JP3669562B2 - Differential signal transmission cable with excellent terminal processability - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a differential signal transmission cable used for internal wiring of large-sized devices such as various communication devices and computers, and in particular, as represented by high-speed LVDS (Low Voltage Differential Signaling) transmission. The present invention relates to a differential signal transmission cable for high-speed data transmission. The differential transmission cable is a digital transmission cable that has a pair of central conductors and operates at a potential of + V and −V, is resistant to external noise, and can be transmitted over a long distance.
[0002]
[Prior art]
In fields such as high-end processor systems, multimedia, and networking, which have been growing rapidly in recent years, higher data transmission rates have been demanded than before. For example, in spite of a transmission distance of about 10 m, a large amount of data must be transmitted in real time and synchronously, and a differential signal transmission cable (hereinafter abbreviated as a differential transmission cable) suitable for this is required.
A conventional differential transmission cable will be described with reference to the cross-sectional structure diagram of FIG. 2A is a conventional type 1 differential signal transmission cable, FIG. 2B is a conventional type 2 differential signal transmission cable, and FIG. 3C is a conventional type 3 differential signal transmission cable. It is.
First, as a first conventional example, as shown in FIG. 5A, a low-density insulator (for example, made of polyethylene foam) is formed on the outer periphery of a central conductor (1) composed of, for example, seven conductor wires. 2), and a skin layer (3) is provided on the outer periphery to form a signal line (4). Two of the signal lines (4) (core) and a strand of, for example, seven conductor strands next to the signal line (4) 3 drain wires (6) consisting of a total of 3 parallel wires, and an outer side with aluminum polyester tape (hereinafter abbreviated as “alpet”) spirally or vertically attached inside the metal surface. And a differential transmission cable (30) (hereinafter referred to as a conventional type 1) having a jacket layer (8) coated on the outer periphery.
As a second conventional example, as shown in FIG. 5B, two signal wires (4) (core) similar to those in the first example are arranged in parallel, and a central valley portion of the two wires is arranged. A drain wire (6) is vertically attached to the outside, and an outer conductor (5) is provided on the outside by spirally winding or vertically attaching an alpet inside the metal surface, and the jacket layer (8) is covered on the outer periphery. There is a dynamic transmission cable (40) (hereinafter referred to as conventional type 2).
Furthermore, as a third conventional example, as shown in FIG. 5 (c), two signal wires (4) (core) and one drain wire (6) are twisted as in the first example. A differential transmission cable (50) with an outer conductor (5) provided on the outside and spirally wound or vertically attached on the inner side of the metal surface and covered with a jacket layer (8) on the outer periphery (hereinafter referred to as conventional type 3) Called).
The conventional differential transmission cables 1 to 3 can transmit signals of TIA / EIA-422-B and 485 standards for a long distance of 1 km, for example, but the data transmission rate in this case is about 10 Mbps. (However, when the cable length is 12m). The most excellent current product is the conventional 3-type configuration, which can transmit a differential signal of 1.0 Gbps for 10 m.
[0003]
[Problems to be solved by the invention]
However, the conventional type 1 differential transmission cable (30), when the drain wire (6) and the Alpet metal surface of the outer conductor (5) are brought into firm contact, the low density insulator ( 2) The drain wire (6) bites into the low-density insulator, and the differential impedance of the differential transmission cable signal core (hereinafter also referred to as differential pair) (4, 4) is balanced. or collapse, inward (in the differential pair) propagation delay time difference (hereinafter, abbreviated as inward skew) there has been a problem that caused to occur. If the contact between the drain wire (6) and the Alpet metal surface is weakened to eliminate the bite into the low density insulator (2), the potential between each signal line and ground (between the drain lines) changes. End up. In addition, when the skin layer (3) on the insulator surface is made thick and firm in order to prevent the low-density insulator (2) from being crushed, there is a problem that the dielectric constant and the dielectric loss tangent deteriorate and the signal transmission quality decreases. .
