JP4685744B2 - High-speed differential transmission cable - Google Patents

Description

  The present invention relates to a differential transmission cable used for internal and external connection of a high-speed server, a semiconductor tester, a mobile communication base station, etc., a connection between devices in a digital home appliance or an automobile, and more particularly, a high-speed LVDS (low voltage differential). The present invention relates to a high-speed differential transmission cable having a flat structure for high-speed data transmission represented by signal) transmission.

  The growth of the information technology industry is accelerating, and the number of powerful PCs (PCs) equipped with large storage media has increased rapidly, and with the realization of advanced telecommunications equipment, the speed has increased over long distances. A need has arisen for cables capable of data transmission. As a cable that meets this need, there is a differential transmission cable for high-speed data transmission. As a conventional differential transmission cable, for example, there is one disclosed as a conventional example of Patent Document 1. This conventional differential transmission cable will be described with reference to FIGS.

First, as a first example of a conventional differential transmission cable (single drain type), as shown in the cross-sectional view of FIG. 8, a low-density insulator (2 ′) is provided as an insulating coating layer on the outer periphery of the center conductor (1). Provided as signal lines (4H) and (4L), these two lines are arranged in parallel with each other, and one drain line (5) is vertically attached to the central valley portion of both signal lines (4H and 4L). A differential having a configuration in which an outer conductor (6) is formed by attaching an aluminum polyester tape vertically or spirally on the inner side of a metal surface while holding a three-core flat structure on the outside, and a jacket (7) is provided. There is a transmission cable (50).
Further, as a second example (dual drain type) of the conventional differential transmission cable, as shown in the cross-sectional view of FIG. 9, the electric balance of the two signal wires (4H, 4L) having the same structure as the first example is provided. As a high-spec product that supports higher bit rates, two signal lines (4H, 4L) are arranged in parallel to each other, and drain lines (5H), (5L) are vertically placed outside of them. A differential transmission cable having a configuration in which an outer conductor (6) is formed by vertically attaching or spirally winding an aluminum polyester tape on the inner side of a metal surface while maintaining a four-core flat structure, and a jacket (7) is provided. There is (60).
These differential transmission cables (50, 60) have the same center conductor size and drain wire size, and AWG (American Wire Gauge) No. 30 (7 / 0.102 mm) or No. 28 (7 / 0.127 mm) is usually used. In addition, an olefin resin foam is usually used for the low-density insulator (2 ′), and the data transmission capacity in this case is capable of transmitting a differential signal of 1.0 Gbps at a maximum of 10 m.
JP 2002-358841 A

In the differential transmission cable, the difference in capacitance between the two signal lines in the longitudinal direction and the difference in core outer diameter, that is, the relative dielectric constant is small. is necessary. Thereby, Intra-Skew (inward propagation delay time difference) between both signal lines can be reduced. In particular, when the transmission signal becomes high speed, the Intra-Skew needs to be adjusted in the ps order, and it is important to minimize the deviation of the characteristic impedance between the two lines.
In the conventional differential transmission cables (50, 60) of the first and second examples, when a low-density insulator (2 ′) of the insulating coating layer is made of a foamed insulator of olefin resin, the dielectric constant is Although low and preferable, since the shape of fine foam in the insulator is not necessarily the same bubble diameter, there is a difference in the dielectric constant between the two signal lines (4H, 4L), and the propagation delay time and characteristics between the two lines There was a problem that the impedance was shifted. If a solid insulator is used for the insulation coating layer, there are few problems with the propagation delay time between the two wires and the deviation of the characteristic impedance, but it is necessary to increase the thickness of the insulation coating layer in order to ensure the specified characteristic impedance. There are problems such as thick and hard, and deterioration of electrical characteristics such as attenuation characteristics.
In the conventional differential transmission cables of the first and second examples, since the same hue material is used for the low density insulator (2 ′), it is difficult to distinguish the two signal lines (4H, 4L). There was a problem with the terminal processability. Moreover, since PVC (polyvinyl chloride resin) is used as the material of the jacket (7), it has recently been pointed out that there are environmental problems as halogen-containing resins.
The present invention has been made in order to solve the various problems of the prior art, and the difference in capacitance between the two signal lines in the longitudinal direction and the core of two signal lines arranged in parallel with two cores. Cable configuration with a small diameter difference, small intra-skew between both signal lines, stable characteristic impedance between both signal lines, and no deviation of characteristic impedance between both signal lines, and maximum data transmission capability It is an object of the present invention to provide a high-speed differential transmission cable that can identify a signal line while taking care of the environment, is environmentally friendly, and has excellent terminal processability.

