JP2004179151A - Copper alloy conductor and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper alloy conductor having both excellent strength and high conductivity, and a method for producing the same.
SOLUTION: Tin is contained in an amount of 0.05 to 0.80% by mass, and the remainder consists of unavoidable impurities and copper, and this tin exists in a state of tin alone and tin oxide, and the weight of tin component of tin oxide / the weight of tin alone. Is 0.3 or less. By reducing the percentage of tin oxide, the amount of effective tin contributing to an increase in tensile strength is increased, and the reduction in the total amount of tin required to obtain a specified tensile strength is suppressed, thereby suppressing a decrease in conductivity. I do. Therefore, a conductor having both high strength and electrical conductivity can be realized.
[Selection diagram] None

Description

  The present invention relates to a copper alloy conductor and a method for manufacturing the same. In particular, the present invention relates to a copper alloy conductor having excellent strength and conductivity and a method for producing the same.

  Conventionally, a so-called tough pitch copper wire has been known as a technique related to a copper alloy conductor (for example, see Patent Document 1). Tough pitch copper is generally copper containing 250 ppm (0.025%) or more of oxygen, and includes Ag, Ni, Sb, As, Fe, Sn, Pb, Bi, Si, S, and the like as impurities.

  In addition, a technique is known in which a predetermined element is added to copper to suppress disconnection during drawing (for example, see Patent Document 2).

Japanese Patent Publication No. 46-32333 JP-A-57-1562

  However, it is difficult to obtain a conductor having both strength and electrical conductivity in the above-described conventional technology.

  When tin is added to tough pitch copper or the like, the strength can be improved. However, when the oxygen content is large and the contained tin becomes tin oxide, the contribution to the increase in strength is reduced. Therefore, in order to obtain a desired strength, the tin concentration must be increased. However, there has been a problem that when the tin concentration is increased, the conductivity is reduced, and the electrical characteristics as a conductor are reduced.

  Therefore, a main object of the present invention is to provide a copper alloy conductor having both excellent strength and high electrical conductivity, and a method for producing the same.

  The present invention achieves the above object by limiting the tin concentration and specifying the ratio of the tin component of tin oxide present in the copper alloy to simple tin.

  That is, the copper alloy conductor of the present invention contains 0.05 to 0.80% by mass of tin, and the remainder is composed of unavoidable impurities and copper, and this tin exists in the form of tin alone and tin oxide, and the tin component in tin oxide The weight / weight of tin alone is 0.3 or less. Here, the tin component weight in tin oxide (Sn in SnO) is defined as tin (Sn) contained in the residue (SnO) remaining as an insoluble component when a copper alloy conductor is dissolved with 60% nitric acid. are doing.

  As described above, by specifying the tin concentration and the weight ratio of the tin component in tin oxide to the simple substance of tin, a copper alloy conductor having both strength and conductivity can be obtained. It can be suitably used as a conductor of wiring for use.

  Hereinafter, the present invention will be described in more detail.

If the tin concentration is less than 0.05% by mass, it is difficult to obtain a sufficient tensile strength. The preferred tensile strength of the conductor of the present invention is 550 N / mm ² or more, more preferably 600 N / mm ² or more, and further preferably 700 N / mm ² or more.

  Conversely, when the tin concentration exceeds 0.80% by mass, it is difficult to obtain a predetermined conductivity. The preferred electrical conductivity of the conductor of the present invention is 55% or more, more preferably 70% or more, and further preferably 80% or more. The conductivity is shown as a percentage (% IACS) at 20 ° C. with respect to the conductivity of standard annealed copper specified in the Universal Copper Standard.

  The chemical components of the copper alloy conductor of the present invention may contain unavoidable impurities. The inevitable impurities include Ag, Ni, Sb, As, Fe, Pb, Bi, P, Si, Zn, S, Se, Te, and the like.

  Further, the weight ratio between the tin component of tin oxide and the simple substance of tin is set to 0.3 or less. When this ratio exceeds 0.3, the tin concentration for obtaining a predetermined tensile strength becomes high, and the conductivity tends to decrease. The total tin weight of Sn and Sn alone in SnO is measured by emission spectro-photometric analysis. The weight of Sn alone is determined by dissolving a sample of a copper alloy conductor with 60% nitric acid to precipitate SnO and separating the solution, and subjecting the supernatant to atomic absorption spectrometry (Atomic Absorption Spectrometry) to measure the dissolved Sn. By subtracting the weight of Sn alone from the total tin weight, the weight of tin contained in SnO can be determined. This SnO is mainly generated by bonding with oxygen contained in molten copper in a solidification process during casting.

