JP4461750B2 - Coaxial cable, coaxial cable manufacturing apparatus, and coaxial cable manufacturing method - Google Patents

Description

  The present invention relates to a coaxial cable, an apparatus for manufacturing the same, and a method for manufacturing the same, and more particularly to an ultrafine coaxial cable used for medical equipment, electronic information equipment, and the like, an apparatus for manufacturing the same, and a method for manufacturing the same.

  Among the coaxial cables, those having a very small outer diameter (for example, less than 0.35 mm) are referred to as micro coaxial cables. As shown in FIG. 4, the conventional general micro coaxial cable 40 is provided with an insulating layer 42 made of an insulator such as a fluororesin on the outer periphery of a central conductor (inner conductor) 41 formed by twisting strands. The outer periphery of the insulating layer 42 is provided with a shield layer (outer conductor) 43 and a jacket 44 formed by winding the strands in order. Here, the shield layer 43 shields electromagnetic noise in a high frequency region. Moreover, as a strand which comprises the center conductor 41 and the shield layer 43, the Cu-0.3mass% Sn alloy wire etc. whose strand diameter is 0.03 mm are used. Further, PFA or the like is generally used as the fluororesin constituting the insulating layer 42, and PET or PFA or the like is generally used as the jacket 44.

  In recent years, demands for weight reduction, miniaturization, and thinning of medical devices and electronic information devices have been increasing, and further ultrafine coaxial cables have been demanded.

  Here, the central conductor 41 is a Cu-2 mass% Ag alloy wire having a strand diameter of 0.016 mm, the constituent material of the insulating layer 42 and the jacket 44 is PFA, and the shield layer 43 is a Cu wire having a strand diameter of 0.02 mm. There is an ultra-fine coaxial cable composed of -0.2mass% Sn-0.2mass% In alloy wire with an outer diameter of around 0.205mm.

  Further, since the ultrafine coaxial cable 40 having the structure shown in FIG. 4 has a limit in reducing the diameter, various ultrafine coaxial cables having a cable structure different from the cable 40 have been proposed. For example, there is a coaxial cable in which the shield layer is formed of a metal thin film in the structure of the cable 40 (see, for example, Patent Documents 1 and 2).

Japanese Patent No. 2929161 JP 2002-203437 A

  However, the above-described ultra-fine coaxial cable having an outer diameter of about 0.205 mm has a problem that it takes a long time to form the shield layer 43 because the shield layer 43 is formed by winding the strands horizontally. . Moreover, since the strand which comprises the center conductor 41 is very thin, when the rigidity of the center conductor 41 was low and sudden external force acted at the time of formation of the shield layer 43, there existed a problem that a wire will deform | transform.

  Although the coaxial cable described in Patent Document 1 is highly effective in reducing the outer diameter of the cable, the manufacturing process is very complicated, resulting in an increase in manufacturing cost and a problem in mass productivity.

  Although the coaxial cable described in Patent Document 2 is also highly effective in reducing the outer diameter of the cable, a shield layer (metal thin film) is directly formed on the surface of the insulating layer by metal plating (electroless plating, electrolytic plating). Yes. Here, the general electroless plating has a problem that the film formation rate is extremely slow and is not realistic. In addition, in order to form a shield layer by electrolytic plating, it is necessary to form a conductive layer in advance on the surface to be plated, which causes an increase in the number of processes. Further, since the shield layer is provided directly on the surface of the insulating layer, there is a problem that it is difficult to peel off the shield layer when connecting the cable end of the coaxial cable.

  An object of the present invention created in view of the above circumstances is to provide a coaxial cable, a manufacturing apparatus thereof, and a manufacturing method thereof, which have almost no problems such as bending of the cable and have good productivity.

To achieve the above object, the coaxial cable according to the present invention is a coaxial cable having an insulating layer and a shield layer on the outer periphery of the center conductor, and a single wire material using a Cu-2 mass% Ag alloy wire or a Cu-2 mass% Ag alloy. A first insulating layer composed of a PFA film having a thickness of 0.033 mm is provided on the outer periphery of the central conductor made of a stranded wire made by twisting a plurality of wires, and a thickness of 0 is directly provided on the outer periphery of the first insulating layer. A second insulating layer composed of a .01 mm PET film is provided, and the shield layer composed of an Ag thin film by silver mirror reaction is provided on the outer periphery of the second insulating layer.

