JPH0621133Y2 - Low dielectric constant electric wire - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to an electric wire for an electronic device having excellent high-speed transmission characteristics,
In particular, the present invention relates to an improvement in the structure of a low dielectric constant electric wire in which an insulating coating having excellent electrical characteristics is applied to the outer circumference of a three-twisted or four-twisted metal conductor.

[Conventional technology]

A conventional electric wire for this kind of electronic equipment is an insulator having excellent electrical characteristics, particularly a low dielectric constant, as a core for obtaining high-speed signal transmission characteristics or low capacitance, and a single wire with a round cross section or Copper having a concentric twist structure or an insulated wire core having a structure coated on a metal conductor containing copper as a main component is applied.

[Problems to be solved by the device]

The permittivity of a conventional insulating core of this type is determined by the inherent permittivity of the coated insulator. That is, even when, for example, a foamed polyolefin or an insulating material having a low dielectric constant similar thereto is used for the covering insulator, the lower limit of the dielectric constant of the insulating core is about 1.3. Therefore, the signal transmission speed or the capacitance of the coaxial cable using the conventional insulated wire core is limited by the dielectric constant of the used insulated wire core, and the transmission speed is improved and the capacitance is reduced. Is limited.

The present invention realizes high-speed transmission speed and low capacitance, which replaces the conventional insulated core, and further reduces the outer diameter in response to the reduction in diameter, and has a low dielectric constant wire with an insulated core. It is intended to provide.

[Means for Solving the Problems]

In order to achieve the above object, the present invention provides a low-dielectric-constant wire having a low dielectric constant on the outer periphery of an assembly formed by twisting three or four metal conductors having a circular cross-section with a required pitch. From the space between the metal conductor and the insulator formed by stacking the insulator and winding the insulator around the outer periphery of the single-core or multicore metal conductor of five or more cores between the aggregate and the insulator. The present invention is characterized in that it has a large space portion and is constituted by an insulated wire core having a structure in which the outer diameter of the wound and wound insulator is within 5 times the outer diameter of the assembly of twisted metal conductors.

The present invention also includes a low-dielectric-constant electric wire composed of the above-mentioned insulated core alone, or a multi-core low-dielectric-constant electric wire in which a plurality of the above-mentioned insulated cores are assembled.

[Action]

The insulated core according to the present invention has a structure in which three or four round metal conductors having a circular cross-section are twisted together, and an insulator is lapped around the outer periphery of the assembly. A space is formed between the outer circumference of the body and the wrapping of the insulator.

The dielectric constant of the insulating core becomes the equivalent dielectric constant of the entire composite including the portions having different permittivities when the portions having different permittivities exist in the portion excluding the conductor portion made of metal. Therefore, when the dielectric constants of the insulators are the same, the equivalent dielectric constant can be reduced as the portion of air having a relative dielectric constant close to 1 increases.

The metal conductor of the present invention, in which three or four round strands are twisted together, is compared with the case of using a normal single wire or a metal conductor of a multi-core concentric twist structure such as seven or nineteen wires. By forming a larger space between the aggregate of metal conductors and the lap winding of the insulator, the equivalent dielectric constant of the entire insulated core can be reduced.

The effect of the low-dielectric-constant wire according to the structure of the present invention depends on the size of the space existing between the assembly of metal conductors having excellent electrical characteristics and the insulator wound around the metal conductor. In the case of an assembly of metal conductors with different diameters, the effect becomes smaller as the diameter of the insulating core increases, that is, as the insulating core becomes thicker, the effect becomes smaller. The diameter is preferably within 5 times the outer diameter of the aggregate of metal conductors, and when it exceeds 5 times, almost no effect is recognized. Embodiments will be described below with reference to the drawings.

〔Example〕

1A and 1B are views showing a cross-sectional structure of a low dielectric constant electric wire embodiment of the present invention. FIG. 1a shows a structure in which three metal conductors 1 each made of a round wire having a circular cross section are twisted with a required pitch, and an insulator 2 made of, for example, a low dielectric constant plastic tape is wound around the outer circumference. It is an insulated wire core. Here, the outer diameter B of the insulated wire core is formed within 5 times the outer diameter A of the assembly after the metal conductors 1 are twisted together.

FIG. 1b is an example in which four metal conductors 1 are twisted together,
As in FIG. 1a, the outer diameter B of the insulated core is formed within 5 times the outer diameter A of the assembly in which the metal conductors 1 are twisted together.

One of the features of this embodiment, whose sectional structure is shown in FIGS. 1a and 1b, is that the structure in which three or four metal conductors 1 are housed makes it possible to obtain five or more, for example, seven in general. Alternatively, the space 3 formed between the metal conductor 1 and the insulator 2 is made larger than an electric wire in which 19 metal conductors 1 are twisted and assembled.

