JP2006156129A - Method for manufacturing copper or copper alloy extrafine wire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a copper or copper alloy extrafine wire which can not be broken easily while being drawn to a diameter of less than 30 μm. <P>SOLUTION: In case that a copper alloy extrafine wire having a diameter of less than 30 μm is manufactured from a base material, having a length of T (mm), of a copper alloy: at first, an inside of a reaction tube 1 is exhausted to a pressure of approximately 1×10<SP>-1</SP>Pa by a rotary pump; a raw material 5 is melted by heating whole of a crucible 3, filled with prescribed amount of copper wire and silver wire, to a temperature of 1,200°C by a heating element 4; and foreign matters like SiO<SB>2</SB>, Al<SB>2</SB>O<SB>3</SB>or the like, included in the raw material 5, is floated by keeping a melted raw material being heated at a temperature of 1,200°C and for a period more than (T/15) hours. Thereafter, the heating element 4 is transferred upward along the reaction tube 1 with a speed of 5 to 50 mm/min, and a base material of the copper alloy is obtained by coagulating the melted material in one direction. After an upper part, containing the foreign matters, of the base material of the copper alloy is removed, a copper alloy fine wire is obtained by drawing. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a copper or copper alloy fine wire having a diameter of less than 30 μm used for a fine coaxial cable of a small electronic device such as a mobile phone.

  Recently, with the miniaturization and weight reduction of electronic devices, the demand for ultra-fine coaxial cables with excellent electrical characteristics is increasing. At present, micro coaxial cables using strands having a diameter of 25 to 30 μm are generally used for small electronic devices such as mobile phones. However, such electronic devices are being further miniaturized. Coaxial cables are also required to be thin.

In order to make a coaxial cable thinner, it is necessary to make the strands of the coaxial cable thinner. Conventionally, in copper or copper alloy ultrafine wires used as coaxial cable strands, copper produced by the SCR (Southwire Conti-Rod: continuous casting and rolling) method, beltley, continuous casting machine, etc. as a base material Alternatively, a copper alloy wire that has been processed into a diameter of 6 to 8 mm and then removed from the surface layer by a peeling die is used. However, since the foreign material on the surface layer is removed from the base material of the ultrathin wire manufactured by such a method, the foreign material existing inside is not removed. Therefore, using a drawing die so that the diameter is less than 30 μm. When the wire drawing is performed, wire breakage occurs frequently due to furnace materials such as SiO ₂ and Al ₂ O ₃ mixed at the time of forming the base material and foreign matters such as Fe powder mixed in the wire drawing process, resulting in a decrease in manufacturing efficiency. . In view of this, conventionally, a method of manufacturing an ultrafine wire by reducing the diameter of a base material by pickling has been proposed (see Patent Documents 1 and 2).

Japanese Patent No. 2714922 JP 2002-140935 A

  However, the conventional techniques described above have the following problems. That is, as described in Patent Documents 1 and 2, when the base material is processed into a fine wire by pickling, there is a problem that the processing speed is slow and the production efficiency is low. For this reason, in the manufacturing process of ultrafine wires, a method of drawing a base material to make ultrafine wires is frequently used, and even if wiredrawing is performed so that the diameter is less than 30 μm, disconnection hardly occurs. There is a need for a copper or copper alloy matrix.

  This invention is made | formed in view of this problem, Comprising: It aims at providing the manufacturing method of the copper or copper alloy extra fine wire which is hard to generate | occur | produce a disconnection even if it draws to less than 30 micrometers in diameter.

  The method for producing a copper or copper alloy fine wire according to the present invention is a method for producing a copper or copper alloy fine wire having a diameter of less than 30 μm from a copper or copper alloy base material having a length of T (mm). A step of melting a raw material including an alloy material and holding it in a molten state for (T / 15) hours or more, and solidifying the molten raw material from below to above by a unidirectional solidification method to form copper or a copper alloy The method includes a step of obtaining a base material, and a step of drawing the unidirectionally solidified copper or copper alloy base material.

