JP2002216545A - Rounded flat cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rounded flat cable such that the appearance of the final product is good because of a good appearance of a flat cable as an intermediate product with high dimensional accuracy as well as extremely high impedance between insulated wire cores. SOLUTION: A parallel-arranged insulated and twisted wire is formed by arranging a plurality of twisted insulated wires formed by twisting insulated wire cores in parallel. A thermally welded portions where contact surfaces of the neighboring twisted insulated wires are thermally welded in the longitudinal direction of the parallel-arranged twisted insulated wire and non-welded portions that are not thermally welded are alternately repeated for a predetermined distance in order to comprise a welded portion/non-welded portion alternately-repeating flat cable. A round flat cable is made by providing a sheath layer on a periphery of a rounded flat cable formed by turning the welded portion/non-weld portion alternately-repeating flat cable to the round shape. In the rounded flat cable, the insulated wire cores comprise a conductor having coated thereon a thermoplastic olefin resin having a dielectric constant of 2.3 or less measured according to ASTM-D-1531.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a round flat cable.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for smaller, higher performance, higher density mounting, lighter weight, lower cost electronic devices, and the like.

[0003] Accordingly, insulated wires and cables used for wiring of these electronic devices are required to have higher performance, higher density mounting, terminal processing, erroneous wiring prevention, connector connection workability, etc. than ever before. It is becoming.

A flat cable is known as a cable for electronic equipment which is excellent in high-density mounting, terminal processing, miswiring prevention, connector connection workability, and the like. In particular, round flat cables formed by rounding flat cables have been frequently used.

[0005] In general, the manufacturing procedure of this kind of round flat cable is as follows.

First, a plurality of insulated wires serving as insulated wire cores are prepared.

Next, two insulated wires are sequentially taken out of the prepared plurality of insulated wires, and they are twisted to form a twisted insulated wire pair.

Next, a plurality of the insulated wire pairs are obtained by arranging a plurality of the insulated wire pairs in parallel.

[0009] Next, the contact surfaces of the adjacent insulated wire pairs which are adjacent to each other along the longitudinal direction of the insulated wire pairs are arranged so as not to be heat-sealed. A flat cable is manufactured by alternately repeating a fused portion at a predetermined interval so as to alternately repeat a fused portion and a non-fused portion.

Finally, the flat cable obtained by alternately repeating the fused portion and the non-fused portion thus obtained is formed into a round shape, and a sheath layer is extruded and coated on the outer periphery to obtain a round flat cable. (Note that as a prior document of this type of round flat cable, for example,
No. 35322, Japanese Utility Model Publication No. 61-109012,
JP-A-61-123413, JP-A-63-170
No. 12 publication. As a conventional insulated wire serving as an insulated wire core, a vinyl chloride resin insulated wire formed by coating a conductor with a vinyl chloride resin admixture has been used.

On the other hand, recently, as a cable for electronic equipment, a round flat cable capable of matching the characteristic impedance between insulated wires to a high impedance has been required due to the problem of improving the signal speed. .

However, in the case of a round flat cable using a vinyl chloride resin insulated wire as the insulated wire core, it is difficult to match a high impedance between the insulated wire cores.

As the round flat cable which can match the impedance between the insulated wires with high impedance, a round flat cable using a foamed polyethylene insulated wire as the insulated wire is desirable.

[0014]

However, when manufacturing a round flat cable using a foamed polyethylene insulated wire as the insulated wire core, it is extremely difficult to manufacture a flat cable as an intermediate product thereof.

[0015] That is, since foamed polyethylene essentially contains air bubbles, there is a problem that heat deformability is large. For this reason, in the foamed polyethylene insulated wire formed by covering the conductor with the foamed polyethylene, the foamed polyethylene insulating layer has a large thermal deformation property. For this reason, when the foamed polyethylene insulated wire pair twisted body is arranged in parallel, and then the longitudinal direction is intermittently interposed, the foamed polyethylene insulated wire contact surfaces of the adjacent insulated wire cores are heat-fused to form a flat cable.
The foamed polyethylene insulating layer of the foamed polyethylene insulated wire is greatly deformed by hot-melt, and as a result, the flat cable obtained often has poor appearance collapse and dimensional defects. That is, in the case of a conventional round flat cable using a foamed polyethylene insulated wire, only a cable having low productivity and poor appearance and quality could be manufactured.

The present invention has been made in view of such a point, and an object of the present invention is to solve the above-mentioned disadvantages of the prior art, and to provide a good appearance of an intermediate product flat cable, thereby achieving a final product. It is an object of the present invention to provide a round flat cable having a good appearance, a high dimensional accuracy, and a remarkably high impedance between insulated wires.

