JPH0574169B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to flat cables used as internal wiring of electronic equipment such as computers, and more specifically, to flat cables used for 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.

[Conventional technology]

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 previously proposed a cable structure that satisfies these requirements. .

That is, 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 provided on the outermost periphery are arranged in parallel, and adjacent cores are fused and integrated.

The cable uses fluororesin as an insulator, so it has a low dielectric constant, and since it is made of foam, it has better electrical properties.The drain wire is in contact with the shield tape, so the terminal It has good processing workability, 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. That is, during this terminal processing, the jacket is removed using a cutting machine, and the shield tape is also removed at the same time.
If a highly foamed insulator is used with a higher degree of foaming to lower the dielectric constant, when the teeth of the cutting machine are inserted into the jacket, the soft foamed insulator will deform and the cutting machine will There was a drawback that the shield layer could not be peeled off at the same time as the jacket because it absorbed the force.

Furthermore, when the insulator is foamed to a high degree of foaming of 50% or more, there are air bubbles on the back side of the insulator, which causes electrical characteristics to change depending on the state of the air bubbles, resulting in unstable electrical characteristics.

The full fluororesin insulator layer is intended to solve these drawbacks.The presence of the full fluororesin insulator layer makes it possible to remove the jacket and shield layer all at once using a cutting machine.
Since the surface is smooth, the electrical characteristics are also stable.

[Problem that the invention seeks to solve]

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 a high frequency region are required.

FIG. 4 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 indicates the characteristic when the shielding tape layer of the cable core is provided by winding as shown in 5' in FIG. It shows the characteristics of a vertically installed one like 5''.

As is clear from their structure and characteristics, conventional flat cables provided with a shield layer by winding (characteristic B: see FIG. 5B for the core) have the disadvantage of large signal attenuation in the high frequency range. The reason for this is thought to be that the shield tape forming the shield layer is simply wound, resulting in poor stability and particularly poor signal attenuation in the high frequency range.

On the other hand, in a flat cable (characteristic C: see FIG. 5A for the core) in which a shield layer is provided vertically, the signal attenuation in the high frequency region is improved, but the problem is that the waveform is greatly disturbed. The reason for this is thought to be that the structure is such that the shield tape forming the shield layer is simply attached vertically, resulting in poor stability and disturbances in the waveform, especially in the high frequency range. It is thought that this is because the contact between the shield tape of the shield layer and the drain wire is not good and stable.

An object of the present invention is to eliminate the drawbacks of the prior art described 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. be.

[Means for solving problems]

The flat cable provided by the present invention comprises an insulated conductor consisting of a central conductor, a highly foamed fluororesin insulator layer coated on the outer periphery of the central conductor, and a solid fluororesin insulator layer coated on the outer periphery, and A drain wire attached vertically to at least one side of the conductor, a shielding tape layer attached longitudinally to the outer periphery of the drain wire, a pressing tape layer further wound around the outer periphery, and a thermoplastic coating extruded on the outermost periphery. A plurality of cores made of resin jackets are arranged in parallel, and only the surfaces of adjacent cores are thermally fused at least at predetermined intervals in the longitudinal direction,
The vertically attached shield tape layer is composed of a metal tape, a reinforcing polyester tape, and a laminate tape with a coating layer provided on the surface of the polyester tape, and a coating layer is provided on the tape surface of the presser tape layer. The present invention is characterized in that each of the coating layers is melted by the heat when the jacket is coated, so that the longitudinal shield tape layer, the pressing tape layer, and the jacket are fused and integrated.

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

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

The highly foamed fluororesin is PFA, FEP or E-TEF with a foaming degree of 50% or more, preferably 60% or more.
is provided by extrusion.

Fully fluororesins include PFA, FEP or E
-TFE is provided by extrusion, and this solid fluororesin layer may be extrusion coated simultaneously with the highly expanded fluororesin layer, or may be provided separately.

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, but the thicker the solid fluororesin layer, the more the dielectric This is not desirable because it increases the rate. The thickness of the full fluororesin insulator layer is preferably 0.10 mm or less, particularly preferably 0.06 mm or less, although it depends on the manufacturing technology.

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.

As a shield tape for the shield tape layer,
A laminate tape consisting of a metal tape such as a copper tape, a tin-plated copper tape, or an aluminum tape, a polyester tape, and a coating layer of a vinyl-based resin is used, and the metal tape side is used on the inside.

As a presser tape on the shield tape layer,
Polyester tape is used, and the surface of the tape is coated with vinyl resin.

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

When using aluminum tape as the metal tape, the tape thickness is about 25 to 10 μm.
The polyester tape is for reinforcing the metal tape, and is preferably 6μ or less, preferably 4μ or less.
That is, the thicker the polyester tape, the higher its strength and the easier it is to handle during manufacturing, but if it is too thick, the shield tape cannot be peeled off at the same time as the jacket during terminal treatment.
According to experiments, when the polyester tape was 25μ thick, it could not be peeled off at all, and when the thickness was 12μ, only a portion could be peeled off. On the contrary,
If the thickness is 6μ or less, 100% peeling is possible, so it is preferable to use a polyester tape with a thickness of 6μ or less, preferably 4μ.

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-adhesive. That is, when fusing the core, only the upper and lower surfaces are heat-sealed by heating the jacket to a temperature higher than the melting point of the thermoplastic resin used for the heat-sealing.
The volume of the jacket changes significantly, making it impossible to obtain consistent dimensional accuracy between the center conductors.To prevent this, only the upper and lower surfaces are partially heat-sealed.

[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.

