JP2013040384A - Wiring material and plate material using soft dilute copper alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring material and plate material using soft dilute copper alloy that has high conductivity, and also a superior bending property even in soft copper material.SOLUTION: The wiring material is formed of a soft dilute copper alloy containing an additive element selected from a group containing Ti, Mg, Zr, Nb, Ca, V, Ni, Mn, and Cr, and the balance of copper, and has a bend portion. The wiring material employs a soft dilute copper alloy characterized in that the crystal structure of the wiring material has an average crystal grain size of 20 μm or less in the surface layer ranging from at least the surface to the depth of 50 μm.

Description

  The present invention relates to a wiring material and a plate material using a soft dilute copper alloy having high conductivity and having excellent bendability even in a soft material.

  With the development of science and technology in recent years, equipment using electricity as an energy source and signal source has been increasing. And in those equipment, lead wires are used. As a material used for the conducting wire, a metal having high conductivity such as copper or silver is used, and in particular, a copper wire is very often used in consideration of cost.

  The types of copper are roughly classified into hard copper and soft copper according to the arrangement of the molecules. And the kind of copper which has a desired property according to the utilization purpose is used.

  Electronic devices have been developed to be more multifunctional, faster, and smaller, and the wiring material housed inside the device is also required to be reduced in size by reducing the diameter.

  In addition to downsizing by reducing the diameter of the wiring material, a smaller radius of curvature and bending resistance are required in order to handle a narrower space. As bending resistance, a soft conductor or a conductor that does not break even when bent is required.

  On the other hand, when the diameter is reduced, the resistance of the conductor increases, and thus a problem appears in the form of energy loss and signal loss. Therefore, the wiring material is required to have high conductivity.

  Moreover, as a conductor for conveying electricity as energy, for example, a rectangular conductor for a solar cell can be mentioned. In a solar cell, a rectangular conductor (bus bar) is used to extract electricity generated from a battery cell and a module obtained by combining them. The bus bar material is naturally required to have high conductivity as a conductor, but a soft conductor is also required to prevent cell destruction due to a difference in thermal expansion from silicon used as a cell material. Furthermore, in order to maximize the light receiving area, bending resistance is required as a wiring property (see Patent Document 1 and Patent Document 2).

  For example, Patent Document 1 proposes a flex-resistant cable conductor having good tensile strength, elongation and electrical conductivity. In particular, oxygen-free copper having a purity of 99.99 wt% or more is added with indium having a purity of 99.99 wt% or more. It describes a conductor for a bending-resistant cable in which a copper alloy containing 0.05 to 0.70 mass% and phosphorus having a purity of 99.9 wt% or more in a concentration range of 0.0001 to 0.003 mass% is formed on a wire. Yes.

  Patent Document 2 describes a bending-resistant copper alloy wire in which indium is 0.1 to 1.0 wt%, boron is 0.01 to 0.1 wt%, and the balance is copper.

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

  However, Patent Document 1 is only related to a hard conductive wire, a specific evaluation regarding bending resistance has not been made, and no study has been made on a soft copper wire having excellent bending resistance. Moreover, since there is much quantity of an additional element, electroconductivity will fall. Therefore, it cannot be said that the soft copper wire has been sufficiently studied. Moreover, although patent document 2 is related with a soft copper wire, since the addition amount of an additional element is large like patent document 1, electroconductivity will fall.

  On the other hand, it is conceivable to ensure 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 OFC is used as a raw material and it is used without adding other elements to maintain conductivity, the fine structure of the OFC wire is refined by increasing the degree of processing of the copper rough drawing wire and drawing. However, in this case, it is suitable for use as a hard copper material by work hardening by wire drawing, but it cannot be applied to a soft copper material. is there.

  Generally, when a metal is bent, a tensile stress is applied to the outside of the bent portion, and a compressive stress is applied to the inside. Such stress increases as the bending angle increases and as the wire diameter and plate thickness increase. It is known that when a metal is plastically deformed, a defect enters a lattice that constitutes the metal, and its density increases, thereby making it difficult to deform. When stress is applied by bending, deformation is unlikely to occur, that is, hardening due to processing occurs, and fracture occurs when it cannot withstand the deformation.

  Therefore, in order to raise bending resistance, it must be a soft copper material.

  Also, fine particles are better to make it easier to move lattice defects, but in the case of soft copper material, the process of enlarging the particles of annealing and recrystallization, so the particles can not be made fine, There is a problem that the bending resistance cannot be increased.