[0017]

SUMMARY OF THE INVENTION The gist of the present invention is that a plurality of insulated wire pairs formed by twisting insulated wire cores are arranged in parallel in a longitudinal direction of a parallel-arranged insulated wire pair. The heat-sealed portion where the contact surfaces of the adjacent insulated wire pairs are respectively heat-sealed and the non-fused portion which is not heat-sealed are alternately repeated at predetermined intervals along In a round flat cable in which a sheath layer is provided on the outer periphery of a flat cable round body obtained by molding a flat cable into a round shape by alternately repeating a fused portion and a non-fused portion, the insulated wire core is ASTM-D- A round flat cable comprising a conductor coated with a thermoplastic olefin resin having a relative dielectric constant of 2.3 or less measured according to 1531.

In the present invention, the thermoplastic olefin resin having a relative dielectric constant of 2.3 or less is preferably one having an oxygen index of 25 or more.

In the present invention, the thermoplastic olefin resin having a relative dielectric constant of 2.3 or less may be a commercially available one or a specially synthesized one. Specific commercially available thermoplastic olefin resins having a relative permittivity of 2.3 or less include specific polyethylene, polypropylene, and copolymerized modified products thereof.

Examples of the material for the sheath layer include a vinyl chloride resin admixture, polyethylene, and fluorine resin.

A pressing tape can be wound around the outer circumference of the round flat cable, which is one of the intermediate products of the present invention, if necessary.

Further, a shielding material may be wound around the outer periphery of the flat cable round body which is one of the intermediate products of the present invention, if necessary, in addition to the holding tape.

Here, as the pressing tape, there are a plastic tape, for example, a polyethylene tape, a polypropylene tape, a polyamide resin tape, a fluororesin tape and the like.

The shielding material includes a metal wire, for example, a metal wire braid formed by braiding a thin copper wire or the like, or a metal tape, for example, a copper foil tape, an aluminum foil tape, a tin foil tape, or the like.

[0025]

Next, an embodiment of a round flat cable according to the present invention will be described together with a comparative example. (Example 1) A stranded conductor having a conductor size of 30 AWG was prepared by twisting tin-plated soft copper wires having a conductor diameter of 0.102 mm as a conductor.

Next, AST is placed on the stranded conductor prepared here.
An insulated wire was manufactured by coating the conductor with a thermoplastic olefin resin having a relative dielectric constant of 2.3 measured according to MD-1531.

The insulated wire having an insulating layer of 2.3 thermoplastic plastic olefin is used as an insulated wire core of a round flat cable. 80 insulated wires were manufactured.

Next, two wires were sequentially taken out of the 80-wire insulated electric wire having a relative permittivity of 2.3 thermoplastic plastic olefin, and then the two insulated electric wires having a relative permittivity of 2.3 thermoplastic plastic olefin were twisted. By doing so, 40 pairs of relative permittivity 2.3 thermoplastic olefin insulated wire pairs were prepared.

Next, the forty pairs of the thermoplastic resin olefin insulated wire pairs having a relative dielectric constant of 2.3 were arranged so as to be in contact with each other.

Next, the forty pairs of the thermoplastic resin olefin insulated wire pairs of 40 pairs arranged so as to be in contact with each other are placed adjacent to each other at a predetermined interval along the longitudinal direction. By providing a heat-fused portion and a non-heat-fused portion of the thermoplastic plastic olefin insulated wire pairs in this order, a fused portion and a non-fused portion are provided along the longitudinal direction. In this case, a thermoplastic olefin insulated flat cable having a relative dielectric constant of 2.3 was prepared.

Next, the relative permittivity of 2.3 where the fused portion and the non-fused portion are provided along the longitudinal direction obtained here.
Thermoplastic olefin insulated flat cable is twisted into a round shape with a twisting machine at a twisting pitch of 300 mm, and then a siludo metal tape is wound around its outer periphery,
Further, a plastic tape was wound thereon to form a flat cable round body.

Finally, a vinyl chloride resin mixture was extruded onto the outer periphery of the flat cable round body thus obtained so as to have a finished outer diameter of 11.0 mm, thereby obtaining the round flat flat cable of Example 1. The cable was manufactured.

FIG. 1 is a perspective explanatory view showing a state in which the holding plastic tape, the shield tape layer and the vinyl chloride resin admixture sheath layer have been cut off at the end of the round flat cable of Example 1 thus obtained. .

FIG. 2 is a sectional view taken along the line BB 'of the fused portion of the round flat cable of the first embodiment shown in FIG.

