JP2019067518A - Coaxial flat cable - Google Patents

Abstract

To provide a coaxial flat cable using a coaxial cable large in internal conductor diameter, small in finish outer diameter, and exhibiting stable high frequency property.SOLUTION: In a coaxial flat cable 20 having a plurality of coaxial cables 10 arranged in parallel with a constant gap P, and a fixing tape 11 for unifying at least terminal parts 21 of the plurality of coaxial cables 10 from a single surface or double surface, the coaxial cable 10 has an internal conductor 1, a dielectric layer 2 arranged on an outer periphery of the internal conductor 1 and having a gap part 2A continuing in a longer direction, an external conductor 3 arranged on an outer periphery of the dielectric layer 2, and an insulation layer 4 arranged on an outer periphery of the external conductor 3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a coaxial flat cable, and more particularly, to a flat cable which is used in or between electronic devices such as liquid crystal televisions and servers, and which uses a coaxial cable suitable for propagation of high frequency signals.

  Flat cables are excellent in processability and flexibility, and are widely used as internal wiring materials and external wiring materials of electronic devices. In particular, flat cables using a plurality of coaxial cables have been proposed as flat cables suitable for propagation of high frequency signals. For example, Patent Document 1 proposes a flat cable in which a plurality of coaxial cables having an outer diameter of 0.15 to 0.35 mm are arranged in parallel and fixed to a laminate sheet. This flat cable uses a micro coaxial cable having a central conductor in which seven ultrafine wires with a diameter of 0.016 mm to 0.025 mm are twisted together.

  On the other hand, as described in Patent Document 2, in recent years, the information handled in the electronic device has been increasing, so it is required to further increase the capacity and speed of the coaxial cable that propagates such information as an electric signal. The high frequency of electrical signals is accelerating. However, as the frequency of the electrical signal increases, current concentrates on the surface of the inner conductor (in Patent Document 1, a plurality of ultrafine wires twisted together) (referred to as the skin effect), and the effective cross-sectional area of the inner conductor Decrease. Therefore, the electrical resistance (AC resistance) increases with the increase of the frequency of the electrical signal, and the conductor loss increases. In addition, it is also required to increase the line length of the coaxial cable, and the electric resistance (conductor resistance) is also increased by the increase of the length, so that the conductor loss is increased. As a method of suppressing the rise of the electrical resistance and preventing the increase of the conductor loss, a coaxial cable in which the outer diameter of the inner conductor is enlarged is considered, but the outer diameter of the coaxial cable becomes large and the specified pitch of the connector There is a problem of exceeding.

JP, 2006-222059, A JP, 2015-138750, A

  As described above, in the case of the micro coaxial cable as in Patent Document 1, there is a problem that the conductor loss is too large. In addition, the coaxial cable in which the outer diameter of the inner conductor is increased has a problem that it exceeds the desired connector pitch because the outer diameter is increased.

  The present invention has been made to solve the above problems, and an object thereof is a coaxial flat cable using a coaxial cable which has a large internal conductor diameter, a small finished outer diameter and stable high frequency characteristics. To provide. In particular, it is hard to be crushed at the time of manufacture (for example, at the time of heating compression by heat seal etc.) or at the time of wiring operation etc., and the change of the distance between the inner conductor and the outer conductor is suppressed, the characteristic impedance is stable, and the high frequency characteristics are stable. An object of the present invention is to provide a coaxial flat cable.

  (1) A coaxial flat cable according to the present invention comprises: a plurality of coaxial cables arranged in parallel at a constant interval; and a fixing tape for integrating at least terminal portions of the plurality of coaxial cables from one side or both sides In the coaxial flat cable, the coaxial cable includes an inner conductor, a dielectric layer having a longitudinally continuous void provided on the outer periphery of the inner conductor, and an outer provided on the outer periphery of the dielectric layer. At least a conductor and an insulating layer provided on the outer periphery of the outer conductor.

