JPH0582684B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a parallel coaxial core flat cable that is used as internal wiring of electronic equipment and is particularly useful for high-speed signal transmission. A flatket cable with this structure consists of an extruded foamed fluororesin insulator on the outer periphery of the conductor, an insulated conductor formed by sequentially applying a skin layer, a drain wire attached to this insulated conductor, and the insulated conductor and drain wire covered all at once. A coaxial core is used which includes a shielding tape winding layer and a fluororesin jacket which is covered by extrusion on the outer periphery of the shielding tape winding layer and has a rectangular outer shape. It consists of two pieces bonded together by heat fusion.

[Conventional technology]

In recent years, there has been an increasing demand for cables used for internal wiring of electronic equipment such as computers to save space within the equipment and to transmit signals at high speed.

Therefore, this type of cable uses a coaxial core and a flat cable with many coaxial cores arranged in parallel.The insulator of the coaxial core is a fluororesin with a low dielectric constant, especially a high foaming rate of 70% or more. The use of foamed fluororesin is being considered. This flat cable has coaxial cores arranged in parallel so that the pitch between signal lines is 1.27 mm.

[Problem that the invention seeks to solve]

In the above-mentioned coaxial core parallel type flat cable, the insulated conductor of each coaxial core is coated with a highly foamed fluororesin insulator by extrusion, and the conductor has an ultra-thin diameter of 0.26φ or less, and the highly expanded fluororesin insulator has a diameter of 0.3mm or less.
Ultra-thin wall thickness of less than mm. However, it is necessary to achieve ultra-high foaming with a high foaming rate of 70% or more in the ultra-thin insulator, but such ultra-thin and ultra-high foaming fluororesin insulators become extremely soft. , the adhesion strength to the conductor is also weakened.
This causes a problem in that the force with which the conductor is held down by the insulator becomes weak. Furthermore, since the conductor was a single wire of tin-plated annealed copper, the adhesion strength of the insulator was extremely weakened, which resulted in the disadvantage that the conductor could move during terminal processing.

Therefore, in the past, special jigs and tools were used to maintain the specified dimensions constant, but these were inefficient and required many man-hours for terminal processing, making them expensive.

Generally, if the above-mentioned problem occurs when the conductor is a single wire, it is considered to use a twisted wire.
It is true that when using stranded wires, even if the insulation is thin, highly foamed, and soft, the apparent adhesion strength of the insulation to the insulation is improved compared to the case of solid wires due to the unevenness on the surface of the strands. This solves the problem of the conductor moving during the terminal processing process.

However, on the other hand, the measures taken by twisted wires are to prevent the twisted wires from coming apart when soldering to the board.
Therefore, preliminary soldering is required in advance, resulting in an inefficient and very expensive terminal processing operation, which is a drawback depending on the intended use and the terminal processing method.

In order to solve the above-mentioned problems of the prior art, the present invention provides a foaming ratio as an insulated conductor in a coaxial core.
While using stranded wire as a conductor under the condition that a highly expanded fluororesin insulation of 70% or more is applied by extrusion,
It is an object of the present invention to provide a novel coaxial core parallel flat cable of this type, which does not require prior pre-soldering as stranded wires.

[Means and actions to solve the problem]

In the coaxial core parallel flat cable provided by the present invention, the insulated conductor of each coaxial core has a rod-shaped stranded wire conductor 3 and a foaming ratio of 70% or more that is extruded and coated on the outer periphery of the stranded wire conductor 3, as shown in the attached drawing. The rod-shaped stranded wire conductor is made of a highly foamed fluororesin insulator 4.
By making a stranded wire using tin-containing copper alloy strands 1 having a silver plating layer, and applying a temperature high enough to melt the silver plating layer, the contact portions of adjacent tin-containing copper alloy strands are It is characterized in that it is joined by a silver plating fused part 2.

