KR20140001728A - Insulated wire, coaxial cable and multiconductor cable - Google Patents

Abstract

Provided are an insulated wire, a coaxial cable, and a multi-core cable which can reduce the dielectric constant of the insulator and reduce the dielectric constant of the insulator and obtain good electrical characteristics with a narrow diameter. The coaxial cable 11 covers the center conductor with an insulator having a gap portion 14 continuous in the longitudinal direction, and arranges the outer conductor 15 on the outer circumference of the insulator 13, and the gap portion 14 has a circular cross section. Or formed in an ellipse shape, and 6 to 8 voids 14 are equally disposed on the insulator 13, and the area of all voids 14 in a cross section perpendicular to the longitudinal direction of the coaxial cable 11. When the ratio of the area of the void portion 14 to the sum of the areas of the insulator 13 and the void ratio was set as the void ratio, the void ratio in which all the void portions 14 were combined was set to 18% or more and 35% or less.

Description

Insulated Wire, Coaxial Cable, and Multi-Conductor Cables {INSULATED WIRE, COAXIAL CABLE AND MULTICONDUCTOR CABLE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to insulated wires, coaxial cables, and multi-core cables for use in telecommunications, information equipment, industrial machinery, and wiring of vehicles.

Insulated wires and coaxial cables are used for wiring in devices, between devices, in machines, and in vehicles. Insulated wire is a core conductor covered with an insulator, and coaxial cable is usually a structure in which the center conductor is covered with an insulator, the outer circumference of the insulator is covered with an outer conductor, and the outside thereof is covered with a protective sheath. And a few mm. These wires and the like are required to make the dielectric constant of the insulator covering the outer circumference of the center conductor as small as possible in order to obtain good electrical characteristics with a narrow diameter.

For this reason, a coaxial cable is known which has a low dielectric constant by covering the center conductor with an insulator having six to nine cross-sectional circular or elliptic voids extending in the longitudinal direction, and placing an outer conductor on the outer circumference of the insulator (for example, See Patent Document 1). Moreover, the coaxial cable which fan-shaped the cross-sectional shape of a space part is also known (for example, refer patent document 2).

International Publication No. 2010/035762 Japanese Patent Publication No. 2009-110975

As described above, when the voids are formed in the insulator, the dielectric constant of the insulator can be made small and good electrical characteristics can be obtained.

However, if the porosity of the gap portion is too large, the breakdown voltage between the center conductor and the outer conductor decreases. In addition, when the porosity is large, the strength may be reduced. In particular, when the cross section of the air gap is fan-shaped, the air gap may be easily deformed due to warpage, and the cable may collapse due to external pressure, making it difficult to secure stability of transmission characteristics. .

An object of the present invention is to provide an insulated wire, a coaxial cable, and a multi-core cable which can reduce the dielectric constant of an insulator without causing a decrease in breakdown voltage and a decrease in strength, and can obtain good electrical characteristics with a narrow diameter.

The insulated wire of this invention which can solve the said subject is an insulated wire which covered the center conductor with the insulator which has a space part continuous in a longitudinal direction,

The voids are circular or elliptical in cross section, and six to eight of the voids are equally disposed on the insulator, and in the cross section perpendicular to the cable longitudinal direction, the sum of the area of all the voids and the area of the insulator. When the ratio of the area of the voids is set to the void ratio, the void ratio combined all the voids is set to 18% or more and 35% or less.

The coaxial cable of this invention is a coaxial cable which covered the center conductor with the insulator which has a space part continuous in a longitudinal direction, and arrange | positioned the outer conductor in the outer periphery of the said insulator,

The voids are circular or elliptical in cross section, and six to eight of the voids are equally disposed on the insulator, and in the cross section perpendicular to the cable longitudinal direction, the sum of the area of all the voids and the area of the insulator. When the ratio of the area of the voids is set to the void ratio, the void ratio combined all the voids is set to 18% or more and 35% or less.

In the insulated wire or coaxial cable of this invention, it is preferable that the said insulator is formed from the tetrafluoroethylene perfluoro alkyl vinyl ether copolymer.

The multicore cable of the present invention is characterized by containing a plurality of the above insulated wires or coaxial cables.

According to the present invention, since six to eight void portions having a circular cross section or an ellipse shape are evenly disposed on the insulator, the dielectric constant of the insulator can be made small and good electrical properties can be obtained at a narrow diameter. In addition, by setting the porosity to 18% or more and 35% or less, the withstand voltage between the center conductor and the outer conductor can be reliably ensured without causing a decrease in strength.

