JP2003132745A - Coaxial cable improved of flexibility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coaxial cable wherein flexibility/twisting property is improved thereby there is not anxiety that the high frequency property is damaged. SOLUTION: This is the coaxial cable in which the flexibility is improved wherein at the circumference of the inner conductor 1 of silver containing copper alloy element wire, preferably at the circumference of an insulator 2 installed on the stranded wire of the silver containing copper alloy element wire, the outer conductor 3 composed of the silver containing copper alloy element wire, preferably composed of its metal braid or multi-layered structure is arranged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coaxial cable used for a hinge portion of an electronic device such as a mobile phone and a notebook computer. More specifically, the present invention relates to a coaxial cable that has improved flexibility and twistability, and thus does not impair the high frequency characteristics inherent to the cable.

[0002]

2. Description of the Related Art Conventionally, in a coaxial cable used for a hinge portion of a mobile phone, a notebook computer or the like, a material of an inner conductor or an outer conductor is a copper wire. However, the copper wire is vulnerable to stress such as repeated bending or twisting, and has a drawback that the cable is easily broken or broken. Therefore, by increasing the thickness of the insulator and the jacket, the load on the conductor or copper wire can be reduced, or in parallel with this, the ETFE having high mechanical strength can be used as a material for the insulator and the jacket. (Ethylene-tetrafluoride copolymer resin) was adopted. However, even with the above solution, new problems still occur. In other words, by increasing the thickness of the insulator and jacket, the finished diameter of the coaxial cable becomes thicker, and as a result, it becomes difficult to attach connectors and terminals, which have been done so far, and processing time increases. There's a problem. In addition, although the flexibility of the coaxial cable is slightly improved by using ETFE, it is inferior in heat resistance to PFA (tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin), which was another option. When soldering to the inner and outer conductors is required at the time of terminal processing, the resin is melted and deformed, and problems such as poor pressure resistance occur at the terminal section after processing.

[0003]

SUMMARY OF THE INVENTION The present invention solves the problems of the prior art and provides a coaxial cable in which the flexibility and twistability are improved and there is no fear of impairing the high frequency characteristics. It is in.

[0004]

Means for Solving the Problems As a result of repeated studies to solve the above problems, the present inventors have arranged an inner conductor and an outer conductor of a coaxial cable, particularly an outer conductor of a material having a high tensile strength. It was found that the flexibility and the twisting property can be improved without increasing the outer diameter of the cable. Thus, according to the present invention, there is provided a coaxial cable with improved flexibility, characterized in that an outer conductor made of a silver-containing copper alloy wire is arranged on the outer periphery of an insulator provided on the inner conductor. .

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, FIG. 1 shows a sectional view of a coaxial cable of the present invention. In this example, the inner conductor 1
The outer conductor 3 made of, for example, a metal braid layer is provided as a single layer on the outer periphery of the insulator 2 provided above. Here, a twisted wire of an alloy element wire is generally used as the inner conductor. As the alloy wire, a type containing tin or silver is used, and the content of tin or silver is preferably 1 to 15%. Further, these alloy wires may be plated with tin or silver. This alloy wire is used not only in the form of a single wire but also in the form of a stranded wire, but the latter is more preferred from the viewpoint of improving the flexibility intended by the present invention. The final inner conductor size is 40-20, preferably 36-30, in AWG notation. When the inner conductor size is thicker than 20 with AWG, the finished outer diameter of the coaxial cable becomes thicker,
It becomes difficult to crawl inside the equipment, while on the other hand, if the inner conductor size is smaller than 40 in AWG, it becomes difficult to process the end. The insulator is not particularly limited as long as it has an insulating function, but in consideration of the high frequency characteristics required for coaxial cables and the thinning of the finished outer diameter, fluororesins such as ETFE and PFA are considered. Is preferred and most preferably it is applied in extrusion coated form. The thickness of this insulator is preferably in the range of 0.05 to 1.0 mm, but when the characteristic impedance is included as a required characteristic, the thickness of the insulator is determined by the size of the inner conductor. Next, the outer conductor 3 will be described. A feature of the present invention is that a silver-containing copper alloy element wire is adopted as a material of the outer conductor. In this case, the silver content is preferably in the range of 1 to 15%. Further, it is preferable that the thickness of the alloy element wire is in the range of 28 to 49 in AWG display, and 7 to 19 pieces of the element wire are bundled and arranged as a stranded wire. This strand may be plated with tin, silver or the like. And, as the structure of the outer conductor, a metal braid is preferably adopted, and the number of braids at that time is 8 to 24, and the number of possessions is 3
~ 8 are preferred.

Next, FIG. 2 is a sectional view showing another embodiment of the coaxial cable of the present invention. In this example, a metal braid layer 3a and an outer conductor having a so-called two-layer structure in which a metal braid layer 3b is further surrounded by the metal braid layer 3a are arranged on the outer periphery of the insulator 2 provided on the inner conductor 1. In this case, since the metal braid layer has a multi-layer structure, the shield characteristics of the coaxial cable are improved as compared with the single-layer structure shown in FIG.

1 and 2, most preferably, the inner conductor 1 is a stranded wire of silver-containing copper alloy wire, and the outer conductor 3 is a silver-containing copper alloy wire. This is the case adopted. Further, it goes without saying that the outer periphery of the outer conductor may be provided with a protective coating layer 4 which is commonly used in the art, if necessary.