  In the present invention, by holding the raw material in a molten state for (T / 15) hours or more, the foreign matter contained in the raw material is levitated, and then solidified from below to above by a unidirectional solidification method. Since the copper or copper alloy base material excluded as much as possible is used, it is possible to reduce the occurrence rate of disconnection when the wire is drawn into an ultrafine wire having a diameter of less than 30 μm.

  In this method of manufacturing a copper or copper alloy ultrafine wire, the solidification rate of unidirectional solidification can be 5 to 50 mm / min. Thereby, it can prevent that an alloy component segregates in copper or a copper alloy base material, or when a raw material solidifies, a dent is generated and a foreign material is drawn into the inside of a copper or copper alloy base material. In addition, the copper or copper alloy base material may be drawn after a predetermined length of the upper portion is removed after unidirectional solidification.

  According to the present invention, after the foreign material contained in the raw material is levitated by holding the raw material in a molten state for a predetermined time or more, the foreign material is removed by solidification by a unidirectional solidification method. Since the wire is used, it is possible to reduce the occurrence rate of disconnection when the wire is drawn into an extra fine wire.

  Hereinafter, the manufacturing method of the copper or copper alloy extra fine wire which concerns on embodiment of this invention is demonstrated concretely with reference to attached drawing. In order to solve the above-mentioned problems, the present inventors conducted extensive experimental research. As a result, the raw material was mixed in the raw material by holding it in a molten state for a certain period of time and then solidifying it using a unidirectional solidification method. It was found that the foreign material that had been collected can be collected on the upper part of the solidified material, and by removing the portion containing the foreign material, a copper or copper alloy base material having excellent wire drawing workability to ultrafine wires can be obtained. .

Therefore, in the manufacture of the copper fine wire of the present embodiment, a copper or copper alloy base material is manufactured using a unidirectional solidification method. FIG. 1 is a cross-sectional view schematically showing a unidirectional solidification apparatus used in the method for producing a copper fine wire according to the present embodiment. As shown in FIG. 1, a directional solidification apparatus 10 used in the present embodiment is provided with a reaction tube 1 made of quartz or the like, and on an installation table 2 provided in the reaction tube 1, A crucible 3 filled with the raw material 5 is placed. A heating element 4 made of Si ₃ N ₄ or the like is disposed around the reaction tube 1. The heating element 4 has a size capable of heating the entire crucible 3 and is movable in the vertical direction along the reaction tube 1. By using this unidirectional solidification apparatus 10, it is possible to generate a suitable temperature distribution in the melted raw material and solidify in one direction.

Next, a method for producing a copper or copper alloy base material having a length of Tmm using the unidirectional solidification apparatus 10 will be described. First, the crucible 3 is filled with a copper material such as a copper wire as a raw material 5 and, if necessary, an additive component material such as a silver wire. And the heat generating body 4 is arrange | positioned in the position which can heat the whole rutuho 3, and the inside of the reaction tube 1 is evacuated to about 1 * 10 < ^-1 > Pa with a rotary pump (not shown) etc., for example. While maintaining this degree of vacuum, the entire crucible 3 is heated by the heating element 4 to the melting point of the raw material 5 or higher, for example, 1100 ° C. or higher, to melt the raw material 5 and kept under this temperature condition for (T / 15) hours or longer. To do. That is, after the raw material 5 is melted, it is held in a molten state for (T / 15) hours or more. Thus, foreign matter such as SiO ₂ and _Al 2 _{O 3} contained in the raw material 5 floats.

  Thereafter, the heating element 4 is moved upward along the reaction tube 1 at a speed of 5 to 50 mm / min. Then, the molten metal in the crucible 3 is continuously removed upward from the lower portion thereof from the heating area by the heating element 4, and the molten metal in the crucible 3 outside the heating area is cooled down, and the freezing point If it exceeds, it will solidify. Then, by moving the heating element 4 upward, the molten metal in the crucible 3 is solidified while moving upward with the solidification interface being substantially horizontal. Thereby, copper or a copper alloy is unidirectionally solidified. In this unidirectional solidification, the solidification interface is substantially horizontal and no shrinkage cavity is generated, so that no foreign matter is taken into the center of the ingot. Then, foreign matters accumulate on the upper part of the copper or copper alloy base material that has finally been solidified. Therefore, when the upper part where the foreign matter is accumulated is cut off, the remaining copper or copper alloy base material portion contains almost no foreign matter and has high cleanliness. Therefore, when this copper or copper alloy base material is drawn into an extra fine wire, disconnection is prevented and a high quality extra fine wire can be obtained.

