JP3918643B2 - Extra fine multi-core cable - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrafine multi-core coaxial cable using a coaxial wire having an outer diameter of an inner conductor of 0.08 mm or less.
[0002]
[Prior art]
With the downsizing of electronic devices, IC testers, and medical devices, device wires applied to them are also becoming thinner. Further, with higher performance of devices (for example, higher definition of images, higher communication speed, etc.), higher transmission quality is required for transmission between devices and within devices.
[0003]
Furthermore, power / signal transmission cables used in medical devices, notebook computers, industrial robots, and the like may be broken due to metal fatigue by being repeatedly bent during use.
[0004]
Therefore, a cable used in such a device has improved bending resistance by using a stranded wire obtained by twisting a large number of thin strands to reduce the amount of strain applied to each strand.
[0005]
FIG. 4 shows an example of a coaxial line used in a conventional ultrafine multi-core coaxial cable.
[0006]
As shown in the drawing, the coaxial line 51 has a central conductor 53 formed by twisting a plurality of conductors (element wires) 52 at the center thereof. An insulator 54 is provided around the center conductor 53, and a plurality of external conductors 55 are twisted and arranged around the insulator 54. An insulator 56 is provided around the outer conductor 55, and a jacket 57 is provided on the outermost periphery.
[0007]
[Problems to be solved by the invention]
However, in the conventional coaxial wire 51 as described above, since the stranded wire is used for the central conductor 53, although the flexibility is excellent, the arrangement of the strands in the stranded wire collapses at the time of terminal connection, There is a problem that an electrical short circuit may occur at the terminal portion.
[0008]
Further, in order to produce a stranded wire, the constituent wires must be drawn finely and twisted together, which requires a lot of labor for production, and the cost increases accordingly.
[0009]
Therefore, the present invention has been devised to solve the above problems, and its purpose is excellent in terminal processability, can prevent electrical short-circuiting, can easily connect cables at low cost, and is flexible. It is to provide an ultra-fine multi-core coaxial cable excellent at low cost.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides an ultrafine multi-core coaxial cable having a coaxial wire having an inner conductor, an insulator, and an outer conductor having a conductor diameter of 0.08 mm or less, wherein the inner conductor has a tensile strength of 1000 MPa. The outer conductor is composed of a single wire having an elongation of 1% or more and an electrical conductivity of 70% IACS, and the outer conductor has an outer diameter of 0.012 mm or more, a tensile strength of 700 MPa or more, an elongation of 1% or more, and an electrical conductivity. The ratio P / Pd between the twisting pitch P and the twisted outer diameter Pd of the cable formed by twisting strands of 60 % IACS or more and formed by twisting a plurality of the coaxial wires is in the range of 25-60. It is intended to be inside .
[0011]
The insulator covering the inner conductor and the jacket covering the outer conductor are made of fluororesin, ultraviolet curable resin, polyethylene, polyphenylene sulfide, polyimide or polyester, and the coating thickness is 20 μm or more. Is preferred.
[0012]
Further, the tensile strength of the inner conductor is 50% or less of the tensile strength of the entire cable, the tensile strength of the outer conductor is 30% or more of the tensile strength of the entire cable, and covers the insulator and the coaxial wire. those tensile strength of the jacket is at least 5% of the tensile strength of the entire cable respectively to is preferred.
[0013]
And what provided the tension member which has the tensile strength equivalent to 10% or more of the tensile strength of the whole cable inside the said coaxial line or the center part of the cable is preferable.
[0014]
In addition, a collective shield is provided on the outer periphery of the coaxial wire, and the collective shield is composed of an annealed copper wire, a copper alloy wire, and a copper foil thread, and its tensile strength is 5% or more of the tensile strength of the entire cable. Are preferred.
[0015]
Further, the sheath constituting the outermost layer of the cable is made of fluororesin, ultraviolet curable resin, polyethylene, polyimide or polyvinyl chloride, the sheath has a Shore A hardness of 60 or more, and has a tensile strength. What is 1% or more of the tensile strength of the whole cable is preferable.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0017]
FIG. 1 is a cross-sectional view showing a preferred embodiment of an ultra-fine multi-core coaxial cable according to the present invention, and FIG. 2 is an enlarged cross-sectional view showing a coaxial line constituting the ultra-fine multi-core coaxial cable according to the present invention.