FIG. 3 is a sectional view of the non-fused portion of the round flat cable according to the first embodiment shown in FIG. 1 taken along the line BB '.

1 to 3, reference numeral 1 denotes a stranded conductor, 2 denotes a relative dielectric constant of 2.3 thermoplastic plastic olefin insulating layer, 3 denotes a holding plastic tape, 4 denotes a shield metal tape layer, and 5 denotes a vinyl chloride resin admixture sheath layer. It is. (Example 2) Example 1 except that a thermoplastic olefin insulated wire having a relative dielectric constant of 1.9 was used as an insulated wire core.
In the same manner as in the above, a round flat cable of Example 2 was manufactured. (Comparative Example 1) A round flat cable of Comparative Example 1 was manufactured in the same manner as in Example 1, except that a vinyl chloride resin-mixed insulated wire was used as the insulated wire of the insulated wire core. (Comparative Example 2) Example 1 except that a thermoplastic olefin insulated wire having a relative dielectric constant of 2.8 was used as an insulated wire core.
In the same manner as in the above, a round flat cable of Comparative Example 2 was manufactured. Comparative Example 3 A round flat cable of Comparative Example 3 was manufactured in the same manner as in Example 1 except that a foamed polyethylene insulated wire was used as an insulated wire core. (Test Method) Next, the thus obtained round flat cable of Example 1, the round flat cable of Example 2, the round flat cable of Comparative Example 1, the round flat cable of Comparative Example 2, and the like. The following test was performed on the round flat cable of Comparative Example 3. Appearance inspection The appearance of the obtained round flat cable was observed, and the presence or absence of crushing failure of the insulating layer was observed.

The results are indicated by ○ when there is no crush failure or the like, and are indicated by x when there is a crush failure or the like. Impedance measurement The impedance of the obtained round flat cable was measured by So
The measurement was performed using a TDR11801B test device manufactured by NY Tektronix. (Test results) Table 1 shows the results of these tests.

[0038]

[Table 1]

As can be seen from Table 1, the round flat cable of Comparative Example 1 corresponding to the conventional product has an impedance of 68Ω.
And the smallest.

The round flat cable of Comparative Example 2 in which a thermoplastic olefin exceeding the limited upper limit of the relative dielectric constant of the present invention is used as the insulated wire of the insulated wire as the insulating material also has a small impedance of 74Ω. .

The round flat cable of Comparative Example 3 in which the insulated wire of the insulated wire was a foamed polyethylene insulated wire had a large impedance of 87 Ω, but its half-face appearance was extremely poor.

On the other hand, the round flat cable according to the first embodiment of the present invention and the round flat cable according to the first embodiment have good appearance, high dimensional accuracy although not displayed, and impedance of 80 Ω or more. And it was high.

[0043]

The round flat cable of the present invention has good appearance, high dimensional accuracy, and high impedance characteristics, and is industrially useful.

[Brief description of the drawings]

FIG. 1 is a perspective explanatory view showing a state in which a holding plastic tape, a shield tape layer, and a vinyl chloride resin admixture sheath layer are cut off at an end of a round flat cable according to Embodiment 1 of the present invention.

FIG. 2 is an explanatory cross-sectional view of the fused portion of the round flat cable according to the first embodiment shown in FIG.

FIG. 3 is a cross-sectional view of the non-fused portion of the round flat cable according to the first embodiment shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Stranded conductor 2 Relative permittivity 2.3 Thermoplastic olefin insulating layer 3 Holding plastic tape 4 Shield metal tape layer 5 Vinyl chloride resin admixture sheath layer

Claims (3)

[Claims] An insulated wire pair comprising a plurality of twisted insulated wire pairs formed by twisting insulated wire cores and arranged in parallel. A flat-cable alternately-fused portion / non-fused portion in which a heat-fused portion where the contact surfaces of the bodies are heat-fused and a non-fused portion that is not heat-fused alternately repeats at a predetermined interval. In a round flat cable formed by providing a sheath layer on the outer periphery of a round flat body formed into a round shape, the insulated wire core has a relative dielectric constant of 2.3 or less measured according to ASTM-D-1531. A round flat cable comprising a conductor coated with a thermoplastic olefin resin. 2. The round flat cable according to claim 1, wherein the thermoplastic olefin resin having a relative dielectric constant of 2.3 or less has an oxygen index of 25 or more. 3. The sheath layer material is a vinyl chloride resin admixture,
2. The round flat cable according to claim 1, wherein the cable is one selected from polyethylene and fluororesin.