JP3596726B2 - Coaxial cable with easy terminal processing - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to coaxial cables. More specifically, the present invention relates to a coaxial cable for high-frequency applications, which is used as an internal wiring material and a device lead wire of high-frequency devices, has a two-layer outer conductor, and has good flexibility which is easy to handle .
[0002]
[Prior art]
2. Description of the Related Art Coaxial cables used as internal wiring materials and lead wires of information electronic devices and industrial devices are required to have various characteristics as performance and functions of these devices are improved. In particular, with the development of high-frequency transmission technology, the application frequency of coaxial cables ranges from several GHz to over a dozen GHz, and the bandwidth is becoming even higher. Also, coaxial cables are required to have flexibility.
[0003]
A conventional flexible high-frequency coaxial cable has a thin slit copper tape as an outer conductor vertically attached to the outer periphery of an insulating core or spirally wound, and then a copper wire is directly braided outside the copper tape winding layer to form a two-layered structure. A configuration is known in which an external conductor is provided, and a jacket layer made of a thermoplastic resin is further provided on the outer periphery. In such a coaxial cable, it is possible to shield a wide frequency band by the copper tape winding layer and the copper wire braid, and the copper wire braid holds down the copper tape winding layer, so that the copper tape breaks during bending and The gap is prevented.
[0004]
[Problems to be solved by the invention]
However, in the above coaxial cable in which the outer conductor is a combination of a copper tape winding layer and a copper wire braid, stress when braiding the copper wire adversely affects the copper tape wound around the insulating core, thereby causing the copper tape There has been a problem that the overlapping portions of both side edges are shifted or distortion is easily left on the copper tape. Therefore, it has been difficult to bring the copper tape winding layer into close contact with the insulating core surface without any gap. In addition, the above coaxial cable has a structure in which the copper wire braid is directly applied to the outside of the copper tape winding layer, so that the frictional resistance between the two is large at the time of bending, and the copper tape is easily worn when the bending is repeated. I have. In addition, since the copper tape uses a slit product, burrs usually remain on both side edges of the copper tape, and when bending, the frictional resistance between the outer conductors of the two layers becomes larger, There was a problem that the wear of has been accelerated. In addition, the burrs at the edge portions cause the copper tape to break when the copper tape is wound.
[0005]
The present invention has been made in order to solve the above-mentioned various problems of the prior art, and has excellent vibration resistance, shock resistance, and durability associated with bending while having excellent shielding characteristics in a wide frequency band. Further, it is an object of the present invention to provide a coaxial cable for high frequency use which has flexibility in which terminal processing is easy.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, as a first aspect, the present invention relates to a coaxial cable in which an insulator, a two-layer outer conductor and a jacket are sequentially coated on the outer periphery of a center conductor, wherein the inner outer conductor is provided. The metal tape is formed by spirally winding a smooth rolled metal tape without burrs on both sides of the metal tape, and the outer outer conductor is formed by a braided conductor, and a tape winding layer is formed between the inner and outer outer conductors. as the thickness t, 0.01 mm <t <thermofusible tree butter tape winding layer of 0.03 mm (hereinafter, abbreviated as the resin tape winding layer) is facilitated coaxial cable terminal processing is interposed.
[0007]
In the coaxial cable according to the first aspect, since the inner outer conductor is formed on the outer periphery of the insulating core by spirally wrapping a rolled metal tape, both sides of the metal tape are compared with the case where the conventional slit metal tape is used. Since there is no burr at the edge portion of the metal tape, the metal tape overlap portion has a small frictional resistance at the time of bending and has an advantage that it is not easily worn. In addition, since a resin tape winding layer having a thickness t of 0.01 mm <t <0.03 mm as a tape winding layer is interposed between the two outer conductors, the resin tape winding layer is formed by the inner rolled metal. Since the winding state is maintained by uniformly surrounding the entire outer peripheral surface of the tape winding layer, the conductor resistance does not change due to the displacement of the metal tape winding layer during bending or vibration, and metal Since the tape winding layer is closely adhered to the outer peripheral surface of the insulating core without any gap, the stability of the electrical characteristics is greatly improved. Further, the resin tape winding layer also has a function of relaxing stress and bending stress and external impact at the time of forming the braided conductor and preventing them from directly reaching the metal tape winding layer.
[0008]
In addition, the resin tape winding layer is located between the braided conductor layer whose inner surface is not smooth and the metal tape winding layer, and prevents direct contact between the two. Slip occurs through the winding layer, and good flexibility is obtained. In addition, since the heat-fusible resin tape is used, the two-layer outer conductor and the resin tape winding layer provided therebetween can be collectively terminal-processed. Further, since the resin tape is very thin, the increase in the finished outer diameter of the cable is at a negligible level. Another reason for using the rolled metal tape for the inner outer conductor is that even when a very thin resin tape as described above is used, the metal tape edge is smooth, so the resin tape does not wear. The point is to maintain the slipperiness between the two layers of the outer conductor.