As a first aspect, the present invention provides a signal line by providing an insulating coating layer having a gap continuous in the longitudinal direction on the outer periphery of the center conductor, and arranges the signal lines in parallel with each other, and further, outside or both of the signal lines. A drain line is arranged in the central valley of the signal line, and an external conductor is formed by winding or vertically attaching a metal laminate tape, metal vapor-deposited tape, or metal tape while maintaining a 4-core or 3-core flat structure, and a jacket. The high-speed differential transmission cable is characterized in that it is coated.
In the high-speed differential transmission cable according to the first aspect, by using an insulating coating layer having a gap that is stably continuous in the longitudinal direction, the difference in capacitance between both signal lines in the longitudinal direction and the difference in core diameter can be reduced. In addition, the intra-skew between both signal lines is reduced, and the matching of the characteristic impedance is excellent.

As a second aspect, the present invention provides the insulating coating layer comprising: an inner annular portion that covers the outer periphery of the central conductor; and three or more radially extending outwards from the outer periphery of the inner annular portion. A high-speed differential transmission cable comprising a connecting portion and an outer annular portion connecting between outer ends of each connecting portion, wherein the connecting portion forms a circumferential direction of the gap portion. It is in.
In the high-speed differential transmission cable according to the second aspect, the insulating coating layer is a hollow including the inner annular portion, three or more connecting portions, and an outer annular portion that connects between outer ends of the connecting portions. An insulator is preferable, and the circumferential direction of the gap is formed at the connecting portion, and the high-speed differential transmission cable according to the first aspect is preferably obtained.

According to a third aspect of the present invention, in the insulating coating layer, the connecting portions are arranged at equiangular intervals, and three or more gap portions that are continuous in the longitudinal direction are evenly arranged in the circumferential direction around the central conductor. The high-speed differential transmission cable is characterized by
In the high-speed differential transmission cable according to the third aspect, the insulating coating layer has the connecting portions arranged at equiangular intervals, and three or more void portions continuous in the longitudinal direction are even in the circumferential direction around the central conductor. The high-speed differential transmission cable according to the second aspect is preferably obtained.

According to a fourth aspect of the present invention, there is provided the high-speed differential transmission cable according to the present invention, wherein the insulating coating layer has an area ratio of 20% to 70% in the cross section.
In the high-speed differential transmission cable according to the fourth aspect, the insulating coating layer has an area ratio of 20% or more and 70% or less (hereinafter abbreviated as a void ratio (cross-sectional area ratio)). Preferably. If the porosity (cross-sectional area ratio) is less than 20%, the insulator is thick and hard because the number of voids is small, and electrical characteristics such as attenuation characteristics are deteriorated. ) Exceeding 70% is not preferable because the strength of the insulating coating layer is reduced, and the outer conductor is easily crushed by winding the metal laminate tape or the like.

As a fifth aspect, the present invention is the high-speed differential transmission cable, wherein the insulating coating layer is made of an olefin polymer (polyolefin) resin.
In the high-speed differential transmission cable according to the fifth aspect, an olefin polymer (polyolefin) resin such as a polyethylene resin can be preferably used as the insulating coating layer.

As a sixth aspect, the present invention provides the high-speed differential transmission cable, wherein the insulating coating layer is made of a synthetic resin having a maximum continuous use temperature of 200 ° C. or higher.
In the high-speed differential transmission cable of the sixth aspect, a synthetic resin having a maximum continuous use temperature of 200 ° C. or higher can be preferably used as the insulating coating layer.

As a seventh aspect, the present invention provides the insulating coating layer comprising: PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), or PTFE (polytetrafluoroethylene). A high-speed differential transmission cable comprising a fluororesin selected from ethylene).
In the high-speed differential transmission cable according to the seventh aspect, a fluororesin selected from PFA, FEP, and PTFE can be preferably used as the insulating coating layer.

