JP3324228B2 - Copper wire for ultrafine wire and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper wire for a fine wire used as a copper conductor for windings of electric / electronic devices, watches and the like, and a method of manufacturing the same. The present invention relates to a copper wire for an ultrafine wire having improved mechanical properties and drawability, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, copper conductors for windings of electric / electronic devices, watches and the like have become increasingly finer in line with the miniaturization and weight reduction of the devices. Demand is also rising.

[0003] The ultrafine copper wire is obtained by fine wire processing such as wire drawing. At this time, a disconnection is apt to occur due to an impurity element present in a trace amount in the copper wire or the effect of coarsening of crystal grains. For this reason, there is a demand for a copper wire material for a copper wire for an ultrafine wire to have more excellent processing performance and to have high strength and high conductivity.

Conventionally, oxygen-free copper (OFC) whose surface is peeled and cleaned and tough pitch copper (TPC) are often used for this kind of ultrafine wire.

[0005]

However, according to the ultrafine copper wire using oxygen-free copper or tough pitch copper, disconnection is likely to occur at the time of wire drawing due to the influence of the above-described impure elements and coarsening of crystal grains. In this case, it is difficult to draw wires with extremely small thickness, and the work yield is reduced. Further, since the softening temperature of these pure copper wires is low, the wire material changes from a semi-softened state to a completely softened state depending on the baking temperature at the time of enamel coating, so that desired strength properties, particularly, tensile properties cannot be obtained. Therefore, a copper wire for an ultrafine wire having excellent mechanical properties and conductivity is desired.

Accordingly, it is an object of the present invention to provide a copper wire for an ultrafine wire, which can improve mechanical properties without significantly lowering the conductivity and improve the yield by improving drawability.
And a method for producing the same.

[0007]

SUMMARY OF THE INVENTION In view of the above problems, the present invention improves the mechanical properties without significantly lowering the electrical conductivity, and improves the drawability by improving the drawability. 7 to 100p for 9 to 99.99% copper
It is composed of copper wire to which pm sulfur is added.
An object of the present invention is to provide an ultrafine copper wire having the following crystal grain size . The unit of purity “%” and the content “p”
pm ”are based on commonly used weights.
In the present specification, the explanation display is omitted.
You.

The above-mentioned copper wire is processed at a working ratio of 90% or more without performing an intermediate heat treatment after the solution treatment, and thus has a crystal grain size of 30 μm or less after the tempering treatment.

Further, a method for producing a copper wire for ultrafine wires according to the present invention, which achieves the above object, comprises adding 7 to 100 ppm of sulfur to molten copper having a purity of 99.9 to 99.99%, and continuously casting the material. Is produced in a solid solution state of sulfur, and the cast material is subjected to cold drawing at a working ratio of 90% or more without performing intermediate heat treatment, and then annealed to form a copper wire having a crystal grain size of 30 μm or less.
Performed by.

Here, the sulfur content is 7 to 100 ppm.
The reason is generally that oxygen-free copper contains 5 to 5 sulfur.
Although 7 ppm is contained, the crystal grain size is often non-uniform, and if the added amount of S is 7 ppm or less, a sufficient effect of crystal grain refinement cannot be obtained. As a result, sulfur segregation is apt to occur, leading to a decrease in fine workability and a decrease in conductivity. In addition, processing degree 80%
Below, a uniform grain size is not obtained, and a mixed grain is formed. That is, if the degree of processing is low, the number of nucleation sites for recrystallization is reduced, and it is not possible to obtain sufficiently fine crystal grains.

Therefore, sulfur is added to high-purity copper in an amount of 7 to 100 pp.
m and cast without adding intermediate heat treatment
By processing at a working ratio of 90%, the maximum crystal grain size after the tempering heat treatment of the final processing size can be made a uniform fine crystal grain size of 30 μm or less, and as a result, the conductivity is significantly reduced. The mechanical properties can be improved without the need.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The copper wire for extra fine wires of the present invention will be described in detail below.

[0013] First, in a small continuous casting apparatus, purity 99.995% of oxygen-free copper (OFC) was dissolved by a high-frequency vacuum melting (5 × 10 ^-4 Torr) as the copper base material, Cu-
This S component in the S master alloy is in a solid solution state,
S was added to the molten copper to cast a casting rod having an outer diameter of 8 mm.