  The oxygen concentration in the copper alloy conductor of the present invention is preferably 0.08% by mass or less. If the oxygen concentration exceeds 0.08% by mass, the amount of SnO increases, which may hinder the drawability of the obtained conductor. A more preferred oxygen concentration is 0.04% by mass or less. The oxygen concentration can be measured, for example, by infrared absorption analysis (Infrared Spectrum Absorbance).

  Further, the average particle size of tin oxide contained in the copper alloy conductor of the present invention is preferably 10 μm or less. If the average particle size exceeds 10 μm, workability when drawing the obtained conductor to a small diameter may be affected. The average particle size of tin oxide can be measured using a scanning electron microscope (SEM) or an energy-dispersive X-ray spectroscopy (EDX). A more preferred average particle size of tin oxide is 5 μm or less.

  The above copper alloy conductor is preferably manufactured by the following method. That is, the method for producing a copper alloy conductor of the present invention includes a step of melting and casting a raw material containing 0.05 to 0.80% by mass of tin and the balance being inevitable impurities and copper, and a step of rolling the obtained ingot. And a cooling rate of 3 ° C./sec or more during solidification of the molten raw material in the casting step.

  By using a raw material having the above tin content and setting the cooling rate at the time of solidification of the molten raw material to 3 ° C./sec or more, a copper alloy conductor having a tin component weight of tin oxide / tin alone weight of 0.3 or less can be obtained. it can. If the cooling rate is less than 3 ° C./sec, the amount of generated tin oxide increases, leading to a decrease in conductivity. Usually, the upper limit of this cooling rate is about 50 ° C./sec.

  In general, a copper alloy conductor is obtained by a process of melting, casting, and hot (cold) rolling, and is drawn to a predetermined wire diameter as a subsequent process. Here, the cooling rate of the ingot after solidification to 200 ° C. through hot rolling or the cooling rate before cold rolling after casting is preferably 10 ° C./sec or more. By controlling to such a cooling rate, it is possible to keep the amount of generated tin oxide in an appropriate range and maintain high strength and electrical conductivity. If the cooling rate is less than 10 ° C./sec, tin diffuses into copper, increasing the amount of tin oxide produced, which leads to a decrease in conductivity.

  The copper alloy conductor of the present invention has a sufficient strength and can be used as a particularly small-diameter conductor. For example, a conductor having a wire diameter of 1.2 mm or less, or even 0.5 mm or less can be easily obtained.

  According to the copper alloy conductor of the present invention, by reducing the proportion of tin oxide, the effective tin amount contributing to an increase in tensile strength is increased, and the total tin amount required to obtain a predetermined tensile strength is reduced. By doing so, a decrease in conductivity is suppressed. Therefore, a conductor having both high strength and electrical conductivity can be realized.

  Further, the method for producing a copper alloy conductor of the present invention is a suitable production method for producing the conductor of the present invention.

  Hereinafter, embodiments of the present invention will be described.

(Example 1)
A copper alloy having a Sn content of 0.075% by mass and the balance consisting of Cu and unavoidable impurities was prepared, and a copper alloy conductor was produced using a process of “melting → casting → hot rolling → cold drawing”. For casting, a twin belt type casting machine was used.

  In this manufacturing process, the cooling rate during solidification was 5.77 ° C./sec, and the cooling rate after cooling to 200 ° C. (cooling rate during processing) was 21 ° C./sec.

  During the process, after rolling was completed, a sample was taken, and the total amount of Sn in the alloy was determined by emission spectroscopy (dry analysis). Next, this sample was dissolved in 60% nitric acid to dissolve the insoluble matter, and the supernatant was analyzed by atomic absorption analysis to determine the amount of dissolved Sn alone. The amount of Sn alone was subtracted from the total amount of Sn to obtain the amount of Sn in SnO. As a result, the value of Sn / Sn in SnO was 0.07. The cross section of the sample after rolling was observed using a scanning electron microscope (SEM), and the average particle size of SnO was 4 μm.

  When a sample was separately collected and the oxygen content was measured by infrared absorption analysis, it was 0.0230% by mass.