  The present inventors disclosed in Patent Document 3 a dilute product with high conductivity that can be manufactured by a continuous casting and rolling method, etc., and that has higher conductivity than pure copper level while maintaining conductivity and elongation characteristics at pure copper level. A copper alloy material was proposed.

  However, this Patent Document 3 does not consider the bendability when a dilute copper alloy material is used as a wiring material or a plate material.

  Accordingly, an object of the present invention is to provide a wiring material and a plate material using a soft dilute copper alloy having high conductivity and having excellent bendability even in a soft copper material.

  To achieve the above object, the present invention provides a soft dilute copper alloy containing an additive element selected from the group consisting of Ti, Mg, Zr, Nb, Ca, V, Ni, Mn, and Cr, with the balance being copper. A wiring material having a bent portion, and using a soft dilute copper alloy having an average crystal grain size of 20 μm or less in the surface layer of the wiring material having a crystal structure at least from the surface to a depth of 50 μm. .

  Further, the present invention includes an additive element selected from the group consisting of Ti, Mg, Zr, Nb, Ca, V, Ni, Mn, and Cr, and the balance is made of a soft dilute copper alloy made of copper, and the bent portion is made A soft dilute copper alloy having a surface layer in which an average crystal grain size of the wiring material having a surface structure of at least 20% of the wire diameter from the surface to the inside is 15 μm or less is used. Wiring material.

  The crystal structure of the wiring material is preferably a recrystallized structure having a grain size distribution in which the crystal grain size is large inside and the crystal grain size is small in the surface layer.

  The soft dilute copper alloy wire preferably contains 2 to 12 mass ppm of sulfur, 2 to 30 mass ppm of oxygen, and 4 to 55 mass ppm of Ti.

  Further, the present invention includes an additive element selected from the group consisting of Ti, Mg, Zr, Nb, Ca, V, Ni, Mn, and Cr, and the balance is made of a soft dilute copper alloy made of copper, and the bent portion is made A plate material using a soft dilute copper alloy having an average crystal grain size of 20 μm or less in a surface layer where the crystal structure of the plate material is at least from the surface to a depth of 50 μm.

  Furthermore, the present invention includes an additive element selected from the group consisting of Ti, Mg, Zr, Nb, Ca, V, Ni, Mn, and Cr, and the remainder is made of a soft dilute copper alloy made of copper, and the bent portion is formed. A plate material using a soft dilute copper alloy having a surface layer having an average crystal grain size of 15 μm or less from a surface of the plate material to a depth of 20% of the plate thickness from the surface to the inside. is there.

  The crystal structure of the plate material is preferably a recrystallized structure having a particle size distribution in which the crystal grain size is large inside and the crystal grain size is small in the surface layer.

  The soft dilute copper alloy preferably contains 2 to 12 mass ppm of sulfur, 2 to 30 mass ppm of oxygen, and 4 to 55 mass ppm of Ti.

  According to the present invention, a wiring material using a soft dilute copper alloy having a higher conductivity than a conventional OFC material and a tough pitch copper (TPC) material and having an excellent bendability compared to a conventional OFC material, and The excellent effect of providing a plate material is exhibited.

It is a figure which shows the cross-sectional structure | tissue of the width direction of the implementation material D in this invention. It is a figure which shows the cross-sectional structure | tissue of the width direction of the comparative material D. FIG. In this invention, it is a schematic diagram of the measuring method of the average crystal grain size in a surface layer. It is a figure which shows the cross-sectional structure | tissue of the width direction of the implementation material E in this invention. 5 is a view showing a cross-sectional structure in the width direction of a comparative material E. FIG. It is a figure which shows the cross-sectional structure of the copper wire of the implementation material E1 in this invention. It is a figure which shows the cross-sectional structure | tissue of the copper wire of the implementation material E2 in this invention. It is a figure which shows the cross-sectional structure of the copper wire of the comparative material E. In this invention, it is a figure which shows the outline | summary of a bending fatigue test. It is a figure which shows the bending characteristic of the implementation material B and the comparison material B of this invention. It is a figure which shows the bending characteristic of the implementation material C and comparative example C of this invention. In this invention, it is a figure which shows the bus-bar which bent the wiring direction at right angle by folding at 45 degrees in a plane direction. In this invention, it is a figure which shows the bus-bar which gave 180 degree | times bending to the perpendicular direction. In this invention, it is a figure which shows the bus-bar which gave 90 degrees bending in the horizontal direction. It is a figure which shows the cross-sectional structure | tissue of the width direction of the implementation material F in this invention. 5 is a view showing a cross-sectional structure in the width direction of a comparative material F. FIG. 5 is a schematic diagram of a method for measuring an average crystal grain size in the surface layer of an implementation material F and a comparative material F.

