an advantage that the cable arrangement becomes easy.

  In addition, the embodiment material 9 has an average crystal grain size of 20 μm or less in the surface layer at least from the surface to a depth of 50 μm, and is 1% or more higher than the average value of the elongation of the oxygen-free copper wire subjected to the annealing treatment. Since it has an excellent elongation value, if it is used for, for example, an insulating coated copper wire of a multi-wire wiring board, a plurality of insulating coated copper wires having an insulating layer formed on the surface of the copper wire on an insulating substrate with an adhesive Even if it is used by forming a crossed portion crossing each other and welding, compared with the case of using a conventional oxygen-free copper wire, it can reduce the risk of disconnection in the middle of wiring work, There is an advantage that the reliability of the wiring can be increased.

  Next, the implementation material 9 and the comparative material 15 are drawn and energized with an in-line wire drawing machine from an 8 mm diameter, for example, to produce a 2.6 mm diameter annealed wire. The obtained 2.6 mm diameter wire is drawn and energized with an in-line wire drawing machine to produce a 0.45 mm diameter soft copper wire. Table 7 shows a comparison of applied energy when 50 twisted soft copper wires having a diameter of 0.45 mm are connected to a copper terminal by ultrasonic connection.

  According to this, it can be seen that the working material 9 can be connected with less energy than the comparative material 15. This is presumably because the conductor 9 is easy to deform due to the softness of the embodiment material 9.

  In addition, the conductor after connection may reduce cracks that develop in the conductor due to less damage during connection and fine surface crystals, even when vibration and cooling cycles during actual use are loaded. It becomes possible. As a result, credibility can be improved.

  As mentioned above, although embodiment of this invention and its modification were demonstrated, embodiment and modification which were described above do not limit the invention which concerns on a claim. In addition, it should be noted that not all combinations of features described in the embodiments and the modifications are necessarily essential to the means for solving the problems of the invention.

10 Cable 11 Soft dilute copper alloy wire 12 Conductor 13 Insulator coating 20 Connection terminal 22 Welded part

Claims (3)

A soft dilute copper alloy material containing copper and an additive element that easily binds to S selected from the group consisting of Ti, Mg, Zr, Nb, Ca, V, Ni, Hf, Fe, Mn, and Cr. The wire was drawn and annealed, and a rough drawn wire having an average grain size of 20 μm or less in the surface layer from the surface to a depth of 50 μm and an elongation value after annealing of 40% or more was drawn. While performing annealing while producing a soft dilute copper alloy wire,
Twisting a plurality of the soft dilute copper alloy wires into a conductor, and forming a cable by forming an insulator coating on the outer periphery of the conductor; and
And a step of ultrasonically bonding a conductor at a terminal of the cable to a connection terminal. A method for bonding a soft dilute copper alloy wire and a connection terminal.   In the step of producing the soft diluted copper alloy wire, the rough drawn wire is cast and rolled of soft diluted copper alloy material containing 2 to 12 mass ppm of sulfur, oxygen of more than 2 and less than or equal to 30 mass ppm and Ti of 4 to 55 mass ppm. The joining method of the soft dilute copper alloy wire and the connection terminal according to claim 1 manufactured by annealing and annealing.   The soft dilute copper alloy material is prepared by drawing a rough drawn wire at a molten copper temperature of 1200 to 1320 ° C. and a rolling temperature of 880 to 550 ° C., drawing the wire, and annealing at a annealing temperature of 150 to 550 ° C. The joining method of the soft dilute copper alloy wire and the connection terminal according to claim 2, wherein the wire dilute is used as a soft dilute copper alloy wire having a final diameter.