JPS6340209A - Very fine wire for electronic equipment - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to ultra-fine wires for electronic devices, and particularly to ultra-fine wire conductors with low conductor resistance and used as high-quality winding wires, bonding wires, etc. be.

[Conventional technology]

Ultrafine wire conductors used as winding wires, bonding wires, etc. are conventionally manufactured using water-cooled molds.
It was manufactured by hot working a tough pitch copper ingot containing 500 ppm and then processing it into an extremely fine wire by wire drawing or wire drawing alone, and then performing intermediate annealing during the wire drawing. Recently, as the trend toward smaller and lighter equipment has become stronger, the outer diameter of the conductor tends to become smaller and smaller, and now ultra-fine wires of α05+am or less are often used. That is, the above-mentioned ultra-fine wires are used as winding wires for microcoils, relays, etc., bonding wires, or ultra-fine cable conductors. Therefore, conductors used for these applications are required to have not only surface quality, ie, wire drawability, but also internal quality, ie, low conductor resistance. For example, when used as a winding wire for a microcoil or the like, it is necessary that the conductor resistance be low in order to further reduce the weight of the coil or to prevent heat generation during use.

[Problem to be solved by the invention 9 As mentioned above, ultra-fine wires, especially ultra-fine wires of 0.05 mm or less, require low conductor resistance in addition to surface quality. When the wire diameter of ultra-fine wire is less than α05m, the conductivity decreases and the conductor resistance increases significantly.
There has been a desire to develop materials with low conductor resistance even in the ultra-fine wire range.

[Means for solving problems]

The present invention has been made in view of the above points, and its purpose is to provide a high-quality ultra-fine wire with low conductor resistance even in the ultra-fine wire region with a wire diameter of 005 m+ or less. That is, the present invention is an ultra-fine wire for electronic devices characterized by being wire-drawn from a unidirectionally solidified oxygen-free copper ingot.

[For production]

The inventors of the present invention investigated various causes of increased conductor resistance when the wire diameter is 0.05 rm or less, and found that conventional ultra-fine wires have problems with their materials and manufacturing methods, and impurities and internal defects significantly increase conductor resistance. It turned out that there was.

First, tough pitch copper, which has been conventionally used as ultra-fine wire for electronic devices, contains 500 to 1,400 ppm of oxygen, and the oxygen is contained in steel as Gum 0 particles, which have a resistivity about 101 times that of copper. However, as the wire diameter becomes smaller, the proportion of Cut 0 particles in the transverse run increases, and therefore the conductor resistance increases.

Second, ingots with a multi-directional solidification structure produced using conventional water-cooled molds suffer from blowholes, shrinkage cavities, etc. during solidification and shrinkage.
As soon as internal defects such as core cracks occur, they remain up to the size of ultra-fine wires, causing an increase in conductor resistance.

Thirdly, in the ultra-fine wire region with a wire diameter of α05m or less, lattice defects, especially grain boundaries, are a major cause of increased conductor resistance, but conventional materials require intermediate annealing during wire drawing. Relatively fine recrystallized grains of about 10-40 μm are usually produced, and the conductor resistance increases due to the grain boundaries of the recrystallized grains.

In view of this, the present inventors have conducted various studies and found that if oxygen-free copper with a reduced amount of oxygen in the steel is used and an ingot with a unidirectionally solidified structure with almost no internal defects is used, ultra-fine wire, especially wire diameter It has been found that the increase in conductor resistance is small even in the ultra-fine wire region where α05yrm or less.

In other words, in a unidirectionally solidified ingot, solidification starts from inside the ingot and grains grow in the longitudinal direction (casting direction), so shrinkage cavities,
Internal defects such as core cracks do not occur, and not only are there no grain boundaries in the longitudinal direction of the ingot, but the processability is good and intermediate annealing is not required, so no recrystallization grain boundaries occur.

As a method for obtaining the unidirectionally solidified ingot, any of the mold heating casting method, moldless rotary pulling casting method, Bridgman method, etc. may be used, but considering the ingot quality, productivity, etc. Most preferred is the hot mold casting method.

Regarding the amount of oxygen in the ultrafine wire of the present invention, it is preferable to limit it to 10 ppm or less, which is a range that does not cause hydrogen embrittlement. Even with copper, the conductor resistance is considerably lower than that of conventional tough pitch copper.

The ultra-fine wire of the present invention has excellent properties such as lower conductor resistance than conventional materials, especially in the ultra-fine wire region with a wire diameter of 0.05 mm or less, but when the wire diameter is larger than 0.05 mm. Even in this case, it has better conductivity than conventional materials.