  According to the present invention, since the dielectric layer has the continuous void in the longitudinal direction, the dielectric constant can be reduced by the presence of the void. As a result, the outer diameter of the inner conductor can be increased without increasing the outer diameter of the coaxial cable, and the effective cross-sectional area of the inner conductor can be increased to suppress an increase in high frequency resistance (AC resistance). Furthermore, the dielectric layer having a void portion continuous in the longitudinal direction is more likely to be produced at the time of manufacturing (for example, when applying pressure such as heat sealing) or at the time of wiring operation as compared with a dielectric layer consisting of a foam layer not continuous in the longitudinal direction. Since it is hard to collapse and the distance between the inner conductor and the outer conductor does not change, the characteristic impedance can be stabilized and the high frequency characteristics can be stabilized.

  (2) In the coaxial flat cable according to the present invention, the dielectric layer is a hollow structure including an inner annular portion, an outer annular portion, and a connecting portion connecting the two, and the hollow structure is a fluorine resin. It is preferable to be composed of

  According to the present invention, since the hollow structure is excellent in the side pressure strength, it is difficult to be crushed at the time of manufacturing, at the time of wiring operation and the like, and high frequency characteristics can be stabilized. Further, for example, a fluorine-based resin such as PFA (ε2.1) has a dielectric constant smaller than that of polyethylene (ε 2.2 to 2.6) and the like, so that the high frequency transmission characteristics can be further improved. The dielectric constant can be reduced according to the porosity of the body.

  (3) In the coaxial flat cable according to the present invention, the inner conductor is a strand of one strand or two or more strands, and the outer diameter of the inner conductor is 0.1 mm or more. It is preferable to set it in the range of 4 mm or less, and to make the said individual coaxial cable into the range of 2.5 times or more and 10 times or less of the outer diameter of the said inner conductor.

  According to the present invention, even if the outer diameter of the inner conductor is increased within the above range, the outer diameter of each coaxial cable can be limited within the above range, so that the desired connector pitch is not exceeded, which is stable. A coaxial flat cable exhibiting excellent high frequency characteristics can be used without changing the existing connector.

  (4) In the coaxial flat cable according to the present invention, it is preferable that the insulating layer is a spiral winding of a polyester tape provided with an adhesive layer on one side.

  According to the present invention, since the insulating layer is a spirally wound polyester tape provided with an adhesive layer on one side, the finished outer diameter can be reduced.

  (5) In the coaxial flat cable according to the present invention, preferably, the fixing tape is a polyester film provided with an adhesive layer on one side.

  In the present invention, a polyethylene terephthalate film is preferred as the polyester film, and a polyester thermoplastic adhesive layer is preferred as the adhesive layer. In addition, by using a sufficiently thick fixing tape having a thickness of, for example, 0.03 mm or more and 0.1 mm or less, the fixing tape can be less susceptible to heat during heat bonding, and as a result, shrinkage is less likely to occur. Can be a coaxial cable of stable pitch. Such a fixing tape may be bonded to all of the longitudinal direction of the plurality of coaxial cables, or may be bonded to only both end portions in the longitudinal direction. By bonding the fixing tape to only both terminals, for example, the non-integral portion other than the terminal portion can be deformed, and the degree of freedom in wiring in the electronic device can be improved.

  According to the present invention, it is possible to provide a coaxial flat cable using a coaxial cable which has a large internal conductor diameter, a small finished outer diameter and stable high frequency characteristics. In particular, it is hard to be crushed at the time of manufacture (for example, at the time of heating compression by heat seal etc.) or at the time of wiring operation etc., and the change of the distance between the inner conductor and the outer conductor is suppressed, the characteristic impedance is stable, and the high frequency characteristics are stable. A coaxial flat cable can be provided.

  That is, by enlarging the internal conductor, the conductor loss decreases, and it is possible to provide a coaxial flat cable that can cope with the increase in the frequency of the electric signal and the lengthening of the line length of the internal wiring. In addition, by forming the dielectric layer in a hollow structure, a coaxial flat cable exhibiting stable high frequency characteristics with no change in characteristic impedance without crushing of the dielectric layer when passing through a heating roll can be obtained, for example, 10 GHz. It is also possible to use at high frequencies such as 25 GHz.

It is sectional drawing which shows an example of the coaxial flat cable which concerns on this invention. It is a sectional view showing an example of a coaxial cable. It is a whole perspective view of a coaxial flat cable, (A) is a form which integrated both sides of a coaxial cable with fixed tape, (B) is a form which integrated both sides of an end of a coaxial cable with fixed tape. . FIG. 2 is a cross-sectional view of the coaxial flat cable of Example 1;

  Embodiments of a coaxial flat cable according to the present invention will be described with reference to the drawings. The present invention includes inventions of the same technical concept as the embodiments described below and the embodiments described in the drawings, and the technical scope of the present invention is limited only to the description of the embodiments and the drawings. It is not a thing.