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

  The present invention includes an additive element selected from the group consisting of Ti, Mg, Zr, Nb, Ca, V, Ni, Mn, and Cr, and a wiring having a bent portion made of a soft dilute copper alloy with the balance made of copper. A wiring material using a soft dilute copper alloy having an average crystal grain size of 20 μm or less in a surface layer where the crystal structure of the wiring material is at least from the surface to a depth of 50 μm of the wire diameter.

  Further, the present invention includes an additive element selected from the group consisting of Ti, Mg, Zr, Nb, Ca, V, Ni, Mn, and Cr, and the balance is made of a soft dilute copper alloy made of copper, and the bent portion is made A soft dilute copper alloy having a surface layer in which an average crystal grain size of the wiring material having a surface structure of at least 20% of the wire diameter from the surface to the inside is 15 μm or less is used. Wiring material.

  First, the structure of the conductor used for the wiring material and board | plate material using the diluted copper alloy of this invention is demonstrated.

(1) About additive element The conductor used for the wiring material and board | plate material of this invention contains the additive element selected from the group which consists of Ti, Mg, Zr, Nb, Ca, V, Ni, Mn, and Cr, and the remainder Is a soft dilute copper alloy material that is copper and inevitable impurities.

  The reason for selecting an element selected from the group consisting of Ti, Mg, Zr, Nb, Ca, V, Ni, Mn, and Cr as an additive element is that these elements are easily active elements that are easily combined with other elements. This is because S can be trapped because it is easily combined with S, and the copper base material (matrix) can be highly purified and the hardness of the material can be reduced. 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 explained that the oxygen content is better than 2 mass ppm and 30 mass ppm or less, but depending on the addition amount of the additive element and the S content, In the range provided with the property of an alloy, it can contain more than 2 mass ppm and 400 mass ppm.

(2) About the composition ratio The conductor as the wiring material and the plate material is, for example, a conductivity of 98% IACS (International Annealed Copper Standard) or more and a resistivity of 1.7241 × 10 ⁻⁸ Ωm is 100% It is preferable to use a soft dilute copper alloy material as a soft copper material that satisfies 100% IACS or more, more preferably 102% IACS or more.

  When obtaining a soft copper material having an electrical conductivity of 98% IACS or more, as pure copper (base material) containing inevitable impurities, 3 to 12 mass ppm of sulfur, 2 mass ppm to more than 30 mass ppm of oxygen, and 4 to 55 mass ppm A soft dilute copper alloy material containing titanium is used, and a wire rod (rough drawing wire) is manufactured from the soft dilute copper alloy material.

  Here, when obtaining a soft copper material having an electrical conductivity of 100% IACS or higher, as pure copper (base material) containing inevitable impurities, 2 to 12 mass ppm of sulfur, 2 mass ppm to oxygen and 30 mass ppm or less of oxygen A soft dilute copper alloy material containing 4-37 mass ppm titanium is used.

  Further, when obtaining a soft copper material having an electrical conductivity of 102% IACS or more, as pure copper (base material) containing inevitable impurities, 3 to 12 mass ppm of sulfur, more than 2 mass ppm and oxygen of 30 mass ppm or less, A soft dilute copper alloy material containing 4 to 25 mass ppm of titanium is used.

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

  When the oxygen concentration is low, the hardness of the conductor used for the wiring material and the plate material is unlikely to decrease, so the oxygen concentration is controlled to an amount exceeding 2 mass ppm. Further, when the oxygen concentration is high, the surface of the conductor is likely to be damaged in the hot rolling process, so it is controlled to 30 mass ppm or less.

(3) Crystal structure of wiring material and plate material The wiring material and the plate material according to the present invention have 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.

  If the average grain size of the surface layer is large, cracks will propagate along the grain boundaries, but if the grain size is small, the direction of crack growth will change from grain boundary to grain boundary. It is considered that the bending fatigue life can be suppressed and the resistance to a large bending strain, that is, the bending resistance can be improved.