[0009]
According to the preliminary experiment, even when the thickness t of the resin tape winding layer was 0.03 mm or more, the vibration resistance and the impact resistance were good, but the bending characteristics were reduced and the finished outer diameter of the cable was increased. When the thickness t of the resin tape winding layer was 0.01 mm or less, the workability was poor due to too thin, and the mechanical strength was insufficient.
[0010]
The present invention as the second aspect is that the pre-Symbol resin tape winding layer provided on the outer conductor and between the two layers, to facilitate coaxial cable terminal processing of the first aspect of the terminal processed collectively.
[0011]
In the coaxial cable according to the second aspect, the two- layer outer conductor and the resin tape winding layer provided therebetween are collectively subjected to the terminal treatment, so that the terminal workability is excellent.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the present embodiment.
FIG. 1 is a partially cutaway side view for explaining the structure of the coaxial cable of the present invention. In FIG. 1, 1 is a center conductor, 2 is an insulator, 3 is an inner outer conductor (rolled metal tape winding layer), 4 is a resin tape winding layer, 5 is an outer outer conductor (braided conductor layer), Reference numeral 6 denotes a jacket, and reference numeral 7 denotes a coaxial cable whose terminal processing is easy .
[0013]
-1st Embodiment-
In the coaxial cable 7 of the present invention, a silver-plated soft copper wire having an outer diameter of 0.912 mm is used as the central conductor 1, and the outer periphery thereof is coated with an unsintered porous PTFE resin to a thickness of 0.87 mm to form an insulator 2. The outer conductor includes an inner outer conductor 3, a resin tape winding layer 4, an outer outer conductor 5, and a jacket 6 on the outer periphery, and the outer conductor has a two-layer structure.
[0014]
For example, the center conductor 1 is a silver-plated soft copper wire having an outer diameter of 0.912 mm, the insulator 2 is a non-sintered porous PTFE resin coated with a thickness of 0.87 mm, and the inner outer conductor is Reference numeral 3 denotes a roll of rolled silver-plated soft copper foil having a thickness of 0.04 mm spirally wound and the outer conductor 5 on the outside is formed by braiding 96 silver-plated soft copper wires having an outer diameter of 0.12 mm. The jacket 6 is formed by extruding a fluororesin tetrafluoroethylene-hexafluoropropylene copolymer resin (FEP). The thickness t of the resin tape winding layer 4 made of polyphenylene sulfide resin (PPS) is provided between the two outer conductors 3 and 5, for example, to a thickness of 0.012 mm.
[0015]
In addition, as the resin tape winding layer 4, a polyethylene terephthalate resin (PET), a polyester resin, or various other heat-meltable resin tapes may be used in addition to the PPS tape. As the jacket 6, in addition to the above-mentioned FEP, a fluorine-based resin such as tetrafluoroethylene-perfluoroalkylvinyl ether resin (PFA) or tetrafluoroethylene-ethylene copolymer resin (ETFE) is preferably used. Depending on the required characteristics of mechanical strength, other synthetic resins can be used.
[0016]
-2nd Embodiment-
The thickness t of the resin tape winding layer 4 made of PPS is set to 0.028.
A coaxial cable 7 was manufactured in the same manner as in the first embodiment except that the coaxial cable 7 was provided in a thickness of mm.
[0017]
-Third embodiment-
An example is shown in which the coaxial cable according to the first embodiment of the present invention is used to collectively terminate the two outer conductors and the resin tape winding layer provided therebetween. (Not shown)
[0018]
First, the jacket 6 was peeled off by a strip jig for a certain length, and then the inner outer conductor 3, the resin tape winding layer 4 and the outer outer conductor 5 were immersed in a solder bath and subjected to a batch soldering. Then, the coaxial cable subjected to the soldering is subjected to terminal processing in the order of the layers 3, 4, 5 integrated with the soldering, the insulator 2, and the center conductor 1 by an automatic terminal processing machine in order of assembling (connecting the connector). ).
[0019]
According to the third embodiment of the present invention, the resin tape winding layer 4 is extremely thin, and the resin tape is made of a heat-meltable resin such as PPS. It disappears at the raised portion, and the inner outer conductor 3 and the outer outer conductor 5 are integrated. Therefore, the man-hours for processing the cable are equivalent to those of the conventional cable, which is good.