  Next, the reason for the numerical limitation in the method for manufacturing the copper or copper alloy fine wire of the present embodiment will be described.

Time for holding the raw material in the molten state: When producing a copper or copper alloy base material having a length of Tmm or more for T / 15 hours or more, when the time for holding the raw material in the molten state is shorter than (T / 15) time, The foreign matter does not sufficiently float and remains in the solidified copper or copper alloy base material. Therefore, the time for holding the raw material in a molten state is (T / 15) hours or more. In addition, although the upper limit of the time which hold | maintains a raw material in a molten state is not specifically limited, when productivity is considered, it is preferable to set it as 20 hours or less.

Heating element moving speed (unidirectional solidification speed): 5 to 50 mm / min When the heating speed of the heating element 4 is less than 5 mm / min, when producing a copper alloy base material such as a Cu-Ag alloy material, etc. The alloy components may segregate. Moreover, when the moving speed of the heating element 4 exceeds 50 mm / min, a nest is generated during solidification, and foreign matter may be drawn into the copper or copper alloy base material. Therefore, the moving speed of the heating element 4 is preferably 5 to 50 mm / min. If the moving speed of the heating element is about this level, the moving speed of the heating element substantially coincides with the solidification speed during unidirectional solidification.

Hereinafter, the effect of the present invention will be described in comparison with a comparative example that is out of the scope of the present invention. As a first example of the present invention, a Cu-Ag alloy base material was produced using the unidirectional solidification apparatus shown in FIG. First, after filling the crucible 3 with a copper wire having a diameter of 8 mm and a silver wire having a purity of 99.99% by mass produced by the SCR method, the inside of the reaction tube 1 is about 1 × 10 ⁻¹ Pa by a rotary pump. A vacuum was drawn. And while maintaining this degree of vacuum, the whole crucible 3 was heated to 1200 ° C. by the heating element 4 to melt the raw material 5, and further this molten raw material 5 was held at 1200 ° C. for 10 hours. Thereafter, the heating element 4 was moved upward at a speed of 10 mm / min to produce a unidirectional solidified material having a diameter of 30 mm and a length T of 150 mm and made of a Cu—Ag alloy. When the Ag concentration of this unidirectionally solidified material was analyzed by EPMA (Electron Probe X-ray microanalyzer), the upper part was 1.1%, the central part was 0.9%, and the lower part was 1.0%. A uniformly distributed Cu-Ag alloy base material could be produced.

  Further, as a comparative example of the present invention, a Cu—Ag alloy base material having the same composition as the unidirectional solidified material of the above-described example was manufactured by the SCR method. And the wire drawing process was performed with respect to the unidirectional solidification material of an Example, and the SCR material of a comparative example, and the drawability was evaluated. At that time, the SCR material of the comparative example was drawn to a diameter of 6.5 mm, and then peeled to remove the surface layer with a peeling die, and further, the diameter was 2.0 mm with a single-head wire drawing machine. The wire was drawn until Then, using a triple wire drawing machine, the wire was drawn until the diameter became 0.9 mm. After that, using a cone-type slip wire drawing machine, the inlet diameter was 0.9 mm and the outlet diameter was Is 0.12 mm, the inlet diameter is 0.12 mm, the outlet diameter is 0.05 mm, the inlet diameter is 0.05 mm, the outlet diameter is 0.03 mm, the inlet diameter is 0.03 mm, and the outlet diameter is 0 The dies having a diameter of .015 mm were arranged in this order and drawn. The wire drawability was evaluated by measuring the number of breaks when the wire was processed to a diameter of 0.015 mm when the wire rod had a diameter of 0.12 mm and the length was 1000 m. On the other hand, the unidirectionally solidified material of Example was cut by removing the portion from the top to 50 mm, which seems to have a large amount of foreign matter, and then reduced in diameter to 8.0 mm by the swaging method. The wire was drawn by the same method as that of the SCR material of the comparative example, and the drawability was evaluated.