  Moreover, it is because an improvement in elongation can be expected due to the presence of fine crystals in the surface layer. The reason for this is that the local strain introduced near the grain boundary due to tensile deformation becomes smaller as the crystal grain size becomes finer, which contributes to the relaxation of the grain boundary stress concentration. This is because it is considered that the grain boundary destruction is suppressed.

  Further, in the present invention, the average crystal grain size in the surface layer at least from the surface to a depth of 50 μm is 20 μm or less is not limited to a configuration in which a fine crystal layer exists only at a depth of 50 μm in wire diameter. However, as long as the effects of the present invention are provided, it is not excluded that the fine crystal layer exists in the center of the wire in the depth direction of the wire diameter.

  The average crystal grain size corresponds to those having a diameter of 100 μm or more, but those having a diameter of 100 μm or less are not suitable because the surface layer up to a depth of 50 μm of the wire diameter exceeds the center of the wire. It is. Therefore, for an object having a diameter of less than 100 μm, the measurement location is defined by the ratio of the wire diameter in the depth direction, and the average grain size in the surface layer from the surface to a depth of 20% of the wire diameter is 15 μm or less. Targeted.

(4) About dispersed substances It is preferable that the size of dispersed particles dispersed in the wiring material and board according to the present invention is small, and that many dispersed particles are dispersed in the wiring material and board. Is preferred. The reason for this is that the dispersed particles have a function as a sulfur precipitation site, and the precipitation sites are required to have a small size and a large number. As a result, the formation of the dispersed particles and the deposition of sulfur on the dispersed particles are required. This is because the purity of the matrix of the copper base material is improved and the material hardness is reduced.

Specifically, the sulfur and titanium contained in the wiring material and the plate material are TiO, TiO ₂ , TiS, a compound having a Ti—O—S bond, or a TiO, TiO ₂ , TiS, or Ti—O—S bond. The remaining Ti and S are included as a solid solution.

(Wiring material manufacturing method according to the present embodiment)
The method for manufacturing the wiring material according to the present embodiment is as follows. As an example, a case where Ti is selected as an additive element will be described.

  First, a soft dilute copper alloy material containing Ti as a raw material for a wiring material is prepared (raw material preparation step).

  Next, this soft dilute copper alloy material is made into a molten metal at a molten copper temperature of 1100 ° C. or higher and 1320 ° C. or lower (melt manufacturing process).

  A wire rod is produced from this molten metal (wire rod production process).

  Subsequently, the wire rod is hot-rolled at a temperature of 880 ° C. or lower and 550 ° C. or higher (hot rolling step).

  Further, the wire rod that has undergone the hot rolling process is subjected to wire drawing and heat treatment (wire drawing, heat treatment step).

  As a heat treatment method, traveling annealing using a tubular furnace, electric annealing using resistance heat generation, or the like can be applied. In addition, batch-type annealing is also possible.

  As described above, the wiring material and the plate material according to the present embodiment are manufactured.

  In addition, for the production of the wiring material and plate material, a soft dilute copper alloy containing the above-mentioned sulfur of 2 mass ppm to 12 mass ppm, oxygen of more than 2 mass ppm to 30 mass ppm and titanium of 4 mass ppm to 55 mass ppm. It is preferable to use materials.

  The conductor used for the wiring material according to the present embodiment uses SCR continuous casting equipment, has few scratches on the surface, has a wide manufacturing range, and can be stably produced.

  By SCR continuous casting and rolling, a wire rod is manufactured with an ingot rod working degree of 90% (30 mm) to 99.8% (5 mm). As an example, a condition for manufacturing a wire rod of φ8 mm with a processing degree of 99.3% is adopted.

  The molten copper temperature in the melting furnace is preferably controlled to 1100 ° C. or higher and 1320 ° C. or lower. When the temperature of the molten copper is high, blowholes increase, and scratches are generated and the particle size tends to increase, so the temperature is controlled to 1320 ° C. or lower. Moreover, although the reason for controlling to 1100 degreeC or more is because copper is hardened easily and manufacture is not stable, molten copper temperature is desirable as low as possible.

  As for the temperature of the hot rolling process, it is preferable to control the temperature in the first rolling roll to 880 ° C. or lower and the temperature in the final rolling roll to 550 ° C. or higher.