As an eighth aspect, the present invention resides in a high-speed differential transmission cable, wherein the central conductor and the drain wire are made of a single wire, a collective stranded wire or a concentric stranded wire.
In the high-speed differential transmission cable according to the eighth aspect, the central conductor and the drain wire can be preferably a single wire, a collective stranded wire, or a concentric stranded wire. The reason for limiting to single wire, collective stranded wire or concentric stranded wire is that single wire is useful in places where electrical characteristics such as attenuation characteristics and reflection characteristics are particularly important, and is also used as collective stranded wire or concentric stranded wire. This improves the bending resistance of the center conductor or drain wire.

According to a ninth aspect of the present invention, there is provided a high-speed differential transmission cable according to the present invention, wherein the central conductor and the drain wire are AWG (American Wire Gauge) Nos. 32 to 22.
In the ninth aspect of the high-speed differential transmission cable, the central conductor and the drain wire having a size of AWG Nos. 32 to 22 can be preferably used.

As a tenth aspect, the present invention is characterized in that an adhesive is preliminarily applied to the resin surface of the metal laminate tape, the metal vapor-deposited tape, or one surface of the metal tape, and is wound with the adhesive surface facing outward. There is a high-speed differential transmission cable.
In the high-speed differential transmission cable according to the tenth aspect, an adhesive is applied in advance to the resin surface of the metal laminate tape, the metal vapor-deposited tape, or one surface of the metal tape, and the wire is wound with the adhesive surface facing outside. Is preferred. As a result, the jacket and the outer conductor integrated at the time of terminal processing can be removed all at once, and a high-speed differential transmission cable excellent in terminal processability can be obtained.

As an eleventh aspect, the present invention provides a high-speed differential transmission cable, wherein the metal laminate tape, metal vapor-deposited tape, or metal tape has a tape thickness (t) of 0.005 mm ≦ t ≦ 0.050 mm. is there.
In the high-speed differential transmission cable according to the eleventh aspect, the thickness (t) of the metal laminate tape or the like is preferably 0.005 mm ≦ t ≦ 0.050 mm.
When the tape thickness (t) is less than 0.005 mm, the tape is easily cut during winding, and when the tape thickness (t) exceeds 0.050 mm, the tape becomes hard and the winding work becomes difficult. Therefore, it is not preferable.

According to a twelfth aspect of the present invention, there is provided a high-speed differential transmission cable characterized by identifying both the signal lines.
In the high-speed differential transmission cable according to the twelfth aspect, the workability at the time of processing the connector terminal can be improved by identifying both the signal lines, for example, by changing the hue of the insulating coating layer of one of the signal lines.

As a thirteenth aspect, in the present invention, instead of identifying both the signal lines, either one of the outer surfaces of the jacket is marked with one of the signal lines on the side of the jacket with ink whose hue has been changed in the longitudinal direction, or one of the outer surfaces of the jacket. In the high-speed differential transmission cable, a concave portion or a convex portion is formed in the longitudinal direction on the signal line side using a deformed die.
In the high-speed differential transmission cable according to the thirteenth aspect, one of the signal lines on the outer surface of the jacket is marked with ink having a different hue from that of the jacket in the longitudinal direction, or the one of the signal lines on the outer surface of the jacket in the longitudinal direction. In addition, by forming a concave or convex portion using a deformed die, both signal lines can be indirectly identified, and workability at the time of connector terminal processing can be improved. This indirect identification method is preferably applied when it is difficult to change the hue of the insulating coating layer of the one signal line, or when the characteristics between the two signal lines are not the same by changing the hue. be able to.

As a fourteenth aspect, the present invention is the high-speed differential transmission cable, wherein the jacket is made of lead-free PVC or non-halogen flame-retardant olefin.
In the high-speed differential transmission cable according to the fourteenth aspect, an environment-friendly product can be obtained by using lead-free PVC or non-halogen flame-retardant olefin as the jacket material.

As a fifteenth aspect, the present invention resides in a high-speed differential transmission cable characterized in that the high-speed differential transmission cable can transmit a high-speed digital signal of 1 Gbps or more.
The high-speed differential transmission cable of the fifteenth aspect is preferable because it can transmit a high-speed digital signal of 1 Gbps or more.

According to a sixteenth aspect of the present invention, in the high-speed differential transmission cable, a drain line is disposed outside the signal line or at the center of both signal lines, and the outer periphery of the high-speed differential transmission cable is maintained while maintaining a four-core or three-core flat structure. A high-speed differential transmission characterized in that a stable 4-core or 3-core flat structure is formed by a dedicated tape winding device capable of stably winding the metal laminate tape, metal vapor-deposited tape or metal tape. In the cable.
In the high-speed differential transmission cable according to the sixteenth aspect, the high-speed differential transmission cable has a stable 4-core or 3-core flat structure formed by a dedicated tape winding device capable of stably winding a metal laminate tape or the like. Is done.