In addition, the conventional type 2 differential transmission cable (40) can be used when the alpet is wound with high tensile strength so that the drain wire (6) and the Alpet metal surface of the outer conductor (5) are firmly contacted. (6) is pushed in the winding direction and crushes the low-density insulator (2) in the contact part (s), causing the balance in the differential pair (4, 4) to be lost or causing skew (propagation delay time difference). There was a problem of causing it. In addition, as in the case of the conventional type 1, if the skin layer (3) on the insulator surface is made thick and firm to prevent the low-density insulator (2) from being crushed, the dielectric constant and dielectric loss tangent deteriorate and the signal transmission quality is reduced. There was a problem of lowering.
In addition, it has been difficult to control the supply tension of the conventional three-type differential transmission cable (50) when twisting three pieces with a twister. The variation in tension caused the variation in physical length between the two signal wires (4, 4), which caused an increase in skew. Further, since the finished cross-sectional shape is close to a circle, there is a drawback that the finished outer diameter (thickness direction) is larger than that of the parallel type.
The present invention has been made in order to solve the various problems of the prior art described above, and maintains the balance of characteristic impedance and ground balance in the differential pair, reduces the inward and inter-pair skew, and crosstalk. An object of the present invention is to provide a differential transmission cable with little (crosstalk), particularly capable of high bit rate transmission of 500 Mbps or more, and excellent workability and terminal workability.
[0004]
[Means for Solving the Problems]
As a first aspect, the present invention arranges two signal lines (4) in which a low-density insulating layer (2) and a skin layer (3) are sequentially provided on the outer periphery of the central conductor (1) in parallel. An outer conductor (5) is provided on the outer periphery of the two signal wires (4, 4) so as to surround the conductive tape having an adhesive layer on a part of the metal surface of the conductive tape. A drain wire (6) is vertically attached to the outside, and a synthetic resin tape provided with an adhesive layer on one side of the resin tape is wound around the outer periphery of the drain wire (6) and the outer conductor (5) to hold and synthesize A differential signal transmission cable (9) provided with a resin tape layer (7) and further coated with a jacket layer (8) on the outer periphery thereof, wherein the conductive tape is a metal laminate tape, a metal vapor-deposited tape or a metal tape The outer conductor (5) is formed by being spirally wound or vertically attached with the adhesive layer of the metal surface on the outside, and the drain wire (6) is the outer conductor (5) Outside , the adhesive layer is placed on the outside so that it is vertically attached to one or both of the central outer side and / or the lateral outer side of the two signal wires (4, 4) and is made to adhere to the outer conductor (5) with the synthetic resin tape. The differential signal transmission cable (9) is excellent in terminal processability and is characterized by being pressed and wound.
In the differential signal transmission cable (9) according to the first aspect, the drain wire (6) is vertically attached on the metal tape layer of the conductive tape wound as the outer conductor (5), whereby the conventional type 1 And the drain line (6) does not bite into the low-density insulating layer (2) of the signal line (4) and is not crushed unevenly as in the case of type 2 and type 2 cables. It is possible to prevent the balance of the balanced system characteristic impedance from being lost. In addition, the drain wire (6) and the outer conductor (5) are provided with a holding tape layer (7) by winding a synthetic resin tape around the outer periphery of the drain wire (6) and the outer conductor (5). ) Is securely adhered to the metal surface, so that the ground is stably secured, and the potentials between the differential pair (4, 4) and the drain line (6) are equal, and good signal transmission characteristics can be obtained. In addition, since the two signal wires (4, 4) are parallel without twisting like the conventional type 3 cable, the physical lengths of the signal wires (4, 4) are always equal and no skew occurs. . Further, even if the conventional type 3 twist type and the finished outer diameter (short diameter) are compared, the parallel type is small and advantageous. Also, compared to the conventional type 1 cable, the drain wire (6) is easily positioned and stable, so that the cable can be manufactured relatively easily.