FIG. 2 is a diagram showing a structural outline of an embodiment of a coaxial cable to which the low dielectric constant electric wire of the present invention is applied. The coaxial cable of the present embodiment is an example using the insulated wire core containing three metal conductors shown in FIG. 1a.

Metal conductor 4 using annealed copper wire with an outer diameter of 0.2 mm
75 μ thick on the outer circumference of the assembly consisting of 3 twisted and assembled
m of a porous stretched fluororesin tape is overwound to form an insulating wire core having an outer diameter of about 0.8 mm, and an aluminum-bonded polyester tape having a thickness of 15 μm is provided on the outer circumference of the insulating wire core. It is a coaxial cable in which a shield layer 6 is provided by being wound in layers and an outer cover 7 is extrusion-coated on the outer layer.

For the coaxial cable using the low dielectric constant electric wire of this example, the propagation delay time directly correlated with the dielectric constant was measured, and a result of 3.5 n sec / m was obtained.

A coaxial cable of the comparative example, which has the same structure as that of the present embodiment and uses an insulated wire core containing a single-core conductor and a concentric-stranded conductor instead of the three-strand assembly of the metal conductor 4, and a shield layer and a jacket. Similarly, when the propagation delay time was measured, the best result was 3.7 n sec / m.

That is, it is confirmed that the coaxial cable using the insulated core of the structure of the present invention can improve the transmission speed by about 6% as compared with the coaxial cable using the insulated core of the normal comparative example structure. did.

Also, as a result of measuring the capacitance, the coaxial cable using the insulated wire core according to the present invention is about 10% as compared with the conventional coaxial cable using the insulated wire core having a structure containing a single-core or concentric twisted conductor. It was a low value, and the characteristics of lower capacitance were obtained with the same size. That is, it is confirmed that the permittivity of the coaxial cable according to the present invention is 10% lower than that of the coaxial cable using the insulated core of the conventional structure in the structure formed of the same insulating material and having the same size. It was

[Effect of the Invention] As described above, the low dielectric constant electric wire of the present invention has excellent electrical characteristics in a metal conductor assembly in which three or four metal conductors of round element wires are twisted with a required pitch. In addition, it is possible to realize an insulated wire with a low dielectric constant because it is composed of an insulated wire core that has a structure in which a tape-shaped insulator with a low dielectric constant is wound. The outer diameter is smaller than that of the insulated wire with the conventional structure that has the same capacity and the reduction of the capacity, which is also effective for thinning.

Therefore, the low-dielectric-constant wire of the present invention is particularly effective when applied to electronic equipment that requires high-speed transmission and acoustic equipment that takes advantage of low capacitance. Will also contribute.

[Brief description of drawings]

1A and 1B are sectional structural views of a low dielectric constant electric wire embodiment of the present invention, and FIG. 2 is a structural schematic view of a coaxial cable embodiment to which the low dielectric constant electric wire of the present invention is applied. 1 ... Metal conductor, 2, 5 ... Insulator, 3 ... Space part, 4
…… Metal conductor, 5 …… Insulator, 6 …… Shield layer, 7…
… Outer coat

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Creator Akinori Mori 3-3 Satsuki-cho, Kanuma City, Tochigi Sumitomo Electric Industries, Ltd. Kanto Works (72) Creator Kozo Kamikido 5-33-1, Shiba, Minato-ku, Tokyo No. Within NEC Corporation (72) Inventor Noriaki Nishiyama 5-33-1 Shiba, Minato-ku, Tokyo Inside NEC Corporation (72) Mitsuo Takamoto 5-33-1 Shiba, Minato-ku, Tokyo Within NEC Corporation (56) References JP-A-56-126207 (JP, A) JP-A-62-71822 (JP, U)

Claims (3)

[Scope of utility model registration request] 1. A low dielectric constant insulator (2) is wound around an outer periphery of an assembly obtained by twisting three or four metal conductors (1) having a circular cross-section with a required pitch, A space that is larger than the space between the metal conductor and the insulator, which is formed by stacking the insulator around the outer periphery of a single-core or multicore metal conductor of five or more cores between the insulator and the insulator (3) From an insulated core having a structure in which the outer diameter (B) of the insulating body (2) wound in a stack is within 5 times the outer diameter (A) of the assembly in which the metal conductors (1) are twisted together. A low dielectric constant electric wire characterized by 2. A low-dielectric-constant electric wire comprising a single insulated wire core according to claim 1. 3. A multicore low-dielectric-constant electric wire obtained by collecting the insulated wire core according to claim 1.