JPH0580766B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to flat cables used as internal wiring of electronic devices such as computers, and more specifically, to the ease of wiring work, electrical characteristics, and terminal processing workability. It concerns an excellent flat cable.

[Prior Art] Internal wiring materials for electronic devices such as computers are required to have characteristics such as wiring workability, electrical properties, and terminal processing workability, and the applicant has developed a method to satisfy these requirements. We have previously proposed two cable structures.

In other words, this cable consists of an insulated conductor consisting of a central conductor, a highly foamed fluororesin insulator provided around its outer periphery, and a solid fluororesin insulator layer coated on the outer periphery, and a drain wire attached vertically to the insulated conductor. , a plurality of cable cores each consisting of a shield tape layer provided on the outer periphery and a thermoplastic resin jacket layer provided on the outermost periphery are arranged in parallel, and adjacent cores are fused and integrated.

This cable uses fluororesin as an insulator, so it has a low dielectric constant, and since it is made of foam, it has even better electrical properties.The drain wire is in contact with the shield tape, so the cable is terminally processed. It is easy to work with, and since the core is flat, wiring work is easy and has achieved the desired results.

The reason why a solid fluororesin insulator layer is provided as an insulator around the outer periphery of the highly expanded fluororesin insulator layer is as follows.

In other words, when processing the terminals of this cable, the jacket is removed using a cutting machine and the shielding tape is also removed at the same time.In order to further lower the dielectric constant, the insulation is made of highly foamed insulators with increased degree of foaming. In this case, when the teeth of the cutting machine are inserted into the jacket, the soft foam insulation deforms and absorbs the force of the cutting machine, making it difficult to peel off the shield layer at the same time as the jacket. .

Furthermore, when the insulator is foamed to a high degree of foaming of 50% or more, air bubbles are present on the surface of the insulator, and the electric characteristics change depending on the state of the air bubbles, which has the disadvantage that the electric characteristics are unstable.

The solid fluororesin insulation layer is intended to solve these drawbacks.The presence of the solid fluororesin insulation layer allows the jacket and shield layer to be removed all at once using a cutting machine, and the surface becomes smooth. Therefore, the electrical characteristics are also stable.

[Problems to be Solved by the Invention] Incidentally, in recent years, electronic devices such as computers have been trending toward higher speeds, and in this case, waveform stability and characteristics with less signal attenuation in the high frequency region are required. become.

FIG. 5 shows the transmittance characteristics of the flat cable with respect to frequency, and B and C show the characteristics of the flat cable previously proposed by the applicant.

Here, characteristic B is a case in which the shield tape layer is provided by winding, and characteristic C is a case in which the shield tape is provided by vertically attaching.

As is clear from this figure, the conventional flat cable (characteristic B) provided with a shield layer by winding had the drawback of large signal attenuation in the high frequency range.

This is due to the fact that the shield tape is simply wound.

On the other hand, the structure in which the shield layer is provided vertically (characteristic C) improves signal attenuation in the high frequency region, but has the drawback of large waveform disturbance.

The reason for this is also considered to be that the structure is such that the shield tape is simply attached vertically, resulting in poor stability and disturbances in the waveform, especially in the high frequency range.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art mentioned above, and to provide a flat cable for electronic equipment that has good wiring workability, good terminal processing workability, and excellent electrical characteristics, especially in the high frequency range. .

[Means for solving the problem] In other words, the gist is: a central conductor, a highly foamed fluororesin insulator layer coated on the outer periphery by extrusion, and a solid fluororesin insulator layer coated on the outer periphery. an insulated conductor consisting of; a drain wire attached vertically to at least one side of the insulated conductor;
A plurality of cores are arranged in parallel, each consisting of a shielding tape layer vertically attached to the outer periphery, a pressing tape layer further wound around the outer periphery, and a thermoplastic resin jacket coated by extrusion on the outermost periphery. The shield tape is made by heat-sealing only the surfaces of adjacent cores at least at predetermined intervals in the longitudinal direction, and the shield tape is made of a metal tape, a reinforcing polyester tape, and a coating layer provided on the surface of the polyester tape. It is a laminated tape, and the polyester tape has independent holes uniformly provided in the vertical and horizontal directions of the tape, and the press-wound tape has a coating layer on both sides, and furthermore, the tape has a coating layer on both sides. Independent holes are uniformly provided in the lateral direction, and each of the coating layers is configured to be melted by the heat when covering the jacket, so that the shield tape, the presser tape, and the jacket are fused and integrated. It is located on a flat cable.

