JPH0414809Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the improvement of shielded cables, particularly low-noise shielded cables.

[Prior Art] Many shielded cables for signal transmission are used as internal wiring of electronic devices.

Conventional shielded cables of this type consist of a conductor, an insulator layer, a shield layer, and a shield layer provided sequentially around the conductor.
and a jacket layer.

However, with conventional shielded cables, the mV between the conductor and the shield is
When it becomes larger than μV, it has the disadvantage of poor transmission characteristics due to low frequency noise on the order of several +V.

To address this drawback, a so-called low-noise shielded cable has already been proposed in which low-frequency noise is reduced by providing a conductive paint on the outer periphery of the insulating layer.

[Problems to be solved by the invention] By the way, in conventional low-noise cables of this type, the most effective way to reduce noise is to apply conductive paint between the insulator and the shield, as mentioned above. However, in order to maximize its effectiveness, strong adhesion to the insulator is necessary.

However, if the adhesion between the paint and the insulator is strong, there is a drawback that the end workability is reduced and the cost required for peeling the paint increases.

In other words, the adhesion between the conductive paint and the insulator is
They have contradictory characteristics, and therefore one of the requirements must be sacrificed, and it has been desired to provide a low-noise shielded cable that satisfies both characteristics.

On the other hand, as a characteristic required of this low-noise shielded cable, when the shielded cable is used for signal transmission, a low dielectric constant is particularly desired as an insulator.

Furthermore, in order to achieve low noise, it is necessary to perform a shielding process on the terminal, and it is also necessary to withstand the heat of the solder during this process, so it is desirable to use an insulator with heat resistance.

An insulator that satisfies this requirement is TFE (4
fluorinated ethylene), ETFE (ethylene tetrafluorinated ethylene copolymer), FEP (fluorinated ethylene propylene),
Fluororesins such as PFA (Perfluoroalkoxy) are preferred.

However, fluororesin has poor adhesion to conductive paint and cannot be said to have the maximum noise reduction effect.

Polyethylene, vinyl chloride, polypropylene, etc. are excellent in terms of adhesion to conductive paints, but they are inferior to fluororesins in terms of low dielectric constant and heat resistance.

[Means for Solving the Problems] The purpose of the present invention is to eliminate the drawbacks of the prior art described above, to have an insulator with good heat resistance, low dielectric constant, and strong adhesion to paint, and to An object of the present invention is to provide an improved low-noise shielded cable with excellent workability.

That is, the gist of the present invention is to provide a conductor, a first insulating layer made of a fluororesin sequentially provided around its outer periphery, a second insulator layer having strong adhesion to the fluororesin, and a second insulator layer having strong adhesion to the fluororesin. The present invention provides a low-noise shielded cable comprising a conductive paint layer having good compatibility with a second insulating layer, a shield layer, and a jacket layer.

[Example] Next, an example of the low-noise shielded cable of the present invention will be further described with reference to the accompanying drawings.

In the attached drawings, 1 is a conductor, and a fluororesin insulator layer 2, an insulator layer 3 with strong adhesion to the fluororesin, a conductive paint 4, a shield layer 5, and a jacket layer 6 are sequentially provided on the outer periphery of the conductor. It is being

Here, as the fluororesin insulator layer 2, TFE,
Fluororesins such as ETFE, FEP, and PFA are preferred;
For example, FEP has a heat resistance of 200°C, is flexible, and has a dielectric constant of 2.1, making it a good transmission material.

However, FEP has low adhesion to the conductive paint 4.

Therefore, as the second insulator layer, an insulator 3 having strong adhesion to the fluororesin is used to improve the adhesion between the conductive paint 4 and the insulator 3.

Polyethylene, vinyl chloride, polypropylene, etc. are used as the insulating layer 3 that has strong adhesion to the fluororesin.

Although it is preferable for the second insulator layer 3 to be relatively thinner than the first insulator layer 2 from the viewpoint of cable characteristics, it is necessary to have a thickness that does not reduce the terminal processability. .

That is, by peeling off the second insulating layer 3 and the conductive layer 4 all at once, the conductive layer 4 has the property of being able to peel off the insulator while maintaining its strong adhesion, making terminal processing very easy. This is because.

As the conductive paint 4, polyethylene or a polyethylene component-based conductive paint, or vinyl chloride or a vinyl chloride component-based conductive paint is used together with the second insulating layer 3, and the thickness of the paint is approximately
It is about 0.02 to 5 mm.

As the shield layer 5, a horizontally wound shield, a braided shield, etc. are preferable.

Note that a foamed type fluororesin can also be used as the fluororesin for the first insulator layer 2, and in this case, since it is covered with the second insulator, the conductive paint will not enter.

The shielded cable constructed in this manner has excellent heat resistance because the FEP maintains the insulation between the conductor 1 and the shield 5 when the shield 5 is connected by soldering.

[Effects of the invention] The invention as described above has an insulator with good heat resistance, low dielectric constant, and strong adhesion to paint, and has improved low noise with excellent terminal processability. This makes it possible to provide shielded cables, and its practical value is extremely great.

[Brief explanation of the drawing]

The accompanying drawing is an explanatory diagram showing an embodiment of the low-noise shielded cable of the present invention. 1... Conductor, 2... Fluororesin insulator, 3... Insulator layer with strong adhesion to fluororesin, 4... Conductive paint with good compatibility with the insulator layer, 5... Shield layer, 6...jacket.

Claims (1)

[Scope of utility model registration request] A conductor, a first insulating layer made of a fluororesin sequentially provided around the conductor, a second insulator layer having strong adhesion to the fluororesin, and having good compatibility with the second insulator layer. A low-noise shielded cable comprising a conductive paint layer, a shield layer, and a jacket layer.