[0018]
As shown in FIG. 2, the coaxial wire 2 constituting the ultra-fine multi-core coaxial cable 1 according to the present embodiment has a tensile strength of 1000 MPa or more (1100 MPa in the present embodiment) and an elongation of 1% at the center. A single wire of a silver-plated copper alloy wire having the above (1% in the present embodiment), an electrical conductivity of 70% or more, and an outer diameter of 0.08 mm (AGW (American Wire Gauge) gauge value of 40) It has an inner conductor 3 made of
[0019]
Here, the tensile strength of the inner conductor 3 was set to 1000 MPa, and it was discovered that there is a relationship between the strength of the conductor in the coaxial wire and the bending resistance, and a conventionally used stranded wire made of a copper alloy strand and It is because it discovered that it was required in order to obtain the same level of bending resistance.
[0020]
An insulator 4 is provided on the outer periphery of the inner conductor 3. This insulator 4 is composed of PFA (tetrafluoroethylene / perfluoropropyl vinyl ether copolymer), FEP (tetrafluoroethylene / hexafluoropropylene copolymer), ETFE (ethylene / tetrafluoroethylene copolymer). And a fluororesin such as PTFE (tetrafluoroethylene resin), and the coating thickness is 20 μm or more. In addition, the material which comprises the insulator 4 is not restricted to a fluororesin, An ultraviolet curable resin, polyethylene, polyphenylene sulfide (PPS), a polyimide, polyester, etc. may be sufficient.
[0021]
On the outer periphery of the insulator 4, the tensile strength is 700 MPa or more (800 MPa in the present embodiment), the elongation is 1% or more (1% in this embodiment), the conductivity is 60 % IACS or more, and the outer diameter is 0.00. An outer conductor 6 formed by twisting strands 5 made of tin-plated copper alloy wires of 012 mm or more (0.03 mm in the present embodiment) in a spiral shape is provided.
[0022]
A plating layer 7 and a jacket 8 are formed on the outer periphery of the outer conductor 6. The jacket 8 is made of a polyester tape, and the thickness thereof is 20 μm or more. The material constituting the jacket 8 is not limited to polyester, but PFA (ethylene tetrafluoride / perfluoropropyl vinyl ether copolymer), FEP (tetrafluoroethylene / hexafluoropropylene copolymer), Fluorine resin such as ETFE (ethylene / tetrafluoroethylene copolymer) and PTFE (tetrafluoroethylene resin), ultraviolet curable resin, polyethylene, polyphenylene sulfide (PPS), polyimide, or the like may be used.
[0023]
Here, the material of the jacket 8 and the insulator 4 described above is limited, and the thickness thereof is set to 20 μm or more in order to maintain sufficient insulation performance when the cable is bent.
[0024]
Regarding the distribution of the tensile strength of each part of the coaxial wire 2, the tensile strength of the inner conductor 3 is 50% or less of the tensile strength of the coaxial wire 2, and the tensile strength of the outer conductor 6 is 30% of the tensile strength of the coaxial wire 2. or more, the tensile strength of the insulator 4 and the jacket 8 is set to be the least 5% of the tensile strength of the coaxial line.
[0025]
Here, the reason why the strength ratio of each component of the coaxial line 2 is set is that the strength ratio of the component is found to be closely related to the bending resistance of the ultrafine multi-core cable 1.
[0026]
An example of the ultrafine multi-core coaxial cable 1 having the coaxial line 2 having the above-described configuration is shown in FIG. This ultrafine multi-core coaxial cable 1 has 132 coaxial wires 2 having a layer core diameter ratio which is a ratio P / Pd of a twist pitch P and a twist outer diameter Pd within a range of 25 to 60 (this embodiment Is formed by twisting so as to be 40).
[0027]
Here, the reason why the ratio between the twisting pitch and the twisted outer diameter is set is that it has been found that this layer core diameter ratio is related to the ultrafine multi-core coaxial cable 1 and the bending characteristics.