Subsequently, the cast rod was cold drawn, and the wire diameter was 3 mm.
After forming a fine line of 0 μm, 100 μm in an inert gas atmosphere.
Tempering treatment is performed by performing continuous annealing in a temperature range of up to 400 ° C. In this way, ultrafine wires containing S in different amounts and the balance being copper were prepared as Examples 1 to 4.

On the other hand, an ultra-fine wire obtained by adding 5 ppm of S to oxygen-free copper having a purity of 99.99% is referred to as Comparative Example 1, and an ultra-fine wire obtained by adding 4 ppm of S to a tough pitch copper having a purity of 99.9% is referred to as Comparative Example 2. Each was created as.

Next, Examples 1 to 4 and Comparative Examples 1 and 2
In comparison, the electrical conductivity of the material, the maximum crystal grain size in the cross section in the longitudinal direction, and the tensile properties at room temperature were measured. Table 1 shows the measurement results. Here, the material conductivity shows the measurement results in the state of the cast rod before cold drawing, and the tensile properties show the measurement results at an elongation of 10%.

[Table 1]

As can be seen from the measurement results in Table 1, regarding the tensile properties after the tempering treatment, the extra fine wire of Comparative Example 1 was 26 kgf.
/ Mm ² , the fineness of Comparative Example 2 is 21.5 kgf / mm ²
On the other hand, the fine lines of Examples 1 to 4 are 27.0 to 3
3.5 kgf / mm ² , which is higher than Comparative Examples 1 and 2. That is, although the material conductivity tends to slightly decrease as the S content increases, the tensile properties are improved and the mechanical strength is improved as the crystal grain size is reduced.

As described above, the ultrafine copper wire of the present invention is cast by adding sulfur to high-purity copper in the range of 7 to 100 ppm, and is processed at a processing rate of 90% without intermediate heat treatment. In this case, the maximum grain size after the tempering heat treatment of the final processing size can be a uniform fine grain size of 30 μm or less, and as a result, the mechanical properties can be reduced without significantly lowering the conductivity. Can be improved.

In the embodiment described above, the wire diameter is set to 30 μm.
Although m is not particularly limited, it can be arbitrarily selected from 10 to 100 μm depending on the size used for an electronic device or the like. Further, in addition to oxygen-free copper, tough pitch copper can also be expected to improve characteristics by adding S.

[0020]

As described above, according to the ultrafine copper wire of the present invention and the method for producing the same, the purity is 99.9 to 9
To 9.99% copper, add 7-100 ppm sulfur,
In addition, since this is processed at a high working ratio of 90% or more to reduce the crystal grain size after the tempering treatment to 30 μm or less, the mechanical properties are improved without significantly lowering the conductivity, and the wire drawing workability is improved. Thereby, the yield can be improved.

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C22F 1/00 630 C22F 1/00 630A 630K 661 661A 686 686A 691 691B 694 694A (72) Inventor Takashi Nemoto Hidaka, Hitachi City, Ibaraki Prefecture 5-1-1, Hitachi-cho, Hitachi, Ltd. Power System Research Laboratories (72) Inventor Hiroyoshi Hiruta 4-1-1, Kawajiri-cho, Hitachi-shi, Ibaraki Pref. JP-A-2-163330 (JP, A) JP-A-56-139643 (JP, A) JP-A-2-22431 (JP, A) JP-A-2-22432 (JP, A) JP-A-6-2058 (JP , A) (58) Fields studied (Int. Cl. ⁷ , DB name) C22C 9/00 C22F 1/00-3/02 H01B 1/02

Claims (2)

(57) [Claims] (1) copper having a purity of 99.9 to 99.99%;
It is composed of a copper wire to which 100 ppm of sulfur is added.
An ultrafine copper wire having a crystal grain size of 0 μm or less. 2. A molten copper having a purity of 99.9 to 99.99% and a content of 7 to 9%.
100 ppm of sulfur is added, a cast material is produced by continuous casting, the sulfur is dissolved, and the cast material is subjected to cold drawing at a workability of 90% or more without being subjected to intermediate heat treatment. /> method for producing a fine wire copper wire, characterized in that a copper wire having a grain size less lines have 30 [mu] m.