In the differential signal transmission cable (9) according to the first aspect, an adhesive layer is provided on a part of the metal surface of the conductive tape and is spirally wound or vertically attached with the adhesive layer facing outside. The conductor (5) and the synthetic resin tape layer (7) can be adhered. Further, since the adhesive layer is provided on one surface of the synthetic resin tape and is wound with the adhesive layer facing outward, the synthetic resin tape layer (7) and the jacket layer (8) can be adhered. Accordingly, at the time of terminal processing, only the drain wire (6) is left, and the external conductor (5) can be peeled off at once.
[0005]
As a second aspect, the present invention resides in a differential signal transmission cable (9) excellent in terminal processability , wherein the thickness (t) of the conductive tape is 0.010 mm ≦ t ≦ 0.050 mm. The reason why the thickness (t) of the conductive tape is limited to the above range is that the mechanical strength of the tape, the low tension winding process, and the flexibility of the cable are taken into consideration. It is desirable to select a thin one in the sense of improving transmission characteristics and terminal processability.
In the differential signal transmission cable (9) of the second aspect, since the thickness (t) of the conductive tape is within the above range and is relatively thin, the flexibility of the cable is not impaired and the tape is wound. Workability is improved. That is, since low tension, for example, 200 to 300 g can be wound, the low-density insulating layer (2) of the signal line (4) is not easily crushed.
[0006]
As a third aspect, the present invention resides in a differential signal transmission cable (9) excellent in terminal processability in which the thickness (u) of the synthetic resin tape is 0.004 mm ≦ u ≦ 0.030 mm. The reason why the thickness (u) of the synthetic resin tape is limited to the above range is in consideration of the mechanical strength of the tape, the low tension winding process, and the flexibility of the cable. It is desirable to select a thin one in order to improve the performance, transmission characteristics and terminal processability.
In the differential signal transmission cable (9) according to the third aspect, since the thickness (u) of the synthetic resin tape is within the above range and is relatively thin, the flexibility of the cable is not impaired, and the tape winding is not performed. The workability of turning is improved. That is, since low tension, for example, 150 to 250 g winding processing is possible, the low-density insulating layer (2) of the signal line (4) is not easily crushed.
[0007]
The fourth of the present invention as aspect, terminal workability characterized by pre SL aspect 1, 2 or 3 that are aligned and fused to any one aspect of the terminal workability excellent differential signal transmission cable (9) Excellent differential signal transmission cable (10) .
The differential signal transmission cable (10) according to the fourth aspect can be easily obtained by aligning and fusing the differential signal transmission cable (9) .
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the contents 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 structural view of a differential signal transmission cable according to an embodiment (Example) 1 of the present invention. FIG. 2 is a cross-sectional structural view showing another embodiment of the differential signal transmission cable of the present invention. FIG. 2 (a) shows the differential signal transmission cable of Example 2, and FIGS. 2 (b) and 2 (c). Are the dual drain type differential signal transmission cables of Examples 3 and 4, respectively. FIG. 3 is a sectional structural view of a differential signal transmission cable according to a fifth embodiment of the present invention. FIG. 4 is a chart showing eye pattern measurement results of the differential signal transmission cable.
In these drawings, 1 is a central conductor, 2 is a low density insulating layer, 3 is a skin layer, 4 is a signal line, 5 is an external conductor (conductive tape), 6 is a drain line, 7 is a press-wrapping synthetic resin tape layer, 8 is a jacket layer, 9, 9a, 9b and 9c are differential signal transmission cables excellent in terminal processability, and 10 is a differential signal transmission cable excellent in terminal processability.
[0009]
-Embodiment (Example) 1-
A differential signal transmission cable excellent in terminal processability according to the first embodiment will be described with reference to FIG.