  The working ratio after the completion of the drawing was 99.75% (area reduction rate), and the final wire diameter was 0.4 mm. In addition, the present example and the comparative examples are combined, and the wire breakage rate during processing and the ease of processing at the time of thinning in the post-process are comprehensively determined and the workability is evaluated. 5, when the poor one was scored as 1, the example 1 was evaluated as 5.

Using this copper alloy conductor, the tensile strength and electrical conductivity were determined. The tensile strength was 552 N / mm ² and the electrical conductivity was 88.3% IACS.

(Example 2)
A copper alloy conductor was produced in the same process as in Example 1, except that a copper alloy having a Sn content of 0.624% by mass was used. However, the cooling rate during solidification was 3.2 ° C./sec, and the cooling rate during processing was 23 ° C./sec.

  The working ratio after the completion of the drawing was 99.75% (area reduction rate), and a final wire diameter of 0.4 mm was obtained. As in Example 1, after rolling in the middle of the process, a sample was taken, and the Sn / Sn in SnO was measured. The result was 0.28, and the average particle size of SnO was 12 μm. Further, the oxygen content was 0.0298% by mass.

The tensile strength of the obtained copper alloy conductor was 720 N / mm ² , and the electrical conductivity was 62.5% IACS. Further, the evaluation of workability was 2, which is considered to be because the particle size of SnO was increased.

  In addition, Example 2 contains more Sn than Examples 5 and 6 described below, but does not have a large tensile strength. This is probably because the particle size of SnO was increased.

(Example 3)
A copper alloy conductor was produced in the same process as in Example 1, except that a copper alloy having a Sn content of 0.187% by mass was used. However, the cooling rate during solidification was 3.9 ° C./sec, and the cooling rate during processing was 18 ° C./sec.

  The working ratio after the completion of the drawing was 99.75% (area reduction rate), and a final wire diameter of 0.4 mm was obtained.

  As in Example 1, after rolling in the middle of the process, a sample was taken, and the Sn / Sn in SnO was measured. The result was 0.18, and the average particle size of SnO was 6 μm. Further, the oxygen content was 0.0820% by mass.

The tensile strength of the obtained copper alloy conductor was 595 N / mm ² , and the electrical conductivity was 82.6% IACS. The evaluation of workability was 4.

Example 3 contains more Sn than the following Example 4, but has a higher oxygen content than Example 4, so the amount of SnO increases, and the tensile strength becomes smaller than that of Example 4. It is thought that it became the value.
(Example 4)
A copper alloy conductor was produced in the same process as in Example 1, except that a copper alloy having a Sn content of 0.177% by mass was used. However, the cooling rate during solidification was 5.47 ° C./sec, and the cooling rate during processing was 18 ° C./sec.

  The working ratio after the completion of the drawing was 99.75% (area reduction rate), and a final wire diameter of 0.4 mm was obtained.

  As in Example 1, after rolling in the middle of the process, a sample was taken, and the Sn / Sn in SnO was measured. The result was 0.07, and the average particle size of SnO was 6 μm. Further, the oxygen content was 0.0350% by mass.

The obtained copper alloy conductor had a tensile strength of 610 N / mm ² and a conductivity of 82.8% IACS. It became a very well-balanced material. The workability was very good, and the evaluation was 5.

(Example 5)
A copper alloy conductor was produced in the same process as in Example 1, except that a copper alloy having a Sn content of 0.315% by mass was used. However, the cooling rate during solidification was 5.47 ° C./sec, and the cooling rate during processing was 8 ° C./sec.

  The working ratio after the completion of the drawing was 99.75% (area reduction rate), and a final wire diameter of 0.4 mm was obtained.

  As in Example 1, after rolling in the middle of the process, a sample was taken, and the Sn / Sn in SnO was measured. The result was 0.11, and the average particle size of SnO was 5 μm. Further, the oxygen content was 0.0410% by mass.

The tensile strength of the obtained copper alloy conductor was 700 N / mm ² , and the electrical conductivity was 76.8% IACS. The evaluation of workability was 3. This is thought to be due to the cooling rate during processing.

  Further, in Example 5, although the content of Sn was slightly lower than that of Example 6, the conductivity was not larger than that of Example 6. It is considered that the reason for this is that the cooling rate during processing was 10 ° C./second or less, and Sn diffused into Cu to form SnO, so that the electrical conductivity decreased.