1 is a cross-sectional view of a coaxial cable showing one embodiment of the present invention;
2 is a partial perspective view of an extruder used when producing a coaxial cable according to the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, the example of embodiment of the coaxial cable and multicore cable which concerns on this invention is described with reference to drawings.

As shown in FIG. 1, the coaxial cable 11 which concerns on this embodiment covers the center conductor 12 with the insulator 13, arrange | positions the outer conductor 15 in the outer periphery of the insulator 13, and puts the outer side. It is a structure covered with the outer cover (16). The center conductor 12 and the part of the insulator 13 of the coaxial cable 11 are the same structures also in the insulated wire of this invention.

The insulator 13 has eight space | gap parts 14 continuous in a longitudinal direction. These space | gap part 14 is formed in circular cross section of the outer diameter D3, and is arrange | positioned equally to the insulator 13 in the circumferential direction. In addition, the center conductor 12, the insulator 13, and the outer conductor 15 and the insulator 13 are in close contact with each other.

The center conductor 12 is formed by the single wire or stranded wire which consists of a silver plating or tin plating differential line or copper alloy wire. In the case of a stranded wire, for example, the outer diameter D2 of the single conductor having a diameter of 0.030 mm is 0.090 mm (the equivalent of American Wire Gauge # 40), or the outer diameter of the single conductor having a diameter of 0.025 mm is 7 It is used that (D2) is 0.075 mm (equivalent to AWG # 42).

As the insulator 13, a fluororesin made of PFA (tetrafluoroethylene perfluoroalkyl vinyl ether copolymer) is used, and the insulator 13 is formed by extrusion molding the fluororesin. Since PFA has a low dielectric constant among dielectric resins (a relative dielectric constant of about 2.1 at about 1 MHz), the insulator can be made thinner with the same capacitance as compared with the case where other resins are used.

The outer diameter D1 of the insulator 13 is about 0.2 mm, and the capacitance is comparatively high, 90 pF / m-120 pF / m.

The outer conductor 15 is formed of a bare copper wire (interconnected copper wire or copper alloy wire) or a silver-plated or tin-plated copper wire or copper alloy wire of the same thickness as the small conductor used for the center conductor 12. It is formed by arranging the transverse or braided structure on the outer periphery. Moreover, in order to improve a shield function, you may make it the structure which a metal foil tape is provided in parallel in the layer just outside of the outer conductor 15. As shown in FIG.

The outer shell 16 is formed by extrusion molding resin materials, such as a fluororesin, or winding resin tapes, such as a polyester tape.

The outer diameter of the coaxial cable 11, which is the outer diameter of the outer shell 16, is about 0.31 mm.

The coaxial cable 11 is used for, for example, antenna wiring in a mobile phone or a notebook computer, wiring for connecting a liquid crystal display (LCD) and a central processing unit (CPU), or used as a multi-core cable for connecting a sensor and a device. In many cases, miniaturization and thinning of these terminal devices require thinning of coaxial cables and thinning of multicore cables.

The coaxial cable 11 needs to have a predetermined impedance (50? For this purpose, it is necessary to reduce the dielectric constant of the insulating layer between the center conductor 12 and the outer conductor 15. In this embodiment, by providing the space | gap part 14 in the insulator 13, the dielectric constant of the insulator 13 is made small and the coaxial cable 11 can obtain favorable electrical characteristics with a narrow diameter. .

However, if the porosity of the gap portion 14 is too large, there is a fear that the withstand voltage between the center conductor 12 and the outer conductor 15 is lowered. In addition, since the thickness of the insulator 13 is thin due to its narrow diameter, it may cause a decrease in strength, which may make it impossible to withstand the external pressure and the bending applied to the cable.

For this reason, in this embodiment, when the ratio of the space | gap part 14 with respect to the sum of the area of all the space | gap parts 14 and the area | region of the insulator 13 is made into the porosity, the resonance which combined all the space | gap parts 14 summed up. By setting the ratio to 18% or more and 35% or less, the withstand voltage between the center conductor 12 and the outer conductor 15 is reliably ensured without causing a drop in strength. In addition, since the eight void portions 14 formed in a circular cross section are equally disposed on the insulator 13 made of PFA, high strength can be maintained while miniaturization and low dielectric constant of the insulator 13 are achieved.