A silver-plated annealed copper stranded wire having an outer diameter of 0.38 mm (7 / 0.127 mm) is used as the center conductor (1) , and a porous tetrafluoroethylene copolymer resin (PTFE ) is used as a low-density insulating layer (2) on the outer periphery. ) tape wound in a thickness of 0.23 mm, then the skin layer on the outer periphery (3) as a tetrafluoroethylene - provided perfluoroalkylvinylether resin (PFA) resin to a thickness of 0.060mm signal lines ( 4) . Then the outer periphery of the signal line (4) of the two parallel to contact the aligned signal line 2 cores (4, 4), the signal line 2 core (4, 4) so as to encloses the metal surface An outer conductor (5) was formed by spirally winding an alpet (with an aluminum surface zebra adhesive layer) having a thickness of 0.015 mm with the outer side facing outside . The winding tension at this time was about 250 g. Next, a silver plated annealed copper stranded wire having an outer diameter of 0.38 mm which is the same as that used for the central conductor (1) is used as the drain wire (6) , and two signal wires (4 ) are provided outside the outer conductor (5). , from the longitudinal served to the central outer portion of 4), the drain line (6) the outer conductor (5 for the purpose of close contact with the metal surface), thickness 0.010mm adhesive layer with the polyethylene terephthalate resin (PET) The tape was wound around the outer periphery of the drain wire (6) and the outer conductor (5) with the adhesive surface outside, and a press-wrapping synthetic resin tape layer (7) was provided. The winding tension at this time was about 200 g. Further, a polyvinyl chloride resin (PVC ) as a thermoplastic resin is extruded to a thickness (average thickness) of about 0.30 mm as a jacket layer (8) on the outer periphery thereof , and the cross-sectional shape is substantially square (short axis about 1.8 mm × A differential signal transmission cable (9) having a major axis of about 2.6 mm was manufactured.
As the outer conductor (5) of Example 1, an alpet with a zebra adhesive layer is used, but other metal laminate tape, metal vapor-deposited tape, metal tape or other conductive tape is used with the metal surface facing outward. Can be spirally wound or vertically attached. The thickness of the conductive tape can also be varied from 0.010 mm to 0.050 mm. Moreover, as the presser tape layer (7) , a PET tape with an adhesive layer is used, but synthetic resin tapes of other materials may be used. The thickness of the resin tape can also be varied from 0.004 mm to 0.030 mm. A spot-like adhesive layer or the like may be used instead of the zebra adhesive layer. Although the thickness of the skin layer (3) is not particularly limited, it may be about 0.060 mm in Example 1. On the other hand, in the conventional types 1 and 2, crushing has been confirmed even with a PFA skin layer thickness of 0.10 mm.
[0010]
-Embodiment (Example) 2-
A differential transmission cable excellent in terminal processability of Example 2 will be described with reference to FIG.
The differential transmission cable (9a) has the same structure as that of the first embodiment. However, the counts of the central conductor (1) and the drain line (6) are changed to AWG No. 30, and the skin layer (3) is changed to a PET skin layer with an adhesive layer .
[0011]
-Embodiment (Example) 3-
A differential transmission cable excellent in terminal processability of Example 3 will be described with reference to FIG.
This differential transmission cable (9b) is a dual drain type differential signal transmission cable, the drain wire (6) is outside the outer conductor (5) , and the signal wire 2 core (4 , 4) is laterally outside. Each one is attached vertically. The basic constituent material of the differential transmission cable (9b ) is the same as that of the differential transmission cable (9) of the first embodiment .
[0012]
-Embodiment (Example) 4-
A differential transmission cable excellent in terminal processability of Example 4 will be described with reference to FIG.
The differential transmission cable (9c) is a dual drain type differential signal transmission cable as in the third embodiment, but the drain line (6) is outside the outer conductor (5) and the signal line 2 One core is vertically attached to both of the central outer portions of the cores (4 , 4) . The basic constituent material of the differential transmission cable (9b ) is the same as that of the differential transmission cable (9) of the first embodiment .
[0013]
-Embodiment (Example) 5-
A differential transmission cable excellent in terminal processability of Example 5 will be described with reference to FIG.
The differential signal transmission cable (9) obtained in Example 1 was used as one unit, and 5 units were aligned and heat-sealed to produce a differential signal transmission cable (10) . The number of units is suitably 2 to 40 units, for example. As a method for fusing, an adhesive, a paper adhesive tape, or the like can be used in addition to the heat fusing.