  These casting conditions are different from ordinary pure copper production conditions, and aim to reduce the solid solubility limit, which is the driving force for crystallization of sulfur in molten copper and precipitation of sulfur during hot rolling. Is.

  Further, the temperature in the normal hot rolling process is 950 ° C. or less in the first rolling roll and 600 ° C. or more in the final rolling roll, but for the purpose of reducing the solid solution limit, It is desirable to set 880 ° C. or lower for the first rolling roll and 550 ° C. or higher for the final rolling roll.

  The reason why the temperature in the final rolling roll is set to 550 ° C. or higher is that when the temperature is lower than 550 ° C., the obtained wire rod has many scratches and the manufactured conductor cannot be handled as a product. The temperature in the hot rolling process is preferably as low as possible while controlling the temperature to 880 ° C. or lower in the first rolling roll and 550 ° C. or higher in the final rolling roll. By setting such a temperature, the hardness of the conductor matrix can be made close to that of high-purity copper (5N or more).

  After the base material copper is melted in the shaft furnace, it is preferably flowed into the trough in a reduced state. That is, in a reducing gas (for example, CO) atmosphere, the wire rod is stably manufactured by casting while controlling the sulfur concentration, titanium concentration, and oxygen concentration of the dilute alloy and rolling the material. It is preferable. In addition, mixing of copper oxide and / or a particle size larger than a predetermined size degrades the quality of the manufactured conductor.

  As described above, a soft dilute copper alloy material that is softer than the conductor of oxygen-free copper (OFC) or tough pitch copper (TPC) can be obtained as a raw material for the wiring material and the plate material according to the present embodiment.

  Next, the wire rod subjected to the hot rolling process is subjected to wire drawing to obtain a wiring material and a plate material. By performing heat treatment, the average crystal grain size in the surface layer from the surface to a depth of 50 μm can be made to be a crystal structure of 20 μm or less, thereby making it possible to make the wiring material and plate material have excellent bendability. It becomes.

  A plating layer can also be formed on the surfaces of the wiring material and the plate material. Furthermore, the shapes of the wiring material and the plate material are not particularly limited, and can be a round cross-section, a rod shape, or a flat conductor shape.

  In the present embodiment, the wire rod is manufactured by the SCR continuous casting and rolling method, and the soft material is manufactured by hot rolling, but the twin roll type continuous casting rolling method or the Properti type continuous casting and rolling method is adopted. You can also.

(Soft dilute copper alloy material)
First, as an experimental material 1, a φ8 mm copper wire (wire rod, workability 99.3%) having an oxygen concentration of 7 mass ppm to 8 mass ppm, a sulfur concentration of 5 mass ppm, and a titanium concentration of 13 mass ppm was prepared. 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.

  Next, each wire 1 was cold drawn. Thus, a copper wire having a size of φ2.6 mm was produced.

  First, using the copper wire of φ2.6 mm size, the characteristics of the conductor according to the embodiment of the present invention were verified.

(Examination of soft and bending resistance of soft dilute copper alloy wire)
Table 1 shows samples of Comparative Material A using oxygen-free copper wire and Example Material A using soft dilute copper alloy wire containing 13 mass ppm Ti in low-oxygen copper, at different annealing temperatures for 1 hour. It is the result of having verified the Vickers hardness (Hv) of what annealed.

  As the execution material A, the same alloy composition as described in the experimental material 1 was used. As a sample, a φ2.6 mm sample was used. According to this table, when the annealing temperature is 400 ° C., the Vickers hardness (Hv) of the comparative material A and the execution material A becomes the same level, 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.

  Next, since the wiring material and the plate material using the soft diluted copper alloy according to the present invention are required to be excellent in bending, the bending resistance was evaluated from the bending life by the 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 performed using a bending head 1 as shown in FIG. The sample 2 is set between the bending jigs 3 (rings) as shown in (A), held by the clamp 4, and the bending head 1 rotates 90 degrees as shown in (B) while the load W is 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 3, 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 3, 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), and (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

  Bending resistance is a value when the surface bending strain is bent by its own diameter, that is, when the wire bending radius in the previous equation is equal to the wire radius, and is examined from the number of bendings when the surface bending strain is 50% or more. It is possible. Therefore, the test results to be described later can be extrapolated upward and obtained from the value when the surface bending strain is 50%.