[0008]

EXAMPLES Examples and comparative examples below show examples of coaxial cables designed with a mandrel diameter R = 2. [Example 1] As the inner conductor 1, seven concentric twisted silver-plated tin-containing copper alloy wires having a wire diameter of 0.05 mm,
An outer diameter of 0.15 mm was used. On the outer circumference of the inner conductor 1, PFA) was extruded as an insulating layer 2 to a thickness of 0.15 mm. Next, a wire diameter of 0.0
Number of strokes of a 5 mm tin-plated silver-containing copper alloy wire 8
A coaxial cable having an outer diameter of 0.70 mm was obtained by surrounding it with the outer conductor 3 having the braided structure. Further, as the protective coating layer 4, PFA having excellent heat resistance and solder resistance was extruded to a thickness of 0.09 mm on the outer periphery of the outer conductor 3 to obtain a final product having an outer diameter of 0.88 mm. When this product was subjected to the bending test (Fig. 3) described below, the bending number was 3
It was confirmed that the flexibility was remarkably improved by the time the wire was broken for the first time after 22,000 cycles. [Bending Test Method] Using a bending tester as shown in FIG. 3, a coaxial cable is held by a fixed portion, and a constant load (here, 100 g) is applied to the cable. Next, a mandrel is applied to the cable under load, and 180 ° on one side is repeatedly bent using the mandrel as a fulcrum. The evaluation is judged by the disconnection status of the inner and outer conductors.

[Example 2] As the inner conductor 1, 0.05 m
An outer diameter of 0.15 mm formed by concentrically twisting seven silver-plated silver-containing copper compound wires having an element wire diameter of m was used. PFA with a thickness of 0.15 is formed as an insulating layer 2 on the outer periphery of the inner conductor 1.
extruded to mm. Next, on the outer periphery of the insulating layer 2, a tin-plated silver-containing copper alloy wire having a wire diameter of 0.05 mm is struck 8,
Surrounded by an outer conductor 3 composed of a braided structure of 6
The coaxial cable has an outer diameter of 0.70 mm. Further, as the protective coating layer 4, PFA having excellent heat resistance and solder resistance was extruded to a thickness of 0.09 mm on the outer periphery of the outer conductor 3 to obtain a final product having an outer diameter of 0.88 mm. About this product
When the same bending test was performed, it was confirmed that the breaking property was remarkably improved by the time when the breaking occurred for the first time after the number of bending was 40,000 times.

[Comparative Example 1] As the inner conductor 1, 0.05 m
An outer diameter of 0.15 mm formed by concentrically twisting seven silver-plated annealed copper wires having an element diameter of m was used. This inner conductor 1
PFA as an insulating layer 2 is formed on the outer circumference of 0.15 mm thick.
Extruded into. Next, the outer circumference of the insulating layer 2 is covered with a wire diameter of 0.
A tin-plated annealed copper wire of 05 mm is wound around an outer conductor 3 formed of a braided structure having a striking number of 8 and a holding number of 6, and an outer diameter of 0.
It was a 70 mm coaxial cable. Furthermore, the protective coating layer 4
As a heat resistance and a solder resistance PF on the outer periphery of the outer conductor 3,
A was extruded with a thickness of 0.09 mm to obtain a final product having an outer diameter of 0.88 m. When this product was subjected to the same bending test, disconnection occurred after only 4000 times of bending.

[Comparative Example 2] As the inner conductor 1, 0.05 m
An outer diameter of 0.15 mm was obtained by concentrically twisting seven silver-plated tin-containing copper alloy wires having a diameter of m. PFA as an insulating layer 2 was extruded to a thickness of 0.15 mm on the outer periphery of the inner conductor 1. Next, an outer conductor composed of a braided structure having a striking number of 8 and a staggering number of 6 is formed on the outer circumference of the insulating layer 2 by a tin-plated tin-containing copper alloy strand having a strand diameter of 0.05 mm
A coaxial cable having an outer diameter of 0.70 mm was wound around with 3. Further, as the protective coating layer 4, heat-resistant and solder-resistant PFA having a thickness of 0.09 mm is extruded on the outer periphery of the outer conductor 3 to obtain a final product having an outer diameter of 0.88 mm. When this product was subjected to the same bending test, disconnection occurred after only 6,000 times of bending.

[0012]

According to the present invention, the flexibility and the twisting property are remarkably improved, and as a result, there is no fear that the original high frequency characteristics of the coaxial cable are impaired, so that high-speed signal transmission is ensured.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a coaxial cable according to the present invention.

FIG. 2 is a cross-sectional view showing another example of the coaxial cable according to the present invention.

FIG. 3 is a front view illustrating a bending test method of a coaxial cable.

[Explanation of symbols]

1 inner conductor 2 insulator 3 outer conductor 4 Protective coating layer

Claims (5)

[Claims] 1. A coaxial cable with improved flexibility, characterized in that an outer conductor made of a copper alloy wire containing silver is arranged on the outer periphery of an insulator provided on the inner conductor. 2. The coaxial cable with improved flexibility according to claim 1, wherein said inner conductor is a stranded wire of a silver-containing copper alloy element wire. 3. The coaxial cable with improved flexibility according to claim 1, wherein the structure of the outer conductor is a metal braid. 4. The coaxial cable according to claim 1, wherein the outer conductor has a multilayer structure. 5. The content of silver in the copper alloy wire containing silver is 1
The coaxial cable with improved flexibility according to any one of claims 1 to 4, wherein the coaxial cable is in the range of -15 wt%.