JP4137255B2 - coaxial cable - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coaxial cable used as a signal transmission line of a high-frequency component such as a measuring device, an information communication device, or an information processing device that requires particularly excellent high-frequency characteristics.
[0002]
[Prior art]
In recent years, measuring devices and information communication devices have been further reduced in size, and accordingly, coaxial cables used have been required to have a smaller diameter.
Therefore, instead of the conventional metal braided layer, the surface of the insulator is subjected to surface modification such as chemical treatment so that the metal plating is likely to adhere, and then a metal plating layer or a metal vapor deposition layer is provided on the surface of the insulator. A coaxial cable realizing a diameter has been known (for example, Japanese Utility Model Laid-Open No. 62-33117).
However, as in the above example, when a fluororesin with low dielectric loss and excellent high-frequency characteristics is used as the insulator of the coaxial cable, the metal layer is difficult to adhere and the metal layer thickness becomes uneven. In addition, there is a problem in quality that the adhesion between the insulator and the metal layer is weak and inferior in durability.
Furthermore, in order to improve adhesion (adhesiveness) to the insulator and facilitate terminal peeling, a resin that is more easily electrolessly plated than the insulator is extruded or tape-wrapped between the insulator and the plating layer. A coaxial cable is also known (for example, JP-A-7-272553).
However, even in this method, it is difficult to reduce the diameter because the insulating layer is thick, and because it is coated with a resin that is easily electroless-plated, which has an electrical characteristic different from that of the insulator, the high-frequency characteristics are affected. There is a problem of getting out.
[0003]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-described problems of the prior art, to provide a coaxial cable that is excellent in plating adhesion, compact, and excellent in high-frequency characteristics.
[0004]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have a thin ABS resin that has good adhesion to both the modified surface of the insulator and the plating layer and does not affect the high frequency characteristics. The present invention has been completed with the idea of providing a coating layer between the insulator and the electroless plating layer.
[0005]
That is, the present invention is an insulating material comprising a fluororesin having a wall thickness of 0.035 mm or more extruded and coated on a single wire or stranded wire conductor having an outer diameter of 0.03 mm or more and having an uneven surface formed by excimer laser treatment or chemical treatment. Body, an ABS resin coating layer having a thickness of 0.05 μm to 3 μm applied on the insulator, an electroless metal plating layer having a thickness of 0.5 μm to 5 μm on the ABS resin coating layer, and the electroless metal plating layer The coaxial cable is characterized in that an electrolytic metal plating layer having a thickness of 5 μm or more is provided, and the outermost layer is formed of a protective coating layer.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings.
In FIG. 1, 1 is a conductor, 2 is an insulator, 3 is an ABS resin coating layer, 4 is an electroless plating layer, 5 is an electrolytic plating layer, and 6 is a protective coating layer.
As the conductor 1, a single wire or stranded wire conductor such as a silver-plated tin-containing copper alloy wire or a copper-coated steel wire having an outer diameter of 0.03 mm or more is used.
Examples of the insulator 2 include ethylene tetrafluoride resin (PTFE), ethylene tetrafluoride-perfluoroalkyl vinyl ether copolymer resin (PFA), tetrafluoroethylene-hexafluoropropylene copolymer resin (FEP), four A fluororesin such as fluorinated ethylene-ethylene copolymer resin (ETFE) is used, but among the fluororesins, tetrafluoroethylene-hexafluoropropylene copolymer resin (FEP) having particularly low dielectric loss is particularly preferable. The wall thickness of the insulator 2 is 0.035 mm or more.
Next, the outer periphery of the insulator 2 is subjected to a metal sodium-naphthalene-based or metal sodium-ammonia-based chemical treatment, or surface modification treatment using an excimer laser or the like.
Next, an ABS resin coating layer 3 having a film thickness of 1 μm to 3 μm is applied to the outer periphery of the insulator 2 that has been subjected to the surface modification treatment. The coating layer 3 is formed by dipping or applying to an ABS resin tank dissolved in a solvent.
[0007]
Here, the ABS resin coating layer 3 is a very thin film having a film thickness of 0.05 μm to 3 μm, and has been surface-modified and bites into the surface of the insulator on which the irregularities are formed. Strong adhesion is obtained.
Furthermore, since the ABS resin has good adhesion to the plating in the next process, providing this ABS resin coating layer between the surface-modified insulator and the plating layer makes the plating more durable than the conventional method. Greatly improved.
Here, since the film thickness of the coating layer 3 of the ABS resin is as thin as 3 μm or less, excellent high frequency characteristics can be expected without affecting the high frequency characteristics.
Next, electroless plating is performed on the surface of the ABS resin coating layer 3. As the electroless plating layer 4, a copper plating layer having a thickness of 0.5 μm to 5 μm is provided. Furthermore, an electrolytic plating layer 5 is provided on the outer periphery of the electroless plating layer 4. As the electrolytic plating layer 5, a copper plating layer having a thickness of 5 μm to 30 μm is provided. Examples of the copper plating include copper cyanide plating and copper sulfate plating. In the present invention, copper sulfate having good spreadability and strong bending is selected.
Finally, a protective coating layer 6 having a thickness of 0.02 mm or more is provided on the outer periphery of the electrolytic plating layer 5. As the protective coating layer 6, various coating materials such as PVC, polyethylene, and polyurethane can be selected.
[0008]
【Example】
As the conductor 1, a silver-plated single wire of 0.3% tin-containing copper alloy having an outer diameter of 0.05 mm was used. The insulator 2 was extrusion coated with tetrafluoroethylene-hexafluoropropylene copolymer resin (FEP) to a thickness of 0.05 mm.
Next, before the plating process, the surface and outer periphery of the insulator 2 were surface-modified with a KrF excimer laser having a wavelength of 248 nm.
Next, ABS resin was applied in a thickness of 1 μm to the outer periphery of the insulator 2 subjected to surface modification. Furthermore, the thickness of the electroless plating on the ABS resin coating was 3 μm, and the thickness of the electrolytic plating was 27 μm.
Finally, polyethylene was coated and coated as a protective coating layer, and the thickness was 0.035 mm.
As described above, a thin coaxial cable having an outer diameter of 0.28 mm, which is difficult with metal braiding, can be easily produced.
Moreover, the high frequency characteristics were equivalent to those of the conventional coaxial cable.
[0009]
【The invention's effect】
In the coaxial cable of the present invention, the adhesion of plating can be increased by interposing an ABS resin coating layer between the surface-modified insulator and the plating layer, and the durability of plating can be improved.
Further, the ABS resin coating layer is a very thin layer, and does not affect the high frequency characteristics, so that excellent high frequency characteristics can be obtained.
Furthermore, since the metal braid is not used and the metal plating layer is used, the diameter of the coaxial cable can be reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a coaxial cable of the present invention.
[Explanation of symbols]
1 Conductor 2 Insulator (Fluororesin)
3 ABS resin coating layer 4 Electroless plating layer 5 Electrolytic plating layer 6 Protective coating layer

Claims (1)

An insulator made of a fluororesin having a wall thickness of 0.035 mm or more extruded and coated on a single wire or stranded wire conductor having an outer diameter of 0.03 mm or more, and having an uneven surface formed by excimer laser treatment or chemical treatment on the insulator An ABS resin coating layer having a thickness of 0.05 μm to 3 μm applied to the substrate, an electroless metal plating layer having a thickness of 0.5 μm to 5 μm on the ABS resin coating layer, and a thickness of 5 μm or more on the electroless metal plating layer A coaxial cable, wherein an electrolytic metal plating layer is provided, and the outermost layer is formed of a protective coating layer.

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