According to a seventeenth aspect of the present invention, in the high-speed differential transmission cable, the integrated jacket and a predetermined length of the outer conductor are collectively removed by a hot blade or a mechanical blade to expose both signal lines and drain lines. Further, remove the specified length of the insulation coating layer with a hot blade or a mechanical blade to expose the center conductor, and melt the end portion of the insulation coating layer with a hot blade, or use an adhesive, coating agent or hot The high-speed differential transmission cable is characterized in that a terminal process is performed in which a gap is covered by covering with a melt resin.
In the high-speed differential transmission cable according to the seventeenth aspect, the terminal processing makes it easy to connect to the cable connector, and flux and moisture enter the gap portion of the insulating coating layer to deteriorate the electrical characteristics. Can be prevented.

According to the high-speed differential transmission cable of the present invention, by using an insulating coating layer having a gap portion that is stable and continuous in the longitudinal direction, two signal lines arranged in parallel with two cores are used as the insulating coating layer. The difference in capacitance between both signal lines in the longitudinal direction and the difference in core diameter are kept to a minimum. Intra-skew between both signal lines is reduced, and the matching of characteristic impedance is excellent.
In addition, the two signal lines are identified, or one of the signal lines on the outer surface of the jacket is marked with ink having a different hue from the jacket in the longitudinal direction, or one of the signal lines on the outer surface of the jacket is recessed or protruded. By forming the portion, both signal lines can be identified directly or indirectly, and workability at the time of processing the connector terminal can be improved. Further, by using non-lead PVC or non-halogen flame retardant olefin as the material of the jacket, an environment-friendly product can be obtained. Moreover, a stable 4-core or 3-core flat structure can be formed by using a dedicated tape winding device that can stably wind the metal laminate tape or the like. The high-speed differential transmission cable of the present invention can transmit a high-speed digital signal of 1 Gbps or more. Further, the terminal processing makes it easy to connect to the cable connector, and it is possible to prevent the flux and moisture from entering the gap portion of the insulating coating layer and deteriorating the electrical characteristics.
Therefore, the present invention has an extremely large effect contributing to the industry.

Hereinafter, the contents of the high-speed differential transmission cable of the present invention will be described in more detail with reference to embodiments shown in the drawings. Note that the present invention is not limited thereby.
FIG. 1 is a sectional view showing a first embodiment (single drain type) of the high-speed differential transmission cable of the present invention. FIG. 2 is a sectional view showing a second embodiment (dual drain type) of the high-speed differential transmission cable of the present invention. FIG. 3 is a sectional view showing a third embodiment (single drain type) of the high-speed differential transmission cable of the present invention. FIG. 4 is a cross-sectional view showing a fourth embodiment (single drain type) of the high-speed differential transmission cable of the present invention. FIG. 5 is a schematic view showing an example of a hot blade used for terminal processing according to the present invention, in which FIG. 5 (a) is a front view of a jacket layer hot blade, and FIG. 5 (b) is a front view of an insulating coating layer hot blade. FIG. 1C is a left side view of FIG. FIG. 6 is a schematic diagram showing an example of a high-speed differential transmission cable terminal processed product. FIG. 7 is a chart of an outer diameter / capacitance stability comparison test in the longitudinal direction of the insulator. FIG. 7A is an insulator of the high-speed differential transmission cable of Example 1, and FIG. These are insulators of the differential transmission cable of Comparative Example 1.
In these drawings, 1 is a central conductor, 2, 2x and 2y are insulating coating layers (hollow insulators), 2a is an inner annular portion, 2b is a connecting portion, 2c is an outer annular portion, 2d is a gap portion (cross-sectional fan shape) ), 2e is a gap (elliptical cross section), 2f is a gap (cross section), 2h is an insulating coating layer end, 4, 4a, 4b, 4c, 4d, 4e, 4f, 4g, 4h are signals 5, 5 a, 5 b are drain wires, 6 is an external conductor (metal laminate tape, metal evaporated tape or metal tape), 7 is a jacket, 10, 20, 30, 40 are high-speed differential transmission cables, and 20 a is a high-speed differential cable. Dynamic transmission cable terminal processed product (high-speed differential transmission cable), n1 and n2 are hot blades, o is a blade portion, p is a heat melting portion, q is a round groove portion, t is a protrusion, and y is a melting end portion.