  According to the above configuration, the shield layer can be formed with high productivity, there are almost no problems such as bending of the cable, and the first insulating layer, the second insulating layer, and the shield layer can be easily peeled off. Can do.

  According to the present invention, an excellent effect is obtained that a coaxial cable having good bending characteristics can be obtained with high productivity.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a preferred embodiment of the invention will be described with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view of a coaxial cable according to a preferred embodiment of the present invention, and FIG. 2 is a cross-sectional view of a cable core used for manufacturing the coaxial cable of FIG. In FIG. 2, the same members as those in FIG.

  As shown in FIG. 1, the coaxial cable 10 according to the present embodiment includes a first insulating layer 12, a second insulating layer 13, a shield layer 14, and a jacket 15 in order on the outer periphery of the center conductor 11. It is. In other words, the coaxial cable 10 according to the present embodiment is obtained by sequentially providing the shield layer 14 and the jacket 15 on the outer periphery of the cable core 20 shown in FIG. Here, the second insulating layer 13 is provided directly on the outer periphery of the first insulating layer 12 without providing a fixing layer such as an adhesive layer.

  The first insulating layer 12 and the jacket 15 are preferably made of the same material. Examples of the constituent material include a fluororesin (for example, PFA). Moreover, as an insulator which comprises the 2nd insulating layer 13, when using PFA as a constituent material of the 1st insulating layer 12, PET (polyethylene terephthalate) is used as an insulator which comprises the 2nd insulating layer 13, for example. .

  Moreover, since the second insulating layer 13 is provided as a fixed layer of the shield layer 14 as described later, the thickness of the second insulating layer 13 is not particularly limited as long as the shield layer 14 can be sufficiently fixed. For example, it is sufficient if the thickness of the first insulating layer 12 is ½ or less, preferably ３ or less of the layer thickness.

  The shield layer 14 is intended to shield electromagnetic noise in a high frequency region, and is composed of an Ag thin film formed by a silver mirror reaction. The thickness of the Ag thin film is at least 1 μm or more, preferably 2 μm or more. If the thickness of the Ag thin film is less than 1 μm, electromagnetic noise shielding is insufficient.

  The center conductor 11 may be either a stranded wire obtained by twisting strands or a single wire made of one strand. Examples of the stranded wire include those obtained by twisting a plurality of (7 in FIG. 1) Cu-2 mass% Ag alloy wires having a strand diameter of 0.016 mm. Moreover, as a single wire, the Cu-2mass% Ag alloy wire whose strand diameter is 0.04 mm is mentioned, for example.

  Next, a method for manufacturing the coaxial cable 10 according to the present embodiment will be described.

  As a result of intensive studies by the present inventors, as a method of covering the outer periphery of the wire (cable core 20 (see FIG. 2)) with a shield layer, it is not a conventional horizontal winding of element wire, electroless plating, electrolytic plating, It has been found that a shield layer is formed with an Ag film by silver mirror reaction using silver mirror reaction.

  The coating formation of the Ag film by the silver mirror reaction is performed using a shield coating apparatus 30 shown in FIG. Specifically, the shield coating apparatus 30 mainly includes a sending means (sending bobbin) 32 that sends out the wound cable core 20, and a surface treatment means that performs a roughening process on the surface of the sent cable core 20. The silver mirror reaction tank 36 for forming an Ag thin film as a shield layer on the outer periphery of the cable core 20 whose surface is roughened, which is provided in the subsequent stage of the surface treatment means, and the winding for winding the cable core 20 covering the shield layer And means (winding bobbin) 37. The surface treatment means is provided in a subsequent stage of the surface roughening unit 34 for roughening the surface of the cable core 20 and the surface roughening unit 34, and the surface of the cable core 20 is degreased to perform acid cleaning. It is comprised with the tank 35. FIG. Further, pulleys 33a and 33b are provided between the means 32 and the surface roughening unit 34 and between the reaction vessel 36 and the means 37, respectively.