(Example 6)
A copper alloy conductor was produced in the same process as in Example 1, except that a copper alloy having a Sn content of 0.338% by mass was used. However, the cooling rate during solidification was 5.47 ° C./sec, and the cooling rate during processing was 23 ° C./sec.

  The working ratio after the completion of the drawing was 99.75% (area reduction rate), and a final wire diameter of 0.4 mm was obtained.

  As in Example 1, after rolling in the middle of the process, a sample was taken, and the Sn / Sn in SnO was measured. The result was 0.07, and the average particle size of SnO was 4 μm. Further, the oxygen content was 0.0215% by mass.

The obtained copper alloy conductor had a tensile strength of 710 N / mm ² and a conductivity of 78.0% IACS. The workability was evaluated as 4.

(Comparative Example 1)
A copper alloy conductor was produced in the same process as in Example 1, except that a copper alloy having a Sn content of 0.030% by mass was used. However, the cooling rate during solidification was 5.47 ° C./sec, and the cooling rate during processing was 18 ° C./sec.

  The working ratio after the completion of the drawing was 99.75 (area reduction ratio), and a final wire diameter of 0.4 mm was obtained.

  As in Example 1, after rolling in the middle of the process, a sample was taken, and the Sn / Sn in SnO was measured. The result was 0.03, and the average particle size of SnO was 3 μm. Further, the oxygen content was 0.0240% by mass.

The tensile strength of the obtained copper alloy conductor was 535 N / mm ² , and the electrical conductivity was 97.8% IACS. Since Comparative Example 1 is a material close to pure copper, the conductivity shows a large value, but a sufficient tensile strength cannot be obtained. Further, the workability was no problem and was evaluated as 5.

(Comparative Example 2)
A copper alloy conductor was produced in the same process as in Example 1, except that a copper alloy having a Sn content of 0.680% by mass was used. However, the cooling rate during solidification was 2.1 ° C./sec, and the cooling rate during processing was 23 ° C./sec.

  The working ratio after the completion of the drawing was 99.75% (area reduction rate), and a final wire diameter of 0.4 mm was obtained.

  As in Example 1, after rolling in the middle of the process, a sample was taken, and the Sn / Sn content in SnO was measured. The result was 0.37, and the average particle size of SnO was as large as 20 μm. Further, the oxygen content was 0.0850% by mass.

Although the tensile strength of the obtained copper alloy conductor was 710 N / mm ² , the electrical conductivity was reduced to 52.5% IACS. Since this material has a high Sn content, it has a high tensile strength, but has a somewhat insufficient electrical conductivity. In addition, the workability was evaluated as 1 because the disconnection rate in the subsequent process was increased. It is considered that the SnO particle size became large.

  As shown in the above Examples and Comparative Examples, all Examples have both high tensile strength and high electrical conductivity. Further, when the Sn content in the raw material itself is not in the preferable range as in Comparative Example 1, the tensile strength and the electrical conductivity are not compatible regardless of the processing conditions. Also, if Sn / Sn in SnO exceeds 0.3, the tensile strength and the electrical conductivity are similarly incompatible.

  By specifying the tin concentration and the weight ratio of the tin component in the tin oxide to the simple tin, it is possible to obtain a copper alloy conductor having both strength and electrical conductivity, particularly as a conductor for wiring for electronic devices and wiring for automobiles. It can be suitably used.

Claims (5)

Tin is contained in an amount of 0.05 to 0.80% by mass, and the remainder consists of unavoidable impurities and copper, and this tin exists in a state of tin alone and tin oxide,
A copper alloy conductor, wherein the ratio of tin component weight in tin oxide / tin alone weight is 0.3 or less.   2. The copper alloy conductor according to claim 1, wherein the oxygen concentration is 0.08% by mass or less.   3. The copper alloy conductor according to claim 1, wherein the average particle size of the tin oxide is 10 μm or less. Melting and casting a raw material containing 0.05 to 0.80 mass% of tin and the balance being inevitable impurities and copper;
Rolling the obtained ingot,
A method for producing a copper alloy conductor, wherein a cooling rate is set to 3 ° C./second or more during solidification of a molten raw material in the casting step.   The method for producing a copper alloy conductor according to claim 4, wherein a cooling rate at which the ingot after solidification reaches 200 ° C is 10 ° C / second or more.