A first embodiment (Example 1) of the high-speed differential transmission cable of the present invention will be described with reference to FIG.
AWG No. 28 (7 / 0.127 mm) with a silver-plated annealed copper stranded wire having an outer diameter of 0.38 mm as a central conductor (1), an inner annular portion (2a) covering the outer periphery, and an inner annular portion (2a) Six connecting portions (2b) arranged radially at equal angular intervals (60 degrees) radially outward from the outer periphery and continuous in the longitudinal direction, and an outer ring connecting the outer ends of these connecting portions (2b) Insulation coating layer (hollow insulator) (2) in which six voids (2d) having a fan-shaped cross section continuous in the longitudinal direction by the portion (2c) are arranged evenly in the circumferential direction around the central conductor (1) Was prepared by extruding PFA of fluororesin to a thickness of 0.280 mm to produce a signal line (4) having a porosity of 60% (cross-sectional area ratio).
Next, the signal wires 2 cores (4a, 4b) are arranged in parallel, and the drain wire (5) made of the same AWG 28 silver-plated annealed copper stranded wire as the central conductor (1) is arranged in the central valley portion of the 2 signal wires. Arranged vertically and holding a 3-core flat structure, an aluminum polyester tape with a resin surface adhesive layer of 0.015 mm in thickness is spirally wound inside the metal surface, 2 signal lines (4a, 4b) and drain lines The outer conductor (6) was formed so as to surround (5). Further, a non-halogen flame-retardant olefin resin jacket (7) is coated on the outside with a thickness of 0.25 mm so as to adhere to the outer conductor (6), thereby producing a single drain type high-speed differential transmission cable (10). did. In addition, only one signal line (4b) out of the two signal lines is colored with PFA in blue with a colorant so that the signal line two cores (4a, 4b) can be identified to improve workability when processing the connector terminal. I planned. In addition, a special taping machine equipped with a multi-head feeder, a special wire-shaping die chip, and a forming pulley was used for spiral winding of the aluminum polyester tape.
Here, AWG No. 28 silver-plated annealed copper stranded wire (concentric stranded wire) was used for the central conductor (1) and drain wire (5), but it may be a single wire or a collective stranded wire of copper or copper alloy wire. No. (AWG Nos. 32 to 22), configuration, material, and plated product may be used. Further, as the insulating coating layer (2), FEP or PTFE, or an olefin polymer resin can be used in addition to the fluororesin PFA. Moreover, although the aluminum polyester tape with an adhesive layer was used for the external conductor (6), other metal laminate tapes (including those without an adhesive layer), metal vapor-deposited tapes or metal tapes may be used. The tape thickness can be varied from 0.005 to 0.05 mm. Note that the metal laminate tape or the like may be longitudinally attached in addition to the spiral winding. The material of the jacket (7) may be flame retardant non-lead PVC or other resin as usual.

A second embodiment (Example 2) of the high-speed differential transmission cable of the present invention will be described with reference to FIG.
An AWG No. 26 (7 / 0.160 mm) and a silver-plated annealed copper stranded wire having an outer diameter of 0.48 mm as a central conductor (1), an inner annular portion (2a) covering the outer periphery, and an inner annular portion (2a) Six connecting portions (2b) arranged radially at equal angular intervals (60 degrees) radially outward from the outer periphery and continuous in the longitudinal direction, and an outer ring connecting the outer ends of these connecting portions (2b) The hollow insulator (2) in which six gaps (2d) having a fan-shaped cross section continuous in the longitudinal direction by the portion (2c) are arranged uniformly in the circumferential direction around the central conductor, and PFA of 0.31 mm A signal line (4) having a porosity of 53% (cross-sectional area ratio) was manufactured by extruding the thickness.
Next, two signal wires (4) (4c and 4d) are prepared, these two wires are arranged in parallel with two cores, and further, the drain wires (5a, 5a, 5b) are arranged vertically, and an aluminum polyester tape with a resin surface adhesive layer having a thickness of 0.015 mm is spirally wound inside the metal surface while maintaining a four-core flat structure, and two signal wires (4c, 4d) ) And the drain wire (5a, 5b), the outer conductor (6) was formed. Note that the two signal lines (4c, 4d) are not color-coded.
Further, a non-halogen flame-retardant olefin resin jacket (7) was coated on the outside so as to adhere to the outer conductor (6) with a thickness of 0.25 mm, and a dual drain type high-speed differential transmission cable (20) was manufactured. .
When covering the jacket (7), a protrusion (t) was formed with a deformed die along the longitudinal direction on one signal line (4c) side of the outer surface of the jacket. As a result, the position where the two signal wires (4c, 4d) are present inside the cable can be identified externally, and the workability at the time of processing the connector terminal is improved.