  The coating process of the shield layer 14 (see FIG. 1) using the shield coating apparatus 30 described above is composed of two steps: a surface roughening step and an Ag thin film coating step.

  First, after the first insulating layer 12 is formed on the outer periphery of the central conductor 11 by extrusion coating or the like, the second insulation is directly provided on the outer periphery of the first insulating layer 12 without providing a fixing layer such as an adhesive layer. The layer 13 is coated and the cable core 20 is produced. The cable core 20 is wound around a sending means (sending bobbin) 32 in advance.

  Next, the cable core 20 wound around the delivery means 32 is delivered and supplied to the surface roughening unit 34 of the surface treatment means. In the surface roughening unit 34, the outer periphery of the traveling cable core 20, that is, the outer periphery of the second insulating layer 13 is roughened by the plasma of nitrogen gas or argon gas by glow discharge (surface roughening step).

  Next, the surface-roughened cable core 20 is continuously supplied to a degreasing / pickling tank 35 provided at the subsequent stage of the surface roughening unit 34. In the degreasing / pickling tank 35, the traveling cable core 20 is immersed in a degreasing agent solution and also in an acid solution (for example, tin chloride aqueous solution), and the surface of the cable core 20 is degreased and pickled. (Surface roughening step). Here, the tin chloride aqueous solution is composed of, for example, a mixture of pure water, tin chloride, and hydrochloric acid.

  Next, the degreased / acid-washed cable core 20 is supplied to a silver mirror reaction tank 36 provided at a subsequent stage of the degreasing / pickling tank 35. In the silver mirror reaction tank 36, the traveling cable core 20 is immersed in an Ag plating solution, and an Ag thin film (shield layer 14 (see FIG. 1)) is formed on the outer periphery of the cable core 20 by a silver mirror reaction (Ag thin film). Coating step). At this time, since the outer periphery of the cable core 20 is roughened by the surface roughening step, the Ag thin film is coated in a state of being tightly adhered to the outer periphery of the cable core 20.

  Here, the film formation speed of the Ag thin film can be adjusted by adjusting the tank length of the reaction tank 36, the concentration and / or the mixing ratio of the Ag plating solution, for example, a high speed of 1.5 m / min or more. It is also possible to adjust the film forming speed. Further, the silver mirror reaction tanks 36 may be provided in multiple stages, and the Ag thin film may be formed in multiple layers. This makes it possible to obtain a thick Ag film (for example, a film thickness of 1 μm or more). Furthermore, the Ag plating solution is composed of an Ag solution obtained by mixing a silver nitrate aqueous solution, ammonia water, and the like, and a reducing solution obtained by dissolving glucose, formalin (registered trademark), etc. in pure water. When the reducing solution is a glucose solution, a small amount of nitric acid may be added to the reducing solution in order to decompose glucose.

  Thereafter, the shield-coated cable core 20 is wound around the winding means 37. Finally, the coaxial cable 10 shown in FIG. 1 is obtained by covering the outer periphery of the shield layer 14 having a sufficient thickness with the jacket 15 by extrusion coating or the like.

  In the method of manufacturing the coaxial cable 10 according to the present embodiment, the case where the coating process of the shield layer 14 and the coating process of the jacket 15 are separate processes has been described, but the present invention is not particularly limited thereto. Absent. For example, the jacket 15 may be covered between the silver mirror reaction tank 36 and the pulley 33b so as to cover the shield layer 14 and then cover the jacket 15 continuously.

  Next, the operation of the coaxial cable 10 according to the present embodiment will be described.

  In the coaxial cable 10 according to the present embodiment, the shield layer 14 is formed by a plating film method based on a silver mirror reaction instead of a winding method in which a strand is wound horizontally like the conventional coaxial cable 40 shown in FIG. It is done by. For this reason, when the shield layer 14 is formed around the cable core 20, there is no risk of sudden external force acting on the cable core 20, and thus problems such as deformation and bending of the cable core 20 occur. There is hardly any.