[0014]
Comparative example
-Comparative Example 1-
The differential transmission cable of Comparative Example 1 will be described with reference to FIG. This differential transmission cable is a conventional type 1 cable.
First, the signal lines up to two cores (4 , 4) were manufactured in the same manner as in Example 1. Next, the signal wire 2 cores (4 , 4) and the horizontal drain wire (6) (silver plated annealed copper stranded wire having the same outer diameter of 0.38 mm as in Example 1) are connected in parallel. The outer conductor (5) is provided by spirally winding an alpet with a thickness of 0.015mm on the outside of the metal surface on the outside , and a PVC layer of thermoplastic resin is about 0.30mm as a jacket layer (8) on the outer periphery. The differential signal transmission cable (30) was manufactured by extruding to a thickness .
[0015]
-Comparative Example 2-
The differential transmission cable of the comparative example 2 is demonstrated using FIG.5 (b). This differential transmission cable is of the conventional type 2.
First, the signal lines up to two cores (4 , 4) were manufactured in the same manner as in Example 1. Next, one drain wire (6) (silver plated annealed copper stranded wire having the same outer diameter of 0.38 mm as in Example 1) is vertically attached to the central valley portion of the two signal wires (4 , 4) , Thereafter, in the same manner as in Comparative Example 1, the outer conductor (5) and the jacket layer (8) were provided, and the differential signal transmission cable (40) was manufactured.
[0016]
-Comparative Example 3-
A differential transmission cable of Comparative Example 3 will be described with reference to FIG. This differential transmission cable is a conventional type 3 cable.
First, the signal lines up to two cores (4 , 4) were manufactured in the same manner as in Example 1. Next, one drain wire (6) ( silver plated annealed copper stranded wire having the same outer diameter of 0.38 mm as in Example 1 ) is vertically attached to the central valley portion of the two signal wires (4 , 4). Three wires were twisted, and thereafter, the outer conductor (5) and the jacket layer (8) were provided in the same manner as in Comparative Example 1 to manufacture the differential signal transmission cable (50) .
[0017]
Characteristic test
The differential transmission cables of Example 1 and Comparative Examples 1 to 3 ( conventional 1 to 3 ) were tested for differential characteristic impedance, differential propagation delay time, and eye pattern. The differential characteristic impedance and the differential propagation delay time were measured using a TDR measuring instrument connected to a dedicated jig made by us using a sample with a cable length of 1 m. The eye pattern was measured using a pulse generator and an oscilloscope, connected to a dedicated jig made by our company with a cable length of 5 m, and transmitting a differential signal of 1 Gbps and 0.5 Vp-p . The results are shown in the following Table 1 and the eye pattern measurement chart of FIG.
[0018]
[Table 1]
[0019]
As is clear from the results of Table 1 above, the differential transmission cable of the present invention has a good balance of characteristic impedance in the differential pair, a small differential propagation delay time difference, and a small inward skew. On the other hand, in the conventional type 1 and type 2, the balance of characteristic impedance in the differential pair is lost, the differential propagation delay time difference is increased, and inward skew is generated. The conventional type 3 has a good balance of characteristic impedance in the differential pair, but the inward skew is large because the physical lengths of the two signal lines are not equal.
[0020]
Further, as is apparent from the eye pattern measurement results of FIG. 4, the eye pattern of the differential transmission cable of the present invention has no skew, has less “rounding” of the waveform (the rise / fall of the waveform is steep), and the opening. It was a good waveform with a sufficient rate.
On the other hand, the conventional 1 type and 3 type eye patterns are skewed, and as a result, the eyes are closed. Furthermore, the conventional 1 type, 2 type, and 3 type eye patterns have a large waveform “round” (cause of reducing the aperture ratio), and are not good waveforms.