FIG. 1 shows a core of a flat cable, and FIG. 2 shows a flat cable made up of a plurality of cores. In these drawings, reference numeral 1 denotes a central conductor, and a highly foamed insulator and a solid insulator 3 are sequentially provided on the outer periphery of the central conductor 1, thereby forming an insulated conductor 8. Reference numeral 4 denotes a drain wire that is vertically attached to the insulated conductor 8, and a vertically attached shield tape layer 5 is further provided on the outer periphery of these drain wires by longitudinally attaching a shield tape. Reference numeral 6 denotes a press-wound polyester tape layer formed on the vertically attached shield tape layer 5 by winding a polyester tape. Reference numeral 7 denotes a jacket provided on the outermost periphery, and the core 9 is constructed using the jacket 7 as a surface layer.

Here, as the center conductor 1 and the drain wire 4, a silver-plated annealed copper wire with an outer diameter of 0.254 mm is used. Highly foamed insulation 2 has a foaming degree of 60% or more.
PFA is used and the outer diameter is 0.57 mm by extrusion. The solid insulator 3 has E
-TFE is used and its thickness is approximately 0.05mm.

As the vertical shielding tape layer 5, a laminated tape of polyester tape and aluminum tape is used, and the thickness is 20μ in the case of aluminum tape and 4μ in case of polyester tape, and the surface of the polyester tape is thinly coated with vinyl-based resin. It is made of laminated tape.

In addition, as the pressing tape layer 6 formed by wrapping the tape over the vertically attached shield tape layer 5, a polyester tape with a thickness of 6 μm is used.
Both sides of the polyester tape are thinly coated with 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±.
It is formed to be 0.1 (mm).

The core 8 of the cable thus formed is the second
As shown in the figure, a plurality of cores are arranged in parallel, and only the surfaces of adjacent cores are integrated by heat fusion.

According to the flat cable of this embodiment formed as described above, characteristic impedance: Z ₀ =55±5
(Ω), transmission speed: T _d = 3.9±0.1 (nsec/m), and the distance between conductors was 10.27±0.7 (mm).
is maintained.

Figure 3 shows an example of a device for measuring the electrical characteristics of the cable of this example.Measurement samples:
The transmittance is measured when a signal input from one end of a flat cable is output from the other end, and the measurement results are shown in FIG.

In Fig. 4, characteristic A was obtained with the flat cable of this example, in which the shield layer in the core structure is a vertically-supported shield tape layer as shown in 5 in Fig. 5A, and is pressed from above. A rolled tape layer 6 is applied. Characteristic B is due to the conventional flat cable, and the shield layer in the core is simply wrapped with shield tape as shown at 5' in FIG. 5B. Furthermore, characteristic C is also due to the conventional flat cable, and the shield layer in the core is shown in Figure 5C.
This is simply a matter of vertically attaching the shielding tape as shown in the 5''.

As is clear from these characteristics, the characteristic A obtained by the flat cable of this embodiment causes significantly less signal attenuation in the high frequency range than the characteristic B obtained by simply wrapping the conventional shield tape. This is proven by the fact that the signal attenuation is improved even if the shielding tape is simply applied vertically as in characteristic C. This proves that the contact between the drain wire and the shield tape of the vertically attached shield tape layer is good and stable. Furthermore, it can be seen that the waveform disturbance is extremely reduced compared to characteristic C where the shield tape is simply attached vertically. In particular, waveform disturbances in the high frequency region will become a more problematic element as electronic devices such as computers become faster in the future, and the characteristic A according to the present invention is optimal in this respect.

〔Effect of the invention〕

As explained above, the flat cable of the present invention has excellent electrical properties, especially in the high frequency range, with less signal attenuation and less waveform disturbance. By integrating the vertical shield layer and the vertical shield layer, it is possible to strip them all at once, which in turn improves terminal processing performance. It has great utility as a wiring cable.

[Brief explanation of drawings]

FIG. 1 is an explanatory cross-sectional view showing one embodiment of the core constituting the flat cable of the present invention, FIG. 2 is an explanatory cross-sectional view showing one embodiment of the flat cable of the present invention, and FIG. An explanatory diagram showing an example of a device for measuring the electrical characteristics of a flat cable, FIG. 4 is a characteristic diagram comparing the characteristics of the cable of the present invention and a conventional cable measured by the device shown above, and FIG. is an explanatory diagram showing the core of a flat cable in an easy-to-understand manner;
C shows a conventional cable core. In the symbols, 1 is the center conductor, 2 is the layer of highly foamed fluororesin insulation, 3 is the layer of solid fluororesin insulation,
4 is a drain wire, 5 is a vertically attached shield tape layer, 6 is a shield pressing tape layer, 7 is a vinyl jacket, 8 is an insulated conductor, and 9 is a core.

Claims (1)

[Claims] 1. An insulated conductor consisting of a central conductor, a highly foamed fluororesin insulator layer coated on its outer periphery by extrusion, and a solid fluororesin insulator layer coated on its outer periphery, and an insulated conductor that is longitudinally attached to at least one side of the insulated conductor. A plurality of cores each consisting of a drain wire, a shielding tape layer vertically attached to the outer periphery of the drain wire, a pressing tape layer wound around the outer periphery of the drain wire, and a thermoplastic resin jacket extruded and coated on the outermost periphery. The vertically attached shield tape layer consists of a metal tape, a reinforcing polyester tape, and a surface of the polyester tape. Furthermore, a coating layer is provided on the tape surface of the press-wound tape layer, and each of the coating layers is melted by the heat when covering the jacket, and the longitudinally applied shield tape layer is A flat cable characterized in that the pressure tape layer and the jacket are fused and integrated.