  The coaxial flat cable 20 according to the present invention, as shown in FIGS. 1 to 3, includes a plurality of coaxial cables 10 arranged in parallel at a constant interval P and at least terminal portions 21 of the plurality of coaxial cables 10. And a fixing tape 11 integrated from one side or both sides. The coaxial cable 10 includes the inner conductor 1, the dielectric layer 2 provided on the outer periphery of the inner conductor 1 and having the air gap 2A continuous in the longitudinal direction Y, and the outer provided on the outer periphery of the dielectric layer 2. At least the conductor 3 and the insulating layer 4 provided on the outer periphery of the outer conductor 3 are provided.

  In this coaxial flat cable 20, since the dielectric layer 2 has the air gap 2A continuous in the longitudinal direction Y, the dielectric constant can be reduced by the presence of the air gap 2A. As a result, the outer diameter of the inner conductor 1 can be increased without increasing the outer diameter of the coaxial cable 10, and the effective cross-sectional area of the inner conductor 1 can be increased to suppress an increase in high frequency resistance (AC resistance). . Furthermore, the dielectric layer 2 having the void portion 2A continuous in the longitudinal direction Y, as compared with the dielectric layer formed of a foam layer not continuous in the longitudinal direction Y, is produced at the time of manufacturing Since it is hard to be crushed at the time of work and the like, and the distance between the inner conductor 1 and the outer conductor 3 does not change, the characteristic impedance can be stabilized and the high frequency characteristics can be stabilized. As a result, it is possible to provide the coaxial flat cable 20 using the coaxial cable 10 having a large internal conductor diameter, a small finished outer diameter, and stable high frequency characteristics.

  Hereinafter, each component of the coaxial flat cable will be described.

(Internal conductor)
As shown in FIGS. 1 and 2, the inner conductor 1 is constituted by one strand extending in the longitudinal direction Y of the coaxial cable 10, or is constituted by twisting a plurality of strands. And constitute the central conductor of the coaxial cable 10. The type of the wire is not particularly limited as long as it is made of a highly conductive metal, but a metal conductor of good conductivity such as copper wire, copper alloy wire, aluminum wire, aluminum alloy wire, copper aluminum composite wire, or The thing in which the plating layer was given to those surfaces can be mentioned preferably. From the viewpoint of high frequency, copper wire and copper alloy wire are particularly preferable. As a plating layer, a solder plating layer, a tin plating layer, a gold plating layer, a silver plating layer, a nickel plating layer etc. are preferable. The cross-sectional shape of the strands is also not particularly limited, but the cross-sectional shape may be circular, substantially circular or square.

  The cross-sectional shape of the inner conductor 1 is also not particularly limited, but may be circular (including oval) or rectangular (including square, pentagon, hexagon, octagon, etc.). The outer diameter of the internal conductor 1 is desirably as large as possible so as to reduce the electrical resistance (AC resistance, conductor resistance), and may be, for example, about 0.1 mm to 0.4 mm. Specifically, it may be about AWG 28 to 36 (7 / 0.127 to 7 / 0.05), preferably AWG327 / 0.08 (outside diameter: about 0.24 mm) or the like.

  An insulating film (not shown) may be provided on the surface of the inner conductor 1 as necessary. Although the type and thickness of the insulating film are not particularly limited, those which can be favorably decomposed at the time of soldering are preferable, and for example, a thermosetting polyurethane film can be preferably used. AWG (American Wire Gauge) is a symbol known as a dimensional standard of a conductor, and is also called B & S (Brown and Sharp) Gauge.