  Moreover, the tensile test was done with respect to each wire after drawing based on the method prescribed | regulated to JIS specification C3002, and the tensile strength and elongation were measured. The above results are summarized in Table 1 below.

As shown in Table 1 above, there was almost no difference between the SCR material (Comparative Example 1) and the unidirectional solidified material (Example 1) in terms of wire drawing up to 0.03 mm (30 μm) in diameter. When the wire was drawn to a diameter of 0.015 mm (15 μm), the number of disconnections was 15 in the SCR material (Comparative Example 2), whereas the number of disconnections in the unidirectional solidified material (Example 2) was It was once and the number of disconnections was greatly reduced. Further, when the fracture surface was observed in order to investigate the cause of the disconnection, foreign matters such as SiO ₂ and Al ₂ O ₃ were detected in the wires of Comparative Example 1 and Comparative Example 2, but Example 1 No foreign matter was detected in the wires 2 and 2. From this, the SCR material (Comparative Example 1 and Comparative Example 2) was disconnected mainly due to the remaining foreign matter, and the unidirectional solidified material (Examples 1 and 2) was disconnected due to a cause other than the remaining foreign matter. it is conceivable that. Moreover, although the elongation of the wire of Examples 1 and 2 was equivalent to the wire of Comparative Examples 1 and 2, the tensile strength was improved. As described above, the unidirectionally solidified material of this example had fewer foreign matters inside than the SCR material of the comparative example, and was excellent in drawability and strength.

  Next, as a second embodiment of the present invention, the time for holding the raw material in the molten state was changed, and the time for holding the raw material in the molten state and the effect of floating separation of the foreign matters were examined. In this example, the unidirectional solidification apparatus shown in FIG. 1 is used, the temperature when the raw material is held in a molten state is 1200 ° C., the time is 1 hour, 5 hours, 10 hours, and 20 hours, respectively. These conditions were the same as in the first embodiment, and a unidirectionally solidified material made of a Cu—Ag alloy having a diameter of 30 mm and a length T of 150 mm was prepared. And by the same method as the above-mentioned 1st Example, the drawability of these unidirectional solidification materials and the tensile strength and elongation of each wire after drawing were evaluated. The results are shown in Table 2 below.

  As shown in Table 2 above, the unidirectionally solidified material (Comparative Examples 3 to 6) in which the raw material is held in the molten state (T / 15) time, that is, shorter than 10 hours, holds the raw material in the molten state. The number of breaks was greater than that of the unidirectionally solidified material (Examples 3 to 6) in which the time to be used was 10 hours or more. In particular, when the diameter is 0.015 mm (15 μm), the number of breaks is 9 times for the one-way solidified material (Comparative Example 4) in which the raw material is held in the molten state for 1 hour, and the raw material is held in the molten state. Whereas the unidirectional solidified material (Comparative Example 6) was 6 times in 5 hours, the unidirectional solidified material (Example 4 and Example 6) in which the raw material was kept in a molten state for 10 hours or longer. ) In all cases, the number of disconnections was greatly reduced.

Further, when the fracture surface was observed in order to investigate the cause of the disconnection, foreign substances such as SiO ₂ and Al ₂ O ₃ were detected in the wires of Comparative Examples 3 to 6, but Examples 3 to 6 No foreign matter was detected in the wire. Thereby, in the unidirectionally solidified material (Comparative Examples 3 to 6) in which the raw material is kept in a molten state for less than 10 hours, the time for which the raw material is held in a molten state is broken mainly due to the remaining foreign matter. In the unidirectionally solidified material (Examples 3 to 6), it is considered that the wire was disconnected due to a cause other than the remaining foreign matter. From this result, it was confirmed that a clean Cu—Ag alloy material with a small amount of foreign matter can be produced by sufficiently raising the foreign matter by setting the time for holding the raw material in a molten state to (T / 15) time or longer. From the results of this example, it is considered that the flying speed of the foreign matter is approximately 15 mm / hour.