〔Example〕

Next, examples of the present invention will be described. FIG. 1 is an explanatory diagram of a mold heating continuous casting apparatus used in the present invention. 1 is a casting furnace, 2 is a mold, 5 is a heating device, 4 is a molten metal, 5 is an ingot,
6 is a pinch roll, and 7 is a water cooling device.

The wall of the casting furnace 1 is made of graphite with an inner diameter of 15 mm and an outer diameter of 3 mm.
A mold 2 with a length of 0 m is attached, and the mold 2 is heated to a temperature higher than the melting point of the cast metal by a heating device 5 set around the mold 2, which uses a Kanthal wire as a heating element. The molten metal introduced into the casting furnace 1 enters the mold 2 and is cooled to form an ingot 5, which is pulled out by pinch rolls 6. At this time, since the molten metal 4 in the mold 2 is heated from the surroundings, solidification nucleation does not occur on the inner surface of the mold 2, and the molten metal 4 in the mold 2 is cooled through the ingot 5 by the water cooling device 7 set at the mold outlet. It becomes a directionally solidified tissue.

Next, specific examples of the present invention will be described.

Using the sound of the mold heating continuous casting apparatus, a rod-shaped ingot of oxygen-free copper containing 3 PPm of oxygen and having a single-crystal unidirectional solidification structure and having a diameter of 15 gourds was obtained.

The rod-shaped ingot was heated to a wire diameter of 2.6.0 without intermediate annealing.
The conductivity was measured by cold drawing to each size of 9.0, 25.0.1.0, 05.0, 03, and α02, and the results are shown as solid lines (marked with *) in Figure 2. It was shown in Also, for comparison,
Conventional oxygen-free copper manufactured using a water-cooled mold (oxygen content: 3
ppm) and rough drawn wire with a wire diameter of 81 m hot-groove rolled from an ingot of tough pitch copper were drawn to the above-mentioned sizes and measured for conductive heavy metals.
(x mark) and a broken line (○ mark). In Fig. 2, the horizontal axis shows each size for which the conductivity was measured in the inventive material, comparative material (oxygen-free copper), and conventional material (tough pitch copper), as well as the nSo /s
) f is displayed. Here, SO is the cross-sectional area at a diameter of 15 mm, and S is the cross-sectional area after wire drawing to each size.

As is clear from Figure 2, the conductivity decreases as the wire diameter becomes thinner, but with the present invention material, there is almost no decrease in conductivity when the wire diameter is 0.05 mm or less. It has higher conductivity than tough pitch copper (conventional material) as well as oxygen-free copper (comparative material), and therefore has lower conductor resistance.

Also α9~0. Table 1 shows the results of investigating the influence of sound on conductivity (% engineering AC8) by material and temper for each conductor size of O25 rtm. Here, temper H is processed material, temper A
is an annealed material annealed for 3507: x 30 min for each size.

As is clear from Table 1, the present invention material Nal has a higher resistance to wire than oxygen-free copper No. The diameter is 0.05 tm and the conductivity is LO and 18%, respectively.
This difference has widened further with α025tms. Also, compared to Na5 and Na5 obtained by annealing oxygen-free copper and tough pitch copper produced by conventional methods, o, o5
．． In the following sizes, the present invention material Nα1 has a higher electrical conductivity and therefore a smaller conductor resistance.

〔Effect of the invention〕

The electronic device monthly Mi wire of the present invention is a high-quality ultra-fine wire with low conductor resistance even in the ultra-fine wire region with a wire diameter of α05ma or less, and is suitable for use in automatic cameras, micro coils for watches, etc.
It can be expected to be used in a wide range of applications, such as winding wires for relays, bonding wires, and ultra-fine cable conductors, and has a remarkable industrial effect.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram of a mold heating continuous casting apparatus used in the present invention, and FIG. 2 is an explanatory diagram showing the relationship between wire diameter and electrical conductivity. 1... Casting furnace, 2... Mold, 5... Heating device, 4
... Molten metal, 5 ... Ingot, 6 ... Pinch roll, 7
...Water cooling device.

Claims (3)

[Claims] (1) Ultra-fine wire for electronic devices, characterized by being wire-drawn from a unidirectionally solidified oxygen-free copper ingot. (2) The ultrafine wire for electronic devices according to claim 1, which is drawn from an oxygen-free copper ingot having an oxygen content of 10 ppm or less. (3) The ultrafine wire for electronic devices according to claim 1, wherein the wire diameter is 0.05 mm or less.