  As a result, according to the coaxial cable 10 according to the present embodiment, the frequency of occurrence of problems such as cable bending is extremely low, about 1/20 or less, as compared with the conventional coaxial cable 40 using a winding method, and the yield is reduced. In addition to being significantly improved, the bending characteristics are also improved. Therefore, it is possible to obtain the coaxial cable 10 with high productivity (inexpensive) and excellent bending life.

  Further, in the coaxial cable 10 according to the present embodiment, the second insulating layer 13 is provided on the outer periphery of the first insulating layer 12. The second insulating layer 13 is provided as a fixed layer of the shield layer 14. It is. Although the shield layer 14 is firmly adhered to the second insulating layer 13, the second insulating layer 13 and the first insulating layer 12 are not fixed (adhered). The insulating layer 12 can be easily peeled off manually without using a jig or the like.

  Therefore, the coaxial cable 10 according to the present embodiment can easily peel the second insulating layer 13 integrated with the shield layer 14 from the first insulating layer 12 when the terminal is connected. When connecting, the workability of the peeling work is improved.

  On the other hand, in the method for manufacturing the coaxial cable 10 according to the present embodiment, the shield layer 14 (Ag thin film) is formed by coating using a plating film method based on a silver mirror reaction. Therefore, in the conventional winding method, when a wire is wound, a problem such as deformation or bending of the wire is likely to occur. Therefore, there is a limitation on the formation speed of the shield layer, which is 1 m / min or less at the maximum. In the method for manufacturing the coaxial cable 10 according to the present embodiment, the formation speed of the shield layer 14 can be improved to 1.5 m / min or more. That is, the formation rate of the plating film by this silver mirror reaction is 1.5 times or more compared with the winding method, and several tens of times or more compared with the formation rate of the plating film by electroless plating, which is easy and good. The shield layer 14 can be coated with productivity.

  Further, the number of processes required for manufacturing the coaxial cable 10 according to the present embodiment is only the first insulating layer 12, the second insulating layer 13, the shield layer 14 by the manufacturing apparatus 30, and the covering process of the jacket 15. The coaxial cable 10 can be obtained in the manufacturing process. As a result, the manufacturing cost of the coaxial cable 10 according to the present embodiment can be reduced as compared with the coaxial cable described in Patent Document 2.

  As mentioned above, it cannot be overemphasized that embodiment of this invention is not limited to embodiment mentioned above, and various things are assumed in addition.

  Next, embodiments of the present invention will be described based on examples, but the embodiments of the present invention are not limited to these examples.

Example 1
As the central conductor, a twisted wire material in which seven strands of Cu-2 mass% Ag alloy wire having a strand diameter of 0.016 mm are twisted, and the outer periphery of the central conductor is configured with a PFA film having a thickness of 0.033 mm in order. A first insulating layer, a second insulating layer composed of a PET film having a thickness of 0.01 mm, a shield layer composed of an Ag thin film by a silver mirror reaction having a thickness of 2 μm (0.002 mm), and a thickness of 0.025 mm An ultrafine coaxial cable having an outer diameter of 0.188 mm was manufactured by covering a jacket made of a PFA film.

  Here, the Ag plating solution used for forming the Ag thin film by the silver mirror reaction is an Ag solution obtained by mixing 1 mol / l of ammonia water with 0.1 mol / l of an aqueous silver nitrate solution, and a reduction obtained by dissolving glucose in pure water. The solution was composed of a sex solution.

(Comparative Example 1)
A first insulating layer made of a PFA film having a thickness of 0.033 mm is coated on the outer periphery of the same central conductor as in the first embodiment. On the outer periphery of the first insulating layer, a Cu-0.2 mass% Sn-0.2 mass% In alloy wire having a strand diameter of 0.016 mm is horizontally wound to form a shield layer. The outer periphery of the shield layer was covered with a jacket made of a PFA film having a thickness of 0.025 mm, and an ultrafine coaxial cable having an outer diameter of 0.197 mm was manufactured.