In the above, the reason why the tin-containing copper alloy wire 1 having a silver plating layer is used for the stranded wire is that the outer diameter of the conductor used in this type of cable is as small as 0.26φ or less, and it is formed by stranded wire. This is to ensure that the ultra-fine stranded wire retains its tensile strength so that it will not break due to working tension when it is heated to about 400°C, the temperature at which the silver plating layer melts in the subsequent process. Furthermore, the purpose of providing the silver plating layer is to prevent the fluororesin from melting at high temperatures when it is extruded and coated on the outer periphery of the conductor. Incidentally, the tin plating, solder plating, etc. used in conventional conductors melts due to the high temperature heat generated when extruding the fluororesin.

The present invention is characterized in that, in a stranded wire using tin-containing copper alloy strands 1 having a silver plating layer as described above, a temperature sufficient to melt the silver plating layer of each tin-containing copper alloy strand is applied. Therefore, by forming silver-plated fused parts 2 only on the contact parts of adjacent tin-containing copper alloy strands to bond the strands, it is possible to make the stranded wire into a rod-like shape while also improving the surface unevenness of the stranded wire. This makes it possible to share both the "prevention of unraveling" of the stranded wires and the "strengthening" of the highly foamed fluororesin insulator by extrusion.

[Embodiment] Figs. 1 to 3 show an embodiment of the coaxial core parallel type flat cable of the present invention, Fig. 1 shows the conductor of the coaxial core, Fig. 2 shows the coaxial core,
Figure 3 shows a flat cable.

As shown in Fig. 3, the coaxial core parallel type flat cable of this embodiment has 25 coaxial cores 12
The coaxial cores 12 are connected in parallel only at the end portions of the cables in the longitudinal direction (front and back directions in the paper) by thermal fusion of their outermost jackets, and the pitch between signal lines is 1.27 (mm). Characteristic impedance: Z ₀ = 65±5 (Ω) at TDR, delay time: Td
=3.8±0.1 (n sec/m) st TDR.

The outer diameter of the conductor of each coaxial core 12 satisfies the above characteristic impedance and pitch between signal lines: 1.27 (mm), so it is theoretically calculated to be 0.26φ or less, but considering workability etc., it is 0.2φ ~0.25φ is preferable. In other words, if the jacket is made too thin, the insulator coated from the outside will become even thinner, and if it is made too thick, the jacket 8 will become thinner due to the limitations of the pitch between the signal lines.

As a reference example, we used a flat cable manufactured by paralleling 25 coaxial cores using a single conductor (0.23φ silver-plated copper wire) as described above, and when we performed terminal processing, we found the problem that the conductor moved. occurred. Also, as another reference example, stranded conductor:
When using seven strands of 0.08φ silver-plated copper wire with an outer diameter of 0.24φ, there was no problem with the conductor moving due to the uneven surface of the stranded wires, but there was no problem with soldering to the board. Preliminary solder was required for the application.

In this embodiment, based on the above-mentioned reference example, the stranded wire conductor in the insulated conductor of the coaxial core is improved as shown in FIG.

FIG. 1 shows an insulated conductor 11 in a coaxial core 12.
Only the bar-shaped stranded wire conductor 3 is shown. This rod-shaped stranded wire conductor 3 uses, as the wire 1, a tin-containing copper alloy (tin: approximately 0.3%) having an outer diameter of 0.08φ and having a silver plating layer with a thickness of 2 μm. Tin-containing copper alloy strand 1 with layers
The stranded wire is made by twisting seven pieces of strands of By forming the silver-plated fused portions 2, each strand is made into a rod shape while retaining the surface irregularities unique to the stranded wire and integrating each strand.

FIG. 2 shows a coaxial core 12 employing the rod-shaped stranded wire conductor 3 obtained as described above. Therefore, around the outer periphery of the rod-shaped conductor 3, ultra-highly foamed PFA (foaming ratio: 75±5%) is coated with a thickness t=0.235 as a highly foamed fluororesin insulator 4 with a foaming ratio of 70% or more.
mm (outer diameter: 0.71φ) by extrusion, and as the skin layer 5 on the outer periphery, E-
A TFE (solid) layer is applied to a thickness of t = 0.045 mm, and one silver-plated wire with an outer diameter of 0.23φ is attached vertically as the outer drain wire 6, and aluminum/polyester tape is wrapped as the shield tape wrapping layer 7. The outer periphery of the fluororesin jacket 8 is formed by extruding FEP into a rectangular outer shape.