  FIG. 10 shows the results of subjecting a 0.26 mm diameter wire to an annealing temperature of 400 ° C. for 1 hour. As the sample, a comparative material B using an oxygen-free copper wire, and an implementation material B having the same component composition as the experimental material 1 were used.

  As a result, the working material B according to the present invention showed a higher bending life than the comparative material B.

  In addition, FIG. 11 shows the result of subjecting a 0.26 mm diameter wire to annealing at 600 ° C. for 1 hour. As a sample, a comparative material C using an oxygen-free copper wire, and an implementation material C having the same composition as that of the experimental material 1 were used. Also in this case, the working material C according to the present invention showed a higher bending life than the comparative material C.

  From this result, when the same bending strain was applied, the working materials B and C had a larger number of bendings than the comparative materials B and C, and therefore the bending resistance of the working materials B and C according to the present invention was also increased. It is clear that this is better.

[Examination of crystal structure and bending resistance of soft dilute copper alloy material]
The experimental material 1 is annealed at an annealing temperature of 600 ° C. for 1 hour to obtain an implementation material D, and the oxygen-free copper wire is annealed at an annealing temperature of 600 ° C. for 1 hour to obtain a comparative material D. The tissue was observed under a microscope.

  FIG. 1 shows a crystal structure of the embodiment material D showing a photograph of the cross-sectional structure in the width direction of the sample of the embodiment material D, and FIG. The crystal structure of the material D is shown.

  From this, it can be seen that the crystal structure of the comparative material D 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 D has a sparse crystal grain size as a whole, and it should be noted that the crystal grain size in the layer formed thin 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 consider that the fine crystal grain layer appearing on the surface layer, which is not formed in the comparative material D, is a factor in improving the elongation characteristics and bending resistance of the working material D.

  It is understood that normally, when annealing is performed at an annealing temperature of 600 ° C. for 1 hour, crystal grains uniformly coarsened by recrystallization are formed like the comparative material D. However, in the case of the present invention, even if an annealing process is performed at an annealing temperature of 600 ° C. for 1 hour, a fine crystal grain layer remains on the surface layer. Therefore, when bending is performed, it is conceivable that the progress of cracks is suppressed by the fine crystals of the surface layer, and as a result, it is assumed that the bending can be performed without leading to the entire fracture. Moreover, since it is a soft copper material, since it is excellent also in the tolerance with respect to the elongation of a crystal | crystallization, it is thought that the soft dilute copper alloy material with favorable bendability was obtained.

  And based on the cross-sectional photograph of the crystal structure shown to FIG. 1 and FIG. 2, the average crystal grain size in the surface layer of the sample of the implementation material D and the comparison material D was measured.

  Here, as shown in FIG. 3, the average grain size measurement method 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 Comparative Material D was 50 μm, whereas the average crystal grain size in the surface layer of Example Material D was greatly different in that it was 10 μm. If the average grain size of the surface layer is large, cracks will propagate along the grain boundaries, but if the grain size is small, the direction of crack growth will change from grain boundary to grain boundary. It is considered that the bending fatigue life was prolonged. As a result, it is considered that the resistance to a large bending strain, that is, the bending resistance is improved by reducing the average crystal grain size of the surface layer.

  Moreover, the average crystal grain size in the surface layer of the embodiment material B having a diameter of 2.6 mm and the comparative material B 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 B was 100 μm, whereas the average crystal grain size in the surface layer of the example material B 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.

  From the above, by using the soft dilute copper alloy according to the present invention, for example, when wiring in a narrow place, it is possible to bend at a narrower angle and lay with a small bending radius than conventional materials. is there.

  For example, as shown in FIG. 12, it is possible to accurately produce a structure such as a bus bar 10 that can be wired at a right angle by bending it to 45 ° with respect to the plane direction of the plate.

  Moreover, even in the case of the bus bar 10 bent 180 ° in the vertical direction as shown in FIG. 13 and the bus bar 10 bent 90 ° in the horizontal direction as shown in FIG. It becomes possible.

  As a result, it is not necessary to use bus bars with soldered conductors at the corners as in the past, and wiring materials such as bus bars and tab wires are not subject to bending or repeated bending stress and damage when laying. The resulting adverse electrical effects can be mitigated.

  4 shows a crystal structure of the embodiment material E showing a photograph of the cross-sectional structure in the width direction of the sample of the embodiment material E, and FIG. The crystal structure of the material E is shown.