In the above, a silver-plated annealed copper wire is used as the center conductor.

That is, the flat cable of the present invention uses a fluororesin as an insulator, and is silver-plated to prevent the conductor from discoloring at the high temperatures during extrusion of the fluororesin.

The highly foamed fluororesin layer has a foaming degree of 50% or more,
Preferably 60% or more PFA, FEP, or E-
TFE is provided by extrusion.

The solid fluororesin layer is provided by extrusion of PFA, FEP, or E-TFE, and this solid fluororesin layer may be extruded and coated simultaneously with the highly expanded fluororesin layer, or may be provided separately. It is something.

Here, the solid fluororesin insulator layer must be provided sufficiently thinner than the foamed fluororesin insulator layer.

In other words, the solid fluororesin insulator layer is good for the purpose of stabilizing the electrical characteristics if it covers the surface of the foam insulator layer to make the surface smooth.
Increasing the thickness of the solid fluororesin layer is not preferable because the dielectric constant increases accordingly.

Although this thickness depends on the manufacturing technology, it is preferably 0.10 mm or less, particularly preferably 0.06 mm or less.

The drain wire may be provided on at least one side of the insulated conductor, and may be provided on both sides of the insulated conductor if necessary.

The shielding tape used is copper tape, tin-plated copper tape, or metal tape such as aluminum tape, polyester tape with uniform independent holes, and laminate tape with a coating layer of vinyl-based resin. It is used with the metal tape side facing inside.

As the presser tape on the shield tape, a polyester tape with uniformly provided independent holes is used, and both sides of the tape are coated with vinyl resin.

The coating layer provided on the surface of the polyester tape for shielding and presser winding is melted by the heat during coating the jacket, and the shield tape, presser tape, and jacket are all fused and integrated.

When using aluminum tape as the metal tape, one with a thickness of about 10μ is used.

Polyester tape is used for reinforcing metal and for wrapping on shield tape, preferably 6μ or less, preferably 4μ or less,
The tape used has independent holes drilled uniformly and continuously in the vertical and horizontal directions, and has a low tensile strength to the extent that there is no problem in the tape application work and the tape wrapping work. In other words, the thicker the polyester tape without holes, the stronger it is and the easier it is to handle during manufacturing. However, if the tape is too strong, the shield may peel off at the same time as the jacket during terminal processing. This is because it is not possible.

According to experiments, when the polyester thickness is 25μ,
It was not possible to remove it at all, and when it was 12μ, only a portion of it could be removed.

On the other hand, those with uniform and continuous independent holes of 6μ or less and reduced tensile strength
It is 100% removable, and in this application a polyester tape with uniform, continuous, independent holes of a thickness of 6 microns or less, preferably 4 microns, is used.

The jacket is provided by extrusion coating of thermoplastic resin.

As a method for heat-sealing the cores arranged in parallel, it is preferable that only the upper and lower surfaces of the cores be heat-sealed, and the contact portions between adjacent cores be non-sealed.

In other words, when fusing the core, only the top and bottom surfaces are heated to a temperature above the melting point of the jacket, but at this time, the volume of the jacket changes significantly and the dimensional accuracy between the center conductors is affected. In order to prevent this, it is preferable to heat-seal only the upper and lower surfaces.

[Embodiments of the Invention] Next, an embodiment of the flat cable of the present invention will be further described with reference to the accompanying drawings.

In FIG. 1, 1 is a central conductor, and a foamed insulator 2 and a solid insulator 3 are sequentially provided on the outer periphery of the central conductor, forming an insulated conductor.

Reference numeral 4 denotes a drain wire attached vertically to the insulated conductor, and a shielding tape 5 is further attached longitudinally to the outer periphery of the drain wire.

6 is a press-wound polyester tape layer applied from above the vertically spliced shield tape.