(Dielectric layer)
As shown in FIGS. 1 to 3, the dielectric layer 2 is provided on the outer periphery of the internal conductor 1 and has a void 2A continuous in the longitudinal direction Y. The void 2A is provided continuously in the dielectric layer 2, but the form thereof may be round or rectangular, and is not particularly limited. In particular, in the hollow structure 2 (which may have the same reference numeral 2 as the dielectric layer) formed of the inner annular portion 2B, the outer annular portion 2C, and the connecting portion 2D that connects these, the void portion 2A is an inner ring. It is a cross-sectional form surrounded by the portion 2B, the outer annular portion 2C and the connecting portion 2D, and is preferable because it is excellent in the side pressure strength. Such a hollow structure 2 is not easily crushed during the manufacture of the coaxial cable 10 and the coaxial flat cable 20, the wiring operation of the coaxial flat cable 20, and the like, and the high frequency characteristics can be stabilized. The hollow structure 2 can be formed by extruding, for example, a PFA resin on the outer periphery of the internal conductor 1 traveling on the extrusion die. PFA is a copolymer of tetrafluoroethylene and perfluoroether. The thickness of each of the inner annular portion 2B, the outer annular portion 2C, and the connecting portion 2D is not particularly limited, but is, for example, in the range of about 0.01 mm to 0.05 mm, and the formed hollow structure 2 (dielectric layer The outer diameter of 2) is, for example, in the range of about 0.4 mm to 1.0 mm.

  The dielectric layer 2 is preferably made of, for example, a fluorine-based resin such as PFA (dielectric constant ε: 2.1). The fluorine-based resin has a dielectric constant smaller than that of a polyolefin resin such as polyethylene (dielectric constant ε: 2.2 to 2.6), so that high frequency transmission characteristics can be further improved. Furthermore, the dielectric constant can be reduced according to the void ratio of the above-described hollow structure 2. As an example, the outer diameter of the hollow structure 2 is, for example, 0.58 mm, and the ratio of the void 2A (void ratio) ) Can be reduced to about 1.5 to 1.65. The void ratio of the void portion 2A is preferably in the range of 20% to 60% with respect to the area of the entire dielectric layer (entire hollow structure).

  In such a dielectric layer 2, it is preferable to adopt a hollow structure having an air gap 2A capable of lowering the dielectric constant and enhancing the side pressure strength so as to suppress the collapse, and further, it can withstand heating pressure such as heat sealing. It is preferable to select a fluorine-based resin. Since the dielectric layer 2 having such a structure can lower the dielectric constant, the outer diameter of the inner conductor 1 can be increased without increasing the outer diameter of the coaxial cable 10, and the effective cross-sectional area of the inner conductor 1 can be increased. An increase in high frequency resistance (AC resistance) can be suppressed. Furthermore, the dielectric layer 2 having the void portion 2A continuous in the longitudinal direction Y, as compared with the dielectric layer formed of a foam layer not continuous in the longitudinal direction Y, is produced at the time of manufacturing Since it is hard to be crushed at the time of work and the like, and the distance between the inner conductor 1 and the outer conductor 3 does not change, the characteristic impedance can be stabilized and the high frequency characteristics can be stabilized.

(External conductor)
The outer conductor 3 is provided on the outer periphery of the dielectric layer 2 and may be a braided thin wire or wound horizontally, or an insulating tape with a metal layer (such as a polyethylene terephthalate film with a copper layer) ), Or a combination of both. In the example of FIG. 2, the thin wire transverse winding 3A is provided on the outer periphery of the dielectric layer 2 and the insulating tape 3B with a metal layer is provided to cover it, but the present invention is not limited thereto. The thickness of the outer conductor 3 is not particularly limited, but is, for example, in the range of about 0.01 mm to 0.15 mm.

(Insulating layer)
The insulating layer 4 is provided on the outer periphery of the outer conductor 3, and the material is not particularly limited as long as it has insulating properties. Preferably, as illustrated in FIG. 2, the insulating tape 4A provided with the adhesive layer 4B on one side can be spirally wound and configured, but is not limited to this form. As the adhesive layer 4B, various materials applied to the coaxial cable 10 can be used. For example, polyester-based thermoplastic adhesive resin can be preferably mentioned, and as the insulating tape 4A, polyethylene terephthalate Preferred examples include polyester films such as films and polyethylene terephthalate films. In particular, it is preferable to select a material having good adhesion to the fixing tape 11 described later, for example, when the adhesive layer constituting the fixing tape 11 is a polyester thermoplastic adhesive layer, the insulating layer 4 is also a polyester film. Is preferred.