[0021]
【The invention's effect】
In the differential signal transmission cable of the present invention, the drain line bites into the soft low-density insulating layer of the signal line by vertically attaching the drain line to a predetermined portion on the metal tape layer of the conductive tape wound as the outer conductor, The balance of characteristic impedance in the differential pair is improved without being crushed unevenly. In addition, by holding the vertically attached drain wire with a synthetic resin tape and making sure that it adheres firmly to the metal surface of the outer conductor (5) , stable grounding is ensured, and the potential between the drain wire in the differential pair Are equivalent, and good signal transmission characteristics can be obtained. Further, since the physical lengths of the two signal lines are always equal, inward skew does not occur. Further, the finished outer diameter (short diameter) can be made smaller than the conventional type 3 twist type. In addition, workability and terminal processability were improved. Furthermore, since the manufacture of the cable is relatively easy, it is possible to cope with the conventional equipment. Therefore, the present invention has a great effect of contributing to the industry.
[Brief description of the drawings]
FIG. 1 is a cross-sectional structure diagram of a differential signal transmission cable according to an embodiment (Example) of the present invention.
FIG. 2 is a cross-sectional structural view showing another embodiment of the differential signal transmission cable of the present invention. FIG. 2 (a) shows the differential signal transmission cable of Example 2, and FIGS. ) Are dual drain type differential signal transmission cables of Examples 3 and 4, respectively.
3 is a sectional view of a differential signal transmission cable according to a fifth embodiment of the present invention.
FIG. 4 is a chart showing eye pattern measurement results of a differential signal transmission cable.
5A and 5B are cross-sectional structural views showing an embodiment of a conventional differential signal transmission cable. FIG. 5A is a conventional differential signal transmission cable of type 1 (Comparative Example 1), and FIG. A differential signal transmission cable of type 2 (Comparative Example 2), and FIG. 5C shows a differential signal transmission cable of conventional type 3 (Comparative Example 3).
[Explanation of symbols]
1 Central conductor 2 Low density insulating layer 3 Skin layer 4 Signal line 5 External conductor (conductive tape)
6 the drain line 7 tape wrapping plastic tape layer 8 jacket layer 9, 9a, 9b, 9c terminal excellent formability differential signal transmission cable 10 terminal excellent formability differential signal transmission cable

Claims (4)

Two signal wires (4, 4) in which the signal conductor (4), which is provided with a low-density insulating layer (2) and a skin layer (3) in sequence on the outer periphery of the center conductor (1), is placed in parallel. An outer conductor (5) is provided on the outer periphery of the outer periphery of the outer conductor (5) so as to surround the conductive tape having an adhesive layer provided on a part of the metal surface of the conductive tape. Attached to the outer periphery of the drain wire (6) and the outer conductor (5), a synthetic resin tape provided with an adhesive layer on one side of the resin tape is wound to provide a press-wound synthetic resin tape layer (7), Furthermore, a differential signal transmission cable (9) formed by covering the outer periphery with a jacket layer (8),
The conductive tape is made of a metal laminate tape, a metal vapor-deposited tape or a metal tape, and the outer conductor (5) is formed by being spirally wound or vertically attached with the adhesive layer on the metal surface facing outside, and the drain wire (6) Is vertically attached to one or both of the central outer portion and the lateral outer portion of the two signal wires (4, 4) outside the outer conductor (5), and is in close contact with the outer conductor (5) by the synthetic resin tape. Thus, the differential signal transmission cable (9) excellent in terminal processability , characterized by being wound with the adhesive layer facing outward . The differential signal transmission cable (9) excellent in terminal workability according to claim 1, wherein the thickness (t) of the conductive tape is 0.010 mm ≤ t ≤ 0.050 mm. The differential signal transmission cable (9) excellent in terminal processability according to claim 1 or 2, wherein the thickness (u) of the synthetic resin tape is 0.004 mm ≤ u ≤ 0.030 mm. The differential signal transmission cable excellent in terminal processability according to any one of claims 1, 2, and 3. (9) Differential signal transmission cable with excellent terminal processability, characterized by aligning and fusing (Ten) .