This makes it possible to thicken the center conductor 12 by reducing the thickness of the insulator 13 in the case of setting a predetermined capacitance (for example, 100 pF / m) at the same outer diameter, thereby reducing the conductor resistance. This can improve the transmission efficiency. For example, even in AWG # 42, the center conductor 12 of AWG # 40 can be used.

If the outer diameter of the center conductor 12 is the same, the outer diameter of the coaxial cable 11 can be made small by making the thickness of the insulator 13 thin.

Even if it is an insulated wire which does not have the external conductor 15, the same effect as the said coaxial cable 11 can be enjoyed by making the insulator 13 into the said structure.

In the coaxial cable 11 of the above embodiment, eight void portions 14 are formed in the insulator 13, but the number of the void portions 14 is not limited to eight but may be six or seven. In addition, in the said embodiment, although the case where the space | gap part 14 of circular cross section was formed was illustrated, the space | gap part 14 may be elliptical shape in cross section. The same applies to insulated wires.

In addition, although the coaxial cable 11 was demonstrated as an example of a single-core wire, you may make it the multi-core cable which bundled this coaxial cable 11 or an insulated wire. This multi-core cable may include only a coaxial cable, may include only an insulated wire, or may include both. Moreover, it is good also as a multi-core coaxial cable which shielded the coaxial cable or the insulated wire by the common shield conductor.

As shown in FIG. 2, the coaxial cable 11 or the insulated wire can be manufactured using the extruder 30 in which the die 31 and the point 41 are combined.

The point 41 is provided with a cylindrical member 45 having an outer shape by the number of the gaps 14, and is combined with the die 31 having a circular outlet 33 to form the point 41 and the die 31. The resin is extruded from between (Euro 51 and 52). The center conductor 12 is taken out from the center hole 44 of the cylindrical part 43 of the point 41. FIG. The extruded resin is coated on the center conductor 12. The resin may be coated by an in-lacing method in which the resin exiting the exit of the die 31 is extended to decrease the diameter to coat the resin. Resin does not flow in the cylindrical member 45, and this part becomes the space | gap part 14. As shown in FIG. When the vent hole 46 is provided in this member 45, the space | gap part 14 which resin does not flow in the resin extruded from the die 31 is ensured, and the cross section becomes circular or elliptical.

In the extruder 30, the porosity of the insulator 13 can be easily adjusted to the diameter of the cylindrical member 45 provided at the point 41. The lower the porosity is, the higher the porosity is, the higher the degree of freedom of the combination of the die 31 and the point 41 and the drop-off rate.

Example

In order to evaluate the above-mentioned coaxial cable by this invention, the Example product of this invention and the comparative example were produced and tested. The test articles of Examples 1, 2 and Comparative Example 1 used a stranded wire having an outer diameter of 0.09 mm braided with seven tin-plated copper alloy wires having an outer diameter of 0.03 mm for the center conductor, and extruded and coated with fluororesin (PFA) thereon. It was set as the insulator of 0.20 mm of outer diameters. When extruding the insulator, the cylindrical members 45 forming the void portions as shown in FIG. 2 were used to uniformly form the eight cross-sectional circular void portions extending in the longitudinal direction in the insulator. The outer conductor transversely wound a tin-plated interlocking wire having an outer diameter of 0.03 mm, and formed an outer sheath made of polyester tape thereon to form a coaxial cable of AWG # 40 having an outer diameter of 0.31 mm. The total porosity of the voids in the insulator is 18% (capacitance 110pF / m) in Example 1, 35% (capacitance 100pF / m) in Example 2, 40% (capacitance 95pF / m) in Comparative Example 1 )

Moreover, as the comparative example 2, the coaxial cable without a void part (porosity 0%) was produced. In this Comparative Example 2, a silver-plated copper alloy wire having an outer diameter of 0.025 mm was twisted with a stranded wire having an outer diameter of 0.075 mm, and fluorine resin (PFA) was extruded to form an insulator having an outer diameter of 0.20 mm. The outer conductor transversely wound a tin-plated interlocking wire having an outer diameter of 0.03 mm, and formed an outer sheath made of polyester tape thereon to form a coaxial cable of AWG # 42 having an outer diameter of 0.31 mm. The capacitance was 110 pF / m.

The following test was performed 3 times about the coaxial cable of each said test piece, and each coaxial cable was evaluated.