  Compared with the coaxial cable of Comparative Example 1, the coaxial cable of Example 1 which is a coaxial cable according to the present invention was able to reduce the cable outer diameter by 4.5% or more.

  Further, in the coaxial cable of Example 1, although the shield layer was formed at a high speed of 1.5 m / min or higher, there were no problems such as cable bending and good bending characteristics were obtained. On the other hand, in the coaxial cable of Comparative Example 1, although the shield layer is formed at a low speed of 1.0 m / min or less, defects such as cable bending frequently occur and the cable is sufficiently bent. Characteristics were not obtained.

  Moreover, about the coaxial cable of Example 1, the 2nd insulating layer was able to be easily peeled from the 1st insulating layer by manual work, without using a jig | tool.

  The coaxial cable according to the present embodiment is suitable as a signal transmission and connection cable for medical devices such as diagnostic probes and endoscopes of ultrasonic diagnostic apparatuses, and information devices such as portable information terminals and notebook computers. Besides these, it can also be applied as a signal transmission cable for industrial robots and the like.

1 is a cross-sectional view of a coaxial cable according to a preferred embodiment of the present invention. It is a cross-sectional view of the cable core used for manufacture of the coaxial cable of FIG. It is the schematic of the shield coating apparatus used for manufacture of the coaxial cable which concerns on preferable one Embodiment of this invention. It is a cross-sectional view of a conventional coaxial cable.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Coaxial cable 11 Center conductor 12 1st insulating layer 13 2nd insulating layer 14 Shield layer

Claims (4)

In the coaxial cable having an insulating layer and a shield layer on the outer periphery of the center conductor, the center conductor is made of a single wire material using a Cu-2 mass% Ag alloy wire or a stranded wire material obtained by twisting a plurality of Cu-2 mass% Ag alloy wires. A first insulating layer composed of a PFA film having a thickness of 0.033 mm is provided on the outer periphery of the first insulating layer, and a second insulating layer composed of a PET film having a thickness of 0.01 mm is directly disposed on the outer periphery of the first insulating layer. A coaxial cable comprising: the shield layer formed of an Ag thin film having a thickness of 2 μm by silver mirror reaction on the outer periphery of the second insulating layer. In a coaxial cable manufacturing apparatus in which an insulating layer and a shield layer are provided on the outer periphery of a central conductor, a single wire material using a Cu-2 mass% Ag alloy wire or a stranded wire material obtained by twisting a plurality of Cu-2 mass% Ag alloy wires A first insulating layer composed of a PFA film having a thickness of 0.033 mm on the outer periphery of the central conductor and a second film composed of a PET film having a thickness of 0.01 mm directly on the outer periphery of the first insulating layer. Sending means for sending out a cable core provided with an insulating layer, surface treatment means for roughening the surface of the sent cable core, and cable core having a roughened surface provided after the surface treatment means A coaxial cable manufacturing apparatus comprising: a silver mirror reaction tank for forming an Ag thin film as the shield layer; and a winding means for winding the cable core covering the shield layer. The surface treatment means includes a surface roughening unit that roughens the surface of the cable core, and a degreasing / pickling bath that is provided after the surface roughening unit and degreases the cable core surface to perform acid cleaning. The apparatus for manufacturing a coaxial cable according to claim 2. In the manufacturing method of the coaxial cable which provides an insulating layer and a shield layer on the outer periphery of the center conductor, it is made of a single wire material using a Cu-2 mass% Ag alloy wire or a stranded wire material obtained by twisting a plurality of Cu-2 mass% Ag alloy wires. A first insulating layer made of a PFA film having a thickness of 0.033 mm is provided on the outer periphery of the central conductor, and a second made of a PET film having a thickness of 0.01 mm is directly provided on the outer periphery of the first insulating layer. An insulating layer is provided, and then the surface of the second insulating layer is roughened using the manufacturing apparatus according to claim 2, and then the outer periphery of the second insulating layer is formed from an Ag thin film using a silver mirror reaction. A method for manufacturing a coaxial cable, comprising providing the shield layer.

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