  The implementation material E is a 0.26 mm diameter dilute copper alloy wire having an oxygen concentration of 7 mass ppm to 8 mass ppm, a sulfur concentration of 5 mass ppm, and a titanium concentration of 13 mass ppm. This execution material E is produced through an annealing treatment at an annealing temperature of 400 ° C. for 1 hour.

  The comparative material E is a 0.26 mm diameter wire made of oxygen-free copper (OFC). This comparative material E is produced through an annealing process at an annealing temperature of 400 ° C. for 1 hour.

[Relationship between crystal structure and conductivity of soft dilute copper alloy material]
As shown in FIG. 4 and FIG. 5, it can be seen that the crystal structure of the comparative material E is uniformly arranged with 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 E 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 this reason, compared with the comparative material E, the implementation material E is less obstructed by the flow of electrons when a current is passed, and the electrical resistance is reduced. Therefore, the conducting material E has a higher conductivity (% IACS) than the comparative material E.

  For this reason, when copper is annealed and the crystal structure is recrystallized, the recrystallized material E tends to advance, and the internal crystal grains grow greatly.

  Next, Table 2 shows the electrical conductivity of the working material E and the comparative material E.

[Relationship between crystal structure of soft dilute copper alloy material and annealing temperature]
Soft dilute copper alloy in which Ti of 13 mass ppm is added to Comparative material E using oxygen-free copper wire of 2.6 mm diameter and low oxygen copper of 2.6 mm diameter (oxygen concentration 7 mass ppm to 8 mass ppm, sulfur concentration 5 mass ppm) An implementation material E using a wire was used as a sample.

  FIG. 6 shows a cross-sectional photograph of the copper wire of the embodiment material E1 at an annealing temperature of 500 ° C. When FIG. 6 is seen, the fine crystal structure is formed in the whole cross section of a copper wire, and it seems that this fine crystal structure has contributed to the improvement of bending resistance.

  On the other hand, the cross-sectional structure of the comparative material E1 at the annealing temperature of 500 ° C. shown in FIG. 8 has undergone secondary recrystallization, and the crystal grains in the cross-sectional structure are coarser than the crystal structure of FIG. Yes.

  Moreover, FIG. 7 shows a cross-sectional photograph of the copper wire of the implementation material E2 at the 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.

  On the other hand, in the cross-sectional structure of the comparative material E1 shown in FIG. 8, crystal grains having substantially the same size are arranged uniformly from the surface to the center, and secondary recrystallization proceeds in the entire cross-sectional structure. .

  Thus, the proportion of the fine crystal layer in the wire cross section can be adjusted by adjusting the annealing temperature and the annealing time. The smaller the proportion of the fine crystal layer, the better the soft properties of the conductor. Can be made.

  As described above, in the embodiment material E, the surface layer has fine crystals, while the inner crystal grains become large and soft, so that the soft characteristics can be further improved.

(About 0.05 mm diameter conductor crystal structure)
The process up to producing a copper wire of φ2.6 mm size is the same as that of the soft dilute copper alloy material described above. This was subjected to wire drawing to φ0.9 mm, once annealed with a current-carrying annealer, and then drawn to φ0.05 mm.

  Next, running annealing was performed in a tubular furnace at 400 ° C. to 600 ° C. × 0.8 to 4.8 seconds, and the material for the material F was obtained. For comparison, 4N copper having a diameter of 0.05 mm (99.99% or more, OFC (oxygen-free copper)) was also produced under the same processing heat treatment conditions and used as a material for the comparative material F. The crystal grain size of these materials was measured.

  16 shows a cross-sectional structure in the width direction of the sample according to the comparative material F, and FIGS. 15A and 15B show cross-sectional structures in the width direction of the sample according to the embodiment material F. FIG.

  Referring to FIG. 16, it can be seen that in the crystal structure of Comparative Example F, crystal grains having the same size are arranged uniformly from the surface portion to the central portion. On the other hand, the crystal structure of the embodiment material F has a sparse crystal grain size as a whole, and the crystal grain size in the layer formed thin near the surface in the cross-sectional direction of the sample is larger than the internal crystal grain size. It is extremely small.

  The present inventor contributes to the fact that the fine crystal grain layer that appears in the surface layer that is not formed in Comparative Example F has the soft characteristics of the embodiment material F and has both tensile strength and elongation characteristics. thinking.