[0028]
Specifically, four central-side multi-core cables 11 formed by twisting five coaxial wires 2 are arranged and twisted on a concentric circle, and a tension member 9 having a tensile strength of 300 N is provided at the center. ing. The tension member 9 is not limited to the above numerical values, and is set so as to correspond to 10% or more of the tensile strength of the entire ultrafine multi-core cable 1.
[0029]
Here, the reason why the strength of the tension member 9 is set is that it has been found to be greatly involved in improving the bending resistance of the ultrafine multi-core coaxial cable 1. Moreover, it is for making it the structure which can endure when an excessive tensile force is applied to a cable.
[0030]
A plurality of outer multi-core cables 12 having 16 coaxial wires 2 are provided outside the center-side multi-core cable 11. The outer multi-core cable 12 has five coaxial lines 2 arranged concentrically on the center side and eleven coaxial lines 2 arranged concentrically on the outer side. Then, seven outer multi-core cables 12 are arranged on a concentric circle and twisted together.
[0031]
A presser winding tape 14 is wound around the outer side of the twisted outer multi-core cable 12, and a collective braided shield 15 is provided on the outer periphery thereof. The collective braided shield 15 is composed of tin-plated copper foil thread, and is formed so that its tensile strength is 5% or more of the tensile strength of the entire ultrafine multi-core cable 1. In addition, the raw material of the collective braided shield 15 is not limited to copper foil yarn, and may be composed of an annealed copper wire, a copper alloy wire, or the like.
[0032]
Here, the one-piece braided shield 15 is provided to reduce the noise radiated from the cable and to withstand the bending force received during use while having a shielding characteristic for blocking the noise from the outside. Is because it was discovered that the strength of the braid needs to be controlled.
[0033]
A sheath 16 constituting the outermost layer of the ultrafine multi-core coaxial cable 1 is provided on the outer periphery of the collective braided shield 15. The sheath 16 is made of polyvinyl chloride (PVC) having a Shore A hardness of 60 or more (65 in the present embodiment), and has a thickness of 0.8 mm. The sheath 16 is formed so that its tensile strength is 1% or more of the tensile strength of the entire ultrafine multi-core cable 1.
[0034]
Here, the reason why the material and strength of the sheath 16 are limited is that it has been found that it is necessary to withstand bending during use and to obtain sufficient flexibility. The tensile strength of the sheath 16 is more preferably 3% or more of the tensile strength of the entire ultrafine multi-core cable 1.
[0035]
Next, we investigated the shielding characteristics, flexibility, connection workability, manufacturing cost ratio, and bending life of the ultra-thin multi-core coaxial cable 1 configured as described above and a plurality of comparative examples shown below, and compared the results. The operation of the ultrafine multi-core coaxial cable 1 according to the present embodiment will be described.
[0036]
The manufacturing cost ratio is a comparative value with the cost for the extra fine multi-core coaxial cable 1 being 100. The flexing life indicates the number of flexing times when the test was conducted under the conditions of R = 12.7 mm and W = 4.9N and fractured.
[0037]
In Comparative Example 1, the portion corresponding to the inner conductor 3 of the coaxial wire 2 of the ultrafine multi-core coaxial cable 1 was replaced with a stranded wire (7 wires / 0.03 mm) of silver-plated copper alloy wire having a tensile strength of 800 MPa. Is.
[0038]
In Comparative Example 2, the portion corresponding to the inner conductor 3 of the coaxial wire 2 of the ultrafine multi-core coaxial cable 1 is replaced with a silver-plated copper wire (1 wire / 0.08 mm) having a tensile strength of 200 MPa. is there.
[0039]
In Comparative Example 3, the portion corresponding to the outer conductor 6 of the coaxial line 2 of the ultrafine multi-core coaxial cable 1 is replaced with a tin-plated copper wire having a tensile strength of 400 MPa.
[0040]
In Comparative Example 4, the portion corresponding to the outer conductor 6 of the coaxial line 2 of the ultrafine multi-core coaxial cable 1 is replaced with a tin-plated copper alloy wire having a tensile strength of 600 MPa.