FIG. 3 shows that 25 simultaneous cores 12 obtained as described above are arranged in parallel and integrated by heat-sealing 9 only the surfaces of the fluororesin jackets 8 at the end portions in the longitudinal direction. This is a coaxial core parallel type flat cable. In the figure, the numbers given on each coaxial core are “1, 2, 3…24, 2.
5" is the sequence number of each coaxial core.

According to the coaxial core parallel type flat cable obtained in this example, the above-mentioned characteristics were satisfied, and results with no problems were obtained in terms of terminal processing.

〔Effect of the invention〕

According to the coaxial core parallel type flat cable of the present invention constructed as described above, in the insulated conductor in each coaxial core, the conductor which is closely coated by extrusion with a highly foamed fluororesin insulator with a foaming rate of 70% or more is made of silver. The stranded wire is made of tin-containing copper alloy strands with a plating layer, and by applying a temperature high enough to melt the silver-plating layer, the contact parts of adjacent tin-containing copper alloy strands are silver-plated. Since it is made of rod-shaped stranded wire conductors connected by a fused part, the silver-plated fused part will not melt and disappear due to the high temperature heat during extrusion of fluororesin, and even after forming a coaxial core, the tin will not be removed by the silver-plated fused part. The bond between the contact parts of the copper alloy strands is maintained, and the strands can be prevented from coming loose.
In addition, because the strands of the stranded wires have roughness on their surface, the adhesion strength of the highly foamed fluororesin insulator with a foaming ratio of 70% or more, which is applied by extrusion, is improved, and the conductor is removed during terminal processing. There will be no movement.

Therefore, in the coaxial core parallel type flat cable, the coaxial core has an ultra-thin wall (thickness t = 0.3 mm).
The following) is an insulated conductor made by extruding a highly foamed fluororesin insulator with a foaming rate of 70% or more, which shares the "prevention of unraveling" of stranded wires and the "strength" of the extruded highly foamed fluororesin insulator. This in turn greatly contributed to the realization of coaxial core parallel flat cables that require high-speed signal transmission characteristics, and the effects can be said to be enormous.

[Brief explanation of the drawing]

1 to 3 show an embodiment of the coaxial core parallel type flat cable of the present invention. FIG. 3 is a cross-sectional view of a parallel coaxial core flat cable. In the symbols, 1 is a tin-containing copper alloy wire having a silver plating layer, 2 is a silver plating fused part, 3 is a rod-shaped stranded wire conductor, 4 is a highly foamed fluororesin insulator, 5 is a skin layer, and 6 is a drain wire. , 7 is a shield tape wrapping layer, 8 is a fluororesin jacket, 9 is a heat-sealed part, 1
1 is an insulated conductor, and 12 is a coaxial core.

Claims (1)

[Claims] 1. An insulated conductor 11 formed by successively applying a foamed fluororesin insulator and a skin layer to the outer periphery of the conductor by extrusion;
A drain wire 6 attached to this insulated conductor, a shielding tape wrapping layer 7 that collectively covers these insulated conductors and the drain wire, and a fluororesin coated on the outer periphery of the shielding tape wrapping layer by extrusion and having a rectangular outer shape. In a coaxial core parallel type flat cable in which a coaxial core 12 equipped with a jacket 8 is used, and a large number of the coaxial cores are arranged in parallel and fluororesin jackets are bonded together by heat fusion, the insulated conductor is rod-shaped. The rod-shaped stranded conductor consists of a stranded wire conductor 3 and a highly foamed fluororesin insulator 4 extruded and coated on its outer periphery with a foaming ratio of 70% or more. By applying a temperature high enough to melt the silver plating layer, adjacent tin-containing copper alloy strands are bonded by the silver plating fusion bonding part 2 at the contact part. , coaxial core parallel type flat cable.