(1) withstand voltage test

The voltage of alternating current was applied between the center conductor and the outer conductor, and the voltage value when the insulator was broken and the short between the center conductor and the outer conductor was measured.

(2) dynamic cut-through

It presses with a round blade from the outer shell of a coaxial cable and collapses, and the load when the center conductor and an outer conductor are short-circuited is measured. In addition, the round blade made the material SUS and made the tip diameter r 1 mm.

The results of the test are shown in Table 1. In addition, the numerical value of Table 1 is an average value of the test result of three times.

Example  One Example  2 Comparative Example  One Comparative Example  2 Dielectric breakdown voltage
(㎸) 5.6 4.4 2.5 4.7 Dynamic cut through
(N) 27.7 25.2 19.3 25.3 evaluation O O X O

In the coaxial cable of Example 1 whose porosity of the space | gap part was 18%, withstand voltage was 5.6 kV as an average value and the load of dynamic cut through was 27.7 N as an average value. Thus, in the coaxial cable of Example 1, it was recognized that it had sufficient withstand voltage and strength, and the evaluation of reliability was good ((circle)).

In the coaxial cable of Example 2 whose porosity of the space | gap part was 35%, withstand voltage was 4.4 kV as an average value, and the load of dynamic cut through was 25.2 N as an average value. Thus, it was recognized that the coaxial cable of Example 2 had sufficient withstand voltage and strength, and the evaluation of reliability was good (○).

In the coaxial cable of Comparative Example 1 having a porosity of 40% of the voids, the average voltage was 2.5 kV as an average value and the load of the dynamic cut through was 19.3 N as an average value. Thus, in this coaxial cable of the comparative example 1, it was recognized that there was insufficient in both a breakdown voltage and strength, and the evaluation of reliability was bad (x).

The coaxial cable of Comparative Example 2 in which the porosity of the void portion is 0% has the same capacitance as that of Example 1. The load of the breakdown voltage and the dynamic cut through is also the same as in Example 1. However, the coaxial cable of this comparative example 2 has a one-small size of AWG in the center conductor, and is inferior to the coaxial cable of Example 1 in terms of allowable current and conductor resistance.

In addition, when a coaxial cable having no gaps is fabricated using a center conductor having the same dimensions as in Example 1, the outer diameter thereof is 0.34 mm, and the outer diameter thereof is increased by about 1, which does not satisfy the requirement of thinning.

In the above example, the coaxial cable of AWG # 40 was evaluated. However, when the withstand voltage test and the dynamic cut-through test were performed on the coaxial cable having a small diameter (AWG # 42), the porosity of the entire air gap was 18% and 35%. In the case of, evaluation was favorable.

Although this invention was detailed also demonstrated with reference to the specific embodiment, it is clear for those skilled in the art that various changes and correction can be added without deviating from the mind and range of this invention. This application is based on the JP Patent application 2010-268036 of an application on December 1, 2010, The content is taken in here as a reference.

11 coaxial cable 12 center conductor
13 insulator 14 air gap
15: outer conductor

Claims (5)

Insulated electric wire which covered the center conductor with the insulator which has a space part continuous in a longitudinal direction,
The voids are circular or elliptical in cross section, and six to eight of the voids are equally disposed on the insulator, and the sum of the area of all voids and the area of the insulator in the cross section perpendicular to the longitudinal direction of the cable. When the ratio of the area of the voids to the voids is set to the void ratio, the void ratio of all the voids is set to 18% or more and 35% or less.
Insulated wires. The method of claim 1, wherein
The insulator is formed of a tetrafluoroethylene perfluoroalkyl vinyl ether copolymer, characterized in that
Insulated wires. In the coaxial cable which covered the center conductor with the insulator which has a space part continuous in a longitudinal direction, and arrange | positioned the outer conductor in the outer periphery of the said insulator,
The voids are circular or elliptical in cross section, and six to eight of the voids are equally disposed on the insulator, and in the cross section perpendicular to the cable longitudinal direction, the sum of the area of all the voids and the area of the insulator. When making the ratio of the area of a space part into void ratio, the void ratio which combined all the void parts was made into 18% or more and 35% or less, It is characterized by the above-mentioned.
Air gap cable. The method of claim 3, wherein
The insulator is formed of a tetrafluoroethylene perfluoroalkyl vinyl ether copolymer, characterized in that
coax. The insulated wire of Claim 1 or 2 or the coaxial cable of Claim 3 or 4 are accommodated, It is characterized by the above-mentioned.
Multi-core cable.

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