[0041]
In Comparative Example 5, the layer core diameter ratio P / Pd, which is the ratio of the twisting pitch P and the twisted outer diameter Pd of a cable formed by twisting a plurality of coaxial wires 2, is 10.
[0042]
In Comparative Example 6, the layer core diameter ratio P / Pd, which is the ratio of the twisting pitch P of the cable formed by twisting a plurality of coaxial wires 2 and the twisted outer diameter Pd, is 70.
[0043]
In Comparative Example 7, the tension member 9 at the center of the ultrafine multi-core coaxial cable 1 is removed.
[0044]
In Comparative Example 8, the portion corresponding to the collective braided shield 15 of the ultrafine multi-core coaxial cable 1 is formed of an annealed copper wire having a tensile strength of 200 MPa and a strand diameter of 0.05 mm, and the tensile strength is ultrafine multicore coaxial. This is 3% of the tensile strength of the entire cable 1.
[0045]
In Comparative Example 9, the portion corresponding to the sheath 16 of the above-mentioned ultrafine multi-core coaxial cable 1 is formed with a thickness of 0.3 mm by a material having a Shore A hardness of 55, and the tensile strength thereof is very fine multi-core coaxial cable. 1 is formed so as to be 0.5% of the tensile strength of the whole.
[0046]
The comparative survey results of the ultra-thin multi-core coaxial cable 1 according to the present embodiment and the ultra-thin multi-core coaxial cables of Comparative Examples 1 to 9 are as shown in the characteristic survey result comparison table of the ultra-thin multi-core coaxial cable in FIG. It was.
[0047]
As for the shielding characteristics, at frequencies of 0.3 MHz to 1 GHz, those other than Comparative Example 8 including the ultrafine multi-core coaxial cable 1 according to the embodiment of the present invention are 70 to 75 (dB), and Comparative Example 8 is 60 to 60. It was 65 (dB).
[0048]
Regarding the flexibility, both the ultra-thin multi-core coaxial cable 1 of the embodiment of the present invention and Comparative Examples 1 to 9 were very good as compared with the conventional one.
[0049]
Regarding the connection workability, the comparative example 1 was slightly bad, but the comparative examples 2 to 9 including the ultrafine multi-core cable 1 of the embodiment of the present invention were good.
[0050]
Regarding the manufacturing costs, those of Comparative Examples 1, 5, and 8 are slightly higher, those of Comparative Examples 4, 6, and 9 are substantially the same, and those of Comparative Examples 2, 3, and 7 are slightly cheaper.
[0051]
Regarding the bending life, the number of the ultra-fine multi-core coaxial cable 1 according to the embodiment of the present invention is 2.3 million times, whereas that of the comparative example 1 is 2 million times and that of the comparative example 5 is 1.9 million times. Except for the above, the overall length was low, and in the case of Comparative Example 2, the bending life was very short at 49,000 times.
[0052]
When these results are put together, the thing of the comparative example 1 has bad connection workability | operativity, and its manufacturing cost is high. Although the thing of the comparative example 2 is cheap in manufacturing cost, a bending life is extremely short. Although the thing of the comparative example 3 is cheap in manufacturing cost, a bending life is short. The thing of the comparative example 4 has a short bending life. The thing of the comparative example 5 has a high manufacturing cost. The thing of the comparative example 6 has a short bending life. Although the thing of the comparative example 7 is cheap in manufacturing cost, a bending life is short. The thing of the comparative example 8 has a bad shield characteristic. The thing of the comparative example 9 has a short bending life.
[0053]
That is, the ultra-thin multi-core coaxial cable 1 according to the embodiment of the present invention can obtain good results in all parts in shielding characteristics, flexibility, terminal processability, manufacturing cost, and bending life. Can be balanced at a high level.
[0054]
In particular, the terminal processability and the bending life are significantly improved as compared with the conventional coaxial cable 2 using a twisted wire as the inner conductor, and the manufacturing cost is reduced during cable assembly and the reliability of the cable is improved. Such an effect can be obtained.