7 is a jacket provided on the outermost periphery of these, and constitutes a cable core.

Here, as the center conductor 1 and the drain wire 4, a silver-plated annealed copper wire with a diameter of 0.254 mm is used.

The foamed insulator 2 is made of PFA with a foaming degree of 60% or more, and is extruded to have an outer diameter of about 0.57 mm.

E-TFE is used as the solid insulator 3,
Its thickness is about 0.05mm.

As the shield tape 5, a laminate tape of polyester and aluminum is used.
The tape is 10μ thick, the polyester is 4μ thick, and as shown in Figure 3, a tape with uniform, continuous, independent holes is used, and the polyester surface is thinly coated with vinyl resin. is used.

In addition, as the pressing tape 6 from above the shield, a polyester tape having a thickness of 4μ and having uniformly continuous and independent holes as shown in Fig. 3 is used, and both sides of the polyester are , coated with a thin layer of vinyl resin.

Jacket 7 is made of extruded vinyl and has a width of 1.27±0.07 (mm) and a thickness of 1.20±0.1 (mm).
It is set in.

A plurality of cable cores formed in this manner are arranged in parallel as shown in FIG. 2, and only the surfaces of adjacent cores are integrated by fusion.

According to the flat cable of this embodiment constructed in this way, the characteristic impedance Z ₀ =55±5(Ω),
A characteristic of transmission speed Td = 3.9±0.1 (nsec/m) was obtained, and the distance between conductors was maintained at 1.27±0.07 (mm).

Fig. 4 shows an example of a device for measuring the electrical characteristics of the cable of this embodiment, which measures the transmittance in which a signal input from one end of the measurement sample is output from the other end. represents the measurement results.

As is clear from FIG. 5, the cable of this embodiment (characteristic A) exhibits extremely less signal attenuation in the high frequency range than the conventional cable wrapped with shield tape (characteristic B).

This has a structure in which tape is wrapped around the vertically attached shield, and it proves that the contact between the shield tape and the drain wire is good. ), it can be seen that the waveform disturbance is extremely small.

In particular, waveform disturbance in the high frequency region will become a problem if electronic equipment such as computers becomes faster in the future, and it is clear that the product of the present invention has good characteristics.

[Effects of the Invention] As explained above, according to the present invention, it is possible to provide a cable for internal wiring of electronic equipment which has excellent electrical properties particularly in the high frequency range and excellent terminal processing workability, It has tremendous value.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view showing one embodiment of the core constituting the flat cable of the present invention, FIG. A schematic explanatory diagram showing an example of a polyester tape applied to a flat cable, FIG. 4 is an explanatory diagram showing an example of an apparatus for measuring the electrical characteristics of the cable of the present invention, and FIG. FIG. 3 is a characteristic diagram comparing the characteristics of conventional cables. 1: Conductor, 2: Highly foamed fluororesin insulator layer, 3:
Full fluororesin insulator layer, 4: Drain wire, 5:
Vertical shield tape layer, 6: Shield presser tape layer, 7: Vinyl jacket layer.

Claims (1)

[Claims] 1. An insulated conductor consisting of a central conductor, a highly foamed fluororesin insulation layer coated on the outer periphery by extrusion, and a solid fluororesin insulation layer coated on the outer periphery, and an insulated conductor that is longitudinally attached to at least one side of the insulated conductor. A core consisting of drain wires, a shielding tape layer longitudinally attached to their outer peripheries, a pressing tape layer wound around the outer peripheries, and a thermoplastic resin jacket extruded and coated on the outermost periphery. A plurality of shield tapes are arranged in parallel, and only the surfaces of adjacent cores are thermally fused at least at predetermined intervals in the longitudinal direction, and the shield tape is a metal tape, a reinforcing polyester tape, and a surface of the polyester tape. The polyester tape is a laminated tape with a coating layer, and the polyester tape has independent holes uniformly provided in the vertical and horizontal directions of the tape, and the press-wound tape has coating layers on both sides, and the tape Independent holes are uniformly provided in the vertical and horizontal directions,
The flat cable is characterized in that each of the coating layers is melted by heat when covering the jacket, so that the shield tape, the presser tape, and the jacket are fused and integrated.