  A third embodiment (Example 3) of the high-speed differential transmission cable of the present invention will be described with reference to FIG. In the high-speed differential transmission cable (30) of Example 3, the cross-sectional shape of the six gaps (2e) in the hollow insulator (2x) is elliptical, and the gap (2d) of Example 1 Otherwise, the structure is the same as that of the high-speed differential transmission cable (10) of the first embodiment. The gap (2e) may be oval or circular in cross section. The hollow insulator (2x) having an elliptical void portion has an advantage that the cross-sectional shape of the void portion is elliptical so that the strength is improved and it is difficult to be crushed when a force is applied from the outside.

  A fourth embodiment (Example 4) of the high-speed differential transmission cable of the present invention will be described with reference to FIG. In the high-speed differential transmission cable (40) of Example 4, the cross-sectional shape of the six air gaps (2f) in the hollow insulator (2y) is a cross-section (the air gap having the cross-sectional fan shape of Example 1). This is the same structure as the high-speed differential transmission cable of the first embodiment except that it is different from the gap (2d) of the first embodiment. The hollow insulator (2y) having the void portion having the cross-sectional shape has an advantage that the strength is improved because the central portion of the connecting portion (2b) is thick, and that it is difficult to be crushed when force is applied from the outside. .

5th Embodiment (Example 5) (terminal processed product) of the high-speed differential transmission cable of this invention is demonstrated using FIG. 5, FIG.
A predetermined length of the high-speed differential transmission cable (20) obtained in Example 2 is prepared, and a hot blade (n1) (n1) shown in FIG. After scratching with the blade part (o) at a temperature of about 250 ° C., the jacket of the part to be removed is pulled, and the predetermined lengths of the integrated jacket (7) and the external conductor (6) are removed at a time. (4c, 4d) and drain lines (5a, 5b) were exposed.
Next, it is provided at a predetermined position of both exposed signal lines (4c, 4d) in the hot melt part (p) of the hot blade (n2) (temperature of about 350 ° C.) shown in FIGS. 5 (b) and 5 (c). The circular groove (q) is melted while crushing the end portion (2h) of the insulating coating layer of the high-speed differential transmission cable (20a) shown in FIG. 6 to cover and cover the gap (2d) (not shown). The melted end (y) is provided, and the blade (o) is scratched at a predetermined position of the insulating coating layer (2), and then the portion of the insulating coating layer to be removed is pulled to increase the predetermined length of the insulating coating layer. Terminal processing of removing and exposing the central conductor (1) was performed to manufacture a high-speed differential transmission cable terminal processed product (20a). The hot blades (n1) and (n2) are connected to a heater and a temperature controller (not shown) and can be set to an arbitrary temperature. It is also possible to remove the predetermined length of the insulating coating layer (2) using the hot blade (n1). In this case, as a method of covering the end surface of the insulating coating layer, an adhesive, a coating agent, or It is desirable to apply hot melt resin.
In the terminal processed product (20a), by providing the melt end portion (y), it is possible to prevent the flux and moisture from entering the gap portion (2d) of the insulating coating layer (2) to deteriorate the electrical characteristics. I was able to. Further, when the data transmission performance of the processed terminal product (20a) was measured, a high-speed digital signal of 1 Gbps or more could be transmitted.

(Comparative Example 1)
The differential transmission cable (single drain type) of Comparative Example 1 will be described. The differential transmission cable of Comparative Example 1 has the same structure as the first example (single drain type) of the conventional differential transmission cable shown in FIG. 8, and has a low-density insulator (2 ′) with an insulating coating layer. The foamed polyethylene resin is coated with a thickness of 0.275 mm. The constituent materials other than the insulating coating layer, the central conductor, and the drain wire (tin-plated annealed copper stranded wire) are the same as those in Example 1.