[0055]
In short, according to the present invention, the inner conductor 3 of the coaxial line 2 has a tensile strength of 1000 MPa or more (1100 MPa in the present embodiment), an elongation of 1% or more (1% in the present embodiment), and an electrical conductivity of 70%. As described above, the outer diameter is 0.08 mm (AGW (American Wire Gauge) gauge value is 40). Connection can be easily made at low cost, and an electrical short circuit can be prevented from occurring at the terminal portion as in the conventional case. In addition, it is possible to provide an ultra-fine multi-core coaxial cable that is significantly superior in flexibility as compared with conventional ones at a low cost.
[0056]
As another embodiment, the outer conductor 6 of the coaxial line 2 may be heat treated to adjust the elongation to 5% or more. According to the present embodiment, it is possible to obtain the same operation as that of the above-described embodiment of FIGS.
[0057]
【The invention's effect】
In short, according to the present invention, it is possible to reduce the number of coaxial cables excellent in flexibility, excellent in terminal processability, preventing an electrical short circuit in the terminal portion, easily connecting the cable at low cost, and excellent in flexibility. It exhibits an excellent effect that it can be provided at a low cost.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a preferred embodiment of an extra fine multi-core coaxial cable according to the present invention.
FIG. 2 is an enlarged cross-sectional view showing a coaxial line constituting an extra fine multi-core coaxial cable according to the present invention.
FIG. 3 is a comparison table showing the results of a characteristic investigation between the ultra-fine multi-core coaxial cable according to the present embodiment and the ultra-fine multi-core coaxial cable of the comparative example.
FIG. 4 is an enlarged cross-sectional view showing a coaxial line constituting a conventional ultrafine multi-core coaxial cable.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Extra-fine multi-core coaxial cable 2 Coaxial line 3 Inner conductor 4 Insulator 5 Element 6 External conductor 8 Jacket 9 Tension member 15 Collective (braid) shield 16 Sheath

Claims (6)

In an ultrafine multi-core cable having a coaxial wire composed of an inner conductor having an inner diameter of 0.08 mm or less, an insulator, an outer conductor and a jacket, the inner conductor has a tensile strength of 1000 MPa or more, an elongation of 1% or more The outer conductor is composed of a single wire having a rate of 70% IACS or more, and the outer conductor is twisted with an outer diameter of 0.012 mm or more, a tensile strength of 700 MPa or more, an elongation of 1% or more, and a conductivity of 60 % IACS or more. The ratio P / Pd of the twisting pitch P and the twisted outer diameter Pd of the cable formed by twisting a plurality of the coaxial wires is in the range of 25 to 60. Multi-core coaxial cable.   2. The insulator covering the inner conductor and the jacket covering the outer conductor are made of fluororesin, ultraviolet curable resin, polyethylene, polyphenylene sulfide, polyimide or polyester, and the coating thickness is 20 μm or more. The described ultra-fine multi-core coaxial cable. The tensile strength of the inner conductor is 50% or less of the tensile strength of the coaxial line, the tensile strength of the outer conductor is 30% or more of the tensile strength of the coaxial line, and the tensile strength of the insulator and the jacket There superfine multi-core coaxial cable according to any one of claims 1 or 2, respectively at least 5% of the tensile strength of the coaxial line. The ultrafine multi-core coaxial cable according to any one of claims 1 to 3 , wherein a tension member having a tensile strength corresponding to 10% or more of the tensile strength of the entire cable is provided inside the coaxial line or in the center of the cable. A collective shield is provided on the outer periphery of the coaxial wire, and the collective shield is composed of an annealed copper wire, a copper alloy wire, and a copper foil thread, and its tensile strength is 5% or more of the tensile strength of the entire cable. The ultrafine multi-core coaxial cable according to any one of claims 1 to 4 . The sheath constituting the outermost layer of the cable is made of fluororesin, ultraviolet curable resin, polyethylene, polyimide or polyvinyl chloride, the Shore A hardness of the sheath is 60 or more, and the tensile strength of the entire cable The ultrafine multi-core cable according to any one of claims 1 to 5, which has a tensile strength of 1% or more.

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