  Further, in this example, even if the time for holding the raw material in the molten state was longer than 10 hours, there was no significant change in the number of breaks. This is considered to suggest that the foreign matter completely floats by holding the raw material in a molten state for a predetermined time or more. Furthermore, the tensile strength and elongation of each wire were substantially the same regardless of the time during which the raw material was kept in the molten state.

  Next, as a third embodiment of the present invention, the unidirectional solidification apparatus shown in FIG. 1 is used, the temperature at which the raw material is held in a molten state is 1200 ° C., the time is 1 hour, 10 hours, 20 hours, and The other conditions were the same as in the first embodiment, and a unidirectional solidified material made of a Cu-Ag alloy having a diameter of 30 mm and a length T of 300 mm was prepared as a copper alloy base material. . And the wire drawing property of these unidirectionally solidified materials and the tensile strength and elongation of each wire material after wire drawing were evaluated by the same method as in the first and second examples. The results are shown in Table 3 below.

  As shown in Table 3 above, the unidirectionally solidified material (Comparative Examples 7 to 10) in which the raw material is held in the molten state (T / 15) time, that is, shorter than 20 hours, holds the raw material in the molten state. The number of breaks was greater than that of the unidirectionally solidified material (Examples 7 to 10) in which the time to be used was 20 hours or more. In particular, when the diameter is 0.015 mm (15 μm), the number of breaks is 12 times for the one-way solidified material (Comparative Example 8) in which the raw material is held in the molten state for 1 hour, and the raw material is held in the molten state. Whereas the unidirectional solidified material (Comparative Example 10) was 10 times in time, the unidirectional solidified material (Example 8 and Example 10) in which the time for holding the raw material in a molten state was 20 hours or more. ) In all cases, the number of disconnections was greatly reduced.

Moreover, in order to investigate the cause of disconnection, the fracture surface of each wire was observed, and in the wires of Comparative Examples 7 to 10, foreign substances such as SiO ₂ and Al ₂ O ₃ were detected. No foreign matter was detected in the 7 to 10 wires. Therefore, in the unidirectionally solidified material (Comparative Examples 7 to 10) in which the raw material is held in a molten state for less than 20 hours, the breakage is mainly caused by residual foreign matter, and the raw material is held in a molten state for 20 hours or more. In a certain unidirectional solidified material (Examples 7 to 10), it is considered that the wire was disconnected due to a cause other than the remaining foreign matter. From this result, it was confirmed that by setting the time for holding the raw material in a molten state to (T / 15) time or more, a foreign material can sufficiently float and a clean Cu-Ag alloy base material with few foreign materials can be produced. . Also in this example, there was no significant change in the number of breaks even when the time for holding the raw material in the molten state was longer than 20 hours. Furthermore, the tensile strength and elongation of each wire were substantially the same regardless of the time during which the raw material was kept in the molten state.

  The manufacturing method of the copper or copper alloy extra fine wire of this invention is suitable when manufacturing the strand for ultra fine coaxial cables whose diameter used for a mobile telephone etc. is less than 30 micrometers.

It is sectional drawing which shows typically the unidirectional solidification apparatus used for the manufacturing method of the copper or copper alloy ultrafine wire which concerns on embodiment of this invention.

Explanation of symbols

1; reaction tube 2; installation base 3; crucible 4; heating element 5; raw material 10;

Claims (3)

In a method for producing a copper or copper alloy ultrafine wire having a diameter of less than 30 μm from a copper or copper alloy base material having a length of T (mm), a raw material containing a material made of copper or a copper alloy is melted and melted ( T / 15) a step of holding for a period of time, a step of solidifying the molten raw material from below to above by a unidirectional solidification method to obtain a copper or copper alloy base material, and this unidirectionally solidified copper or copper And a step of drawing an alloy base material. A method for producing a copper or copper alloy ultrafine wire. The method for producing a copper or copper alloy fine wire according to claim 1, wherein the solidification rate of the unidirectional solidification is 5 to 50 mm / min. The method for producing a copper or copper alloy fine wire according to claim 1 or 2, wherein the copper or copper alloy base material is subjected to wire drawing after removing a predetermined length of the upper portion after unidirectional solidification.

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