―Characteristic test of high-speed differential transmission cable―
The high-speed differential transmission cable of Example 1 and the differential transmission cable of Comparative Example 1 were tested for the stability of the outer diameter / capacitance in the longitudinal direction of the insulator and the intra-skew characteristics. The test results will be described. Although the high-speed differential transmission cable of Example 2 was also tested, the characteristics were the same as those of the high-speed differential transmission cable of Example 1, and the description thereof will be omitted.
(1) Stability comparison test of the outer diameter and capacitance in the insulator longitudinal direction The outer diameter in the insulator longitudinal direction is measured using a laser outer diameter measuring instrument, and the capacitance is measured using a capacitance monitor. Measured and recorded simultaneously on a pen recorder chart. The test results are shown in the chart of FIG. 1A is an insulator of the high-speed differential transmission cable of the first embodiment, and FIG. 1B is an insulator of the differential transmission cable of the first comparative example. In this chart, the upper side of the chart is the minus side and the lower side is the plus side.
As is apparent from the chart of FIG. 7, the high-speed differential transmission cable of the present invention has a very stable electrostatic capacitance in the longitudinal direction of the insulator and a small fluctuation in outer diameter level.
Therefore, the variation in the porosity of the insulator will be considered. Since the outer diameter variation of the insulator is almost the same in Example 1 and Comparative Example 1, it was assumed that the outer diameter of the insulator was constant, and the capacitance change was converted into the porosity change for comparison. As a result, the differential transmission cable of Example 1 has a maximum porosity variation of 2.4%, while the high-speed differential transmission cable of Comparative Example 1 has a maximum porosity variation of 5.7%. It can be seen that this cable has extremely small characteristics in the porosity in the longitudinal direction of the insulator and has excellent characteristics. In addition, the conversion formula which calculated | required the porosity variation is abbreviate | omitted.

(2) Intra-Skew characteristic test For the differential transmission cables of Example 1 and Comparative Example 1, the sample lot is set to 3, and the Intra-Skew characteristic is measured by a TDR measuring instrument (Nippon Tektronix: TDS8000, sampling head 80E04). The cable was connected via a special jig processed semi-rigid cable. The test results are shown in Table 1 below.
As is clear from the test results in Table 1, the high-speed differential transmission cable of the present invention has extremely small Intra-Skew maximum value, minimum value, and average value compared to the differential transmission cable of the comparative example. It can be seen that the intra-skew between the lines is greatly reduced.

  The high-speed differential transmission cable of the present invention can be used for internal and external connection of a high-speed server, semiconductor tester, mobile communication base station, etc., connection between devices in digital home appliances and automobiles, etc., especially as represented by high-speed LVDS transmission. It can be suitably used for high-speed data transmission.

It is sectional drawing which shows the 1st example (single drain type) of the high-speed differential transmission cable of this invention. It is sectional drawing which shows the 2nd example (dual drain type) of the high-speed differential transmission cable of this invention. It is sectional drawing which shows the 3rd example (single drain type) of the high-speed differential transmission cable of this invention. It is sectional drawing which shows the 4th example (single drain type) of the high-speed differential transmission cable of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic which shows an example of the hot blade used for the terminal processing of this invention, The figure (a) is a front view of the hot blade for jacket layers, The figure (b) is a front view of the hot blade for insulation coating layers, FIG. 4C is a left side view of FIG. It is the schematic which shows an example of the high-speed differential transmission cable terminal processed goods of this invention. It is a chart of the outer diameter / capacitance stability comparison test in the longitudinal direction of the insulator, where FIG. (A) is the insulator of the high-speed differential transmission cable of Example 1, and (b) is Comparative Example 1. It is an insulator of a differential transmission cable. It is sectional drawing which shows the 1st example (single drain type) of the conventional differential transmission cable. It is sectional drawing which shows the 2nd example (dual drain type) of the conventional differential transmission cable.