[0020]
Comparative form-first comparative form-
The coaxial cable of Comparative Embodiment 1 is the same as the coaxial cable 7 of the first embodiment of the present invention except that the thickness t of the resin tape winding layer 4 made of PPS is 0.100 mm. It was manufactured in the same manner.
[0021]
-Second comparison form-
Coaxial cable of Comparative Embodiment 2, the a coaxial cable 7 of the second embodiment of the present invention, as an external conductor 3 on the inner side, except for using a slit metal tape of thickness 0.04mm the second embodiment It was manufactured in the same manner as described above.
[0022]
Characteristics test The vibration resistance and the bending characteristics of the coaxial cable obtained by the above-described embodiment and the comparative example were tested, and the outer conductor diameter of the conventional high-frequency coaxial cable without the resin tape winding layer 4 was measured. It was compared with the outer conductor diameter.
The vibration resistance was evaluated as follows: As a vibration test, an assembly with a sample length of 1,000 mm was hit on a metal plate at 5 cycles / second, and the insertion loss before and during the test (when vibrated for 3 minutes). Was measured and compared. As a method of evaluating the bending characteristics, a bending test was performed by bending a portion of 150 mm from the connector end of an assembly product having a sample length of 1,000 mm at a bending radius of 50 mm, bending at 180 degrees, 2 seconds / cycle, and 1,000 cycles. The return loss before and after bending was measured and compared.
The results are shown in Table 1 below. FIGS. 2 to 5 show examples of an insertion loss chart in the vibration test and a return loss chart in the bending test.
[0023]
[Table 1]
[0024]
As is clear from the results in Table 1, a rolled metal tape was used for the inner outer conductor, and a thickness t of the tape winding layer between the inner and outer outer conductors was 0.01 mm <t <0. It can be seen that the coaxial cable of the present invention in which the 03 mm synthetic resin tape winding layer is interposed has excellent bending characteristics and a minimum increase in the outer diameter of the outer conductor as compared with the coaxial cable of the comparative example.
[0025]
【The invention's effect】
The coaxial cable of the present invention uses a rolled metal tape for the inner outer conductor, and a resin tape of 0.01 mm <t <0.03 mm as the thickness t of the tape winding layer between the inner and outer outer conductors. By providing the winding layer, without having to increase the outer diameter of the outer conductor, it has excellent vibration resistance and shock resistance, and has excellent durability with bending, while having excellent shielding characteristics in a wide frequency band. A coaxial cable having good flexibility and excellent terminal workability was obtained. Therefore, the present invention has an extremely large effect of contributing to industry.
[Brief description of the drawings]
FIG. 1 is a partially cutaway side view for explaining the structure of a coaxial cable of the present invention.
FIG. 2 is a chart showing insertion loss before and during a vibration test of the coaxial cable of the present invention.
(1) is the coaxial cable of the first embodiment.
(2) is the coaxial cable of the second embodiment.
FIG. 3 is a chart showing insertion loss before and during a vibration test of a coaxial cable of a comparative example.
(1) is a coaxial cable of Comparative Example 1.
(2) is a coaxial cable of Comparative Example 2.
FIG. 4 is a chart showing the return loss before and after a bending test of the coaxial cable of the present invention. (1) is before bending of the coaxial cable of the first embodiment.
(2) shows the state after bending the coaxial cable of the first embodiment.
(3) is before bending of the coaxial cable of the second embodiment.
(4) shows the state after bending the coaxial cable of the second embodiment.
FIG. 5 is a chart showing return loss before and after a bending test of a coaxial cable of a comparative embodiment.
(1) is before bending of the coaxial cable of Comparative Example 1.
(2) shows the state after bending of the coaxial cable of Comparative Example 1.
(3) is before bending of the coaxial cable of Comparative Embodiment 2.
(4) is the state after bending of the coaxial cable of Comparative Example 2.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Center conductor 2 Insulator 3 Inner outer conductor (rolled metal tape winding layer)
4 Synthetic resin tape winding layer 5 Outer outer conductor (braided conductor layer)
6 Jacket 7 Coaxial cable with easy termination

Claims (2)

In a coaxial cable in which an insulator, a two-layer outer conductor and a jacket are sequentially coated on the outer periphery of a center conductor, the inner outer conductor is formed by a spiral of a smooth rolled metal tape without burrs on both edges of the metal tape. formed by lap winding, and the outside of the outer conductor so as to form a braided conductor, between said inner and outer of the outer conductor, as the thickness t of the tape winding layer, 0.01 mm <t <0.03 mm of the heat easy coaxial cable terminal processing, characterized in that by interposing a fusible tree butter tape winding layer. The thermofusible tree butter tape winding layer provided on the outer conductor and between the previous SL two layers, collectively easy coaxial cable terminal treatment according to claim 1, characterized in that the terminal processing.