  Normally, it is understood that when heat treatment for softening is performed, crystal grains uniformly coarsened by recrystallization are formed as in the comparative material. However, in this embodiment, even if an annealing process for forming coarse crystal grains inside is performed, a fine crystal grain layer remains on the surface layer. Therefore, in the present embodiment example, it is considered that a soft dilute copper alloy material excellent in tensile strength and elongation despite being a soft copper material was obtained.

  Moreover, based on the cross-sectional photograph of the crystal structure shown in FIG.16 and FIG.15, the average crystal grain size in the surface layer of the sample concerning the implementation material F and the comparison material F was measured.

  FIG. 17 shows an outline of a method for measuring the average grain size in the surface layer.

  As shown in FIG. 17, in the range of 10 μm depth from the surface of the cross section in the width direction of 0.05 mm diameter in the depth direction to a depth of 10 μm, that is, up to 20% of the wire diameter and a length of 0.25 mm. The crystal grain size was measured. And the average value was calculated | required from each measured value (actually measured value), and this average value was made into the average crystal grain size.

  As a result of the measurement, the average crystal grain size in the surface layer of Comparative Example F was 22 μm, whereas the average crystal grain size in the surface layer of Example Material F was 7 μm and 15 μm, which were different. If the grain size is large, cracks develop along the grain boundaries. However, if the crystal grain size is small, the growth direction of the cracks changes, so that the growth is suppressed. From this, it is considered that the bending resistance of the implementation material F is superior to that of the comparative material F.

  While the embodiments and examples of the present invention have been described above, the embodiments and examples described above do not limit the invention according to the claims. It should be noted that not all combinations of features described in the embodiments and examples are necessarily essential to the means for solving the problems of the invention.

1 Bending head 2 Sample 3 Ring 4 Clamp 5 10 Bus bar

Claims (8)

  A wiring material that includes an additive element selected from the group consisting of Ti, Mg, Zr, Nb, Ca, V, Ni, Mn, and Cr, the balance is made of a soft dilute copper alloy that is made of copper, and has a bent portion. A wiring material using a soft dilute copper alloy, wherein the crystal structure of the wiring material is at least 20 μm or less in average grain size in the surface layer from the surface to a depth of 50 μm.   A wiring material that includes an additive element selected from the group consisting of Ti, Mg, Zr, Nb, Ca, V, Ni, Mn, and Cr, the balance is made of a soft dilute copper alloy that is made of copper, and has a bent portion. A wiring using a soft dilute copper alloy characterized in that the wiring material has a surface layer having an average crystal grain size of 15 μm or less from the surface to the depth of 20% of the wire diameter from the surface to the inside. Wood.   The soft dilute copper alloy according to claim 1 or 2, wherein the crystal structure of the wiring material is a recrystallized structure having a grain size distribution in which a crystal grain size is large inside and a crystal grain size is small in a surface layer. The wiring material used.   The soft diluted copper alloy according to any one of claims 1 to 3, wherein the soft diluted copper alloy contains 2 to 12 mass ppm of sulfur, 2 to 30 mass ppm of oxygen, and 4 to 55 mass ppm of Ti. Wiring material using.   A plate material including an additive element selected from the group consisting of Ti, Mg, Zr, Nb, Ca, V, Ni, Mn, and Cr, the balance being made of a soft dilute copper alloy consisting of copper, and having a bent portion, A plate material using a soft dilute copper alloy, wherein the crystal structure of the plate material is 20 μm or less in average grain size in the surface layer at least from the surface to a depth of 50 μm.   A plate material including an additive element selected from the group consisting of Ti, Mg, Zr, Nb, Ca, V, Ni, Mn, and Cr, the balance being made of a soft dilute copper alloy consisting of copper, and having a bent portion, A plate material using a soft dilute copper alloy, characterized in that the crystal structure of the plate material has a surface layer having an average crystal grain size of 15 μm or less from at least the surface toward the inside to a depth of 20% of the plate thickness.   The soft dilute copper alloy according to claim 5 or 6, wherein the crystal structure of the plate material is a recrystallized structure having a particle size distribution in which the crystal grain size is large inside and the crystal grain size is small in the surface layer. Board material.   8. The soft diluted copper alloy according to claim 5, wherein the soft diluted copper alloy contains 2 to 12 mass ppm of sulfur, 2 to 30 mass ppm of oxygen, and 4 to 55 mass ppm of Ti. Plate material using.