Explanation of symbols

1 Center conductor 2, 2x, 2y Insulation coating layer (hollow insulator)
2a Inner ring part 2b Connection part 2c Outer ring part 2d Air gap part (cross-section fan shape)
2e Cavity (elliptical cross section)
2f Cavity (Cross section)
2h Insulation coating layer end 4, 4a, 4b, 4c, 4d, 4e, 4f, 4g, 4h Signal line 5, 5a, 5b Drain line 6 External conductor (metal laminate tape, metal vapor-deposited tape or metal tape)
7 Jacket 10, 20, 30, 40 High-speed differential transmission cable 20a Finished product of high-speed differential transmission cable (high-speed differential transmission cable)
n Hot blade o Blade portion p Thermal melting portion q Round groove portion t Projection y Melting end portion

Claims (17)

  An insulating coating layer having a gap continuous in the longitudinal direction is provided on the outer periphery of the central conductor to form a signal line, which is arranged in parallel with two cores, and further drain lines on the outside of both signal lines or on the central valley between both signal lines. The outer conductor is formed by winding or vertically attaching a metal laminate tape, metal vapor-deposited tape or metal tape while maintaining a four-core or three-core flat structure, and covering this with a jacket High-speed differential transmission cable.   The insulating coating layer includes an inner annular portion covering the outer periphery of the center conductor, three or more connecting portions extending radially outward from the outer periphery of the inner annular portion, and outer portions of the connecting portions. 2. The high-speed differential transmission cable according to claim 1, wherein the high-speed differential transmission cable is a hollow insulator having an outer annular portion that connects between ends, and the connecting portion forms a circumferential direction of the gap portion.   The insulating coating layer is characterized in that the connecting portions are arranged at equiangular intervals, and three or more void portions that are continuous in the longitudinal direction are evenly arranged in the circumferential direction around the central conductor. Item 3. A high-speed differential transmission cable according to item 2.   4. The high-speed differential transmission cable according to claim 1, wherein the gap covers 20% or more and 70% or less in an area ratio in the cross section of the insulating coating layer.   The high-speed differential transmission cable according to claim 1, wherein the insulating coating layer is made of an olefin polymer (polyolefin) resin.   5. The high-speed differential transmission cable according to claim 1, wherein the insulating coating layer is made of a synthetic resin having a maximum continuous use temperature of 200 ° C. or more.   The insulating coating layer is made of a fluororesin selected from PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), or PTFE (polytetrafluoroethylene). The high-speed differential transmission cable according to claim 6.   The high-speed differential transmission cable according to claim 1, 2, 3, 4, 5, 6 or 7, wherein the central conductor and the drain wire are made of a single wire, a collective strand wire or a concentric strand wire.   9. The high-speed differential transmission cable according to claim 8, wherein the central conductor and the drain line are AWG (American Wire Gauge) Nos. 32 to 22.   10. The adhesive according to claim 1, wherein an adhesive is applied in advance to one side of the metal laminate tape, the metal vapor-deposited tape, or the metal tape, and is wound with the adhesive surface facing outward. High-speed differential transmission cable.   11. The high-speed differential transmission cable according to claim 1, wherein a tape thickness (t) of the metal laminate tape, the metal vapor-deposited tape, or the metal tape is 0.005 mm ≦ t ≦ 0.050 mm.   12. The high-speed differential transmission cable according to claim 1, wherein the both signal lines are identified.   Instead of identifying both signal lines, mark one of the signal lines on the outer surface of the jacket with ink that has a different hue from the jacket in the longitudinal direction, or deform it in the longitudinal direction on one signal line side of the outer surface of the jacket. The high-speed differential transmission cable according to claim 1, wherein a concave portion or a convex portion is formed using a die.   The high-speed differential transmission cable according to claim 1, wherein the jacket is made of lead-free PVC or non-halogen flame-retardant olefin.   The high-speed differential transmission cable according to any one of claims 1 to 14, wherein the high-speed differential transmission cable is capable of transmitting a high-speed digital signal of 1 Gbps or more.   The high-speed differential transmission cable according to any one of claims 1 to 15, wherein a drain line is arranged outside the signal line or at the center of both signal lines, and the four-core or three-core flat structure is maintained. High-speed differential characterized in that a stable 4-core or 3-core flat structure is formed on the outer periphery by a dedicated tape winding device capable of stably winding the metal laminate tape, metal vapor-deposited tape or metal tape. Transmission cable. The high-speed differential transmission cable according to any one of claims 1 to 16, wherein a predetermined length of the integrated jacket and outer conductor is collectively removed by a hot blade or a mechanical blade to expose both signal lines and drain lines, and The exposed conductors are further removed with a hot blade or a mechanical blade to remove a predetermined length of the insulating coating layer to expose the center conductor, and the end of the insulating coating layer is melted with a hot blade, or an adhesive, coating agent or A high-speed differential transmission cable, characterized in that it has been subjected to terminal processing that covers the gap by coating with hot-melt resin.