  The thickness of the adhesive layer 4B is, for example, in the range of about 0.001 mm to 0.005 mm, and the thickness of the insulating tape 4A is, for example, in the range of about 0.004 mm to 0.01 mm. By providing such an insulating layer 4, the finished outer diameter of the coaxial cable 10 can be reduced to, for example, about 0.4 mm to 1.0 mm.

(Coaxial flat cable)
As shown in FIGS. 1 to 3, the coaxial flat cable 20 includes a plurality of coaxial cables 10 arranged in parallel at a constant interval P, and a fixing tape 11 for integrating the coaxial cables 10 from one side or both sides. Are configured to have Each coaxial cable 10 is preferably in the range of 2.5 times to 10 times the outer diameter (for example, 0.1 mm to 0.4 mm) of the inner conductor 1. Within this range, the outer diameter of each coaxial cable 10 can be limited within the above range, even if the inner conductor 1 is made thicker in the above outer diameter range. As a result, the coaxial flat cable 20 exhibiting stable and excellent high frequency characteristics can be used without changing the existing connector without exceeding the desired connector pitch. The coaxial cable 10 is as described above.

  The fixing tape 11 integrates at least the terminal portions 21 of the plurality of coaxial cables 10 from one side or both sides as shown in FIGS. 1 and 3. FIG. 3 (A) shows an embodiment in which both sides of the coaxial cable 10 are sandwiched by two fixing tapes 11 and integrated, and FIG. 3 (B) shows two fixing tapes 11 of both ends of the end portion 21 of the coaxial cable 10. It is a form integrated by sandwiching. Thus, the fixing tape 11 may be bonded to all the longitudinal directions Y of the plurality of coaxial cables 10, or may be bonded to only the end portions 21 on both sides in the longitudinal direction. By bonding the fixing tape 11 only to the terminal parts 21 on both sides, for example, the intermediate parts 22 other than the terminal parts on both sides can be deformed as a non-integral part, and the flexibility in wiring in the electronic device can be improved. Can. In the example shown in FIG. 3, two fixed tapes 11 are sandwiched and bonded from both sides and integrated, but one fixed tape 11 is folded back and is bonded and integrated from both sides. Alternatively, one fixing tape 11 may be bonded to one side only to be integrated.

  The fixing tape 11 is usually composed of a base material 11A and an adhesive layer 11B provided on one side of the base material 11A. The substrate 11A is not particularly limited, but polyester films such as polyethylene terephthalate and polyethylene naphthalate can be preferably used. From the viewpoint of peelability, a uniaxially stretched film is preferred. The thickness of the substrate 11A is arbitrarily selected in the range of about 0.025 mm to 0.1 mm. The adhesive layer 11B is also not particularly limited, but is preferably made of a material that can be attached with good adhesion to the insulating layer 4 to be attached. For example, a polyester-based thermoplastic adhesive resin layer can be preferably mentioned. By using a material that easily adheres to the insulating layer 4, heat and pressure conditions can be relaxed in the thermocompression bonding step of bonding the fixing tape 11 so as to sandwich the plurality of coaxial cables 10, and load on the coaxial cable 10. The external force can be reduced, and as a result, there is an advantage that deformation and crushing of the dielectric layer 2 having the void portion 2A can be further suppressed. The thickness of the adhesive layer is arbitrarily selected in the range of about 0.02 mm to 0.035 mm.

  By using a sufficiently thick one having a total thickness of, for example, about 0.03 mm to 0.1 mm, the fixing tape 11 can be made less susceptible to the thermal influence at the time of heat bonding in a heat sealing step or the like. Shrinkage hardly occurs, and a stable pitch of the coaxial cable 10 can be secured.

  The coaxial flat cable 20 thus obtained can increase the outer diameter of the inner conductor 1 without increasing the outer diameter of the coaxial cable 10, and increases the effective cross-sectional area of the inner conductor 1 to increase the resistance of the high frequency resistance (AC resistance). The increase can be suppressed. Furthermore, the characteristic impedance is stable and the high frequency characteristics are stable because the distance between the inner conductor 1 and the outer conductor 3 does not change because it is difficult to be crushed during manufacturing (for example, when applying heat sealing etc.) or during wiring work. It can be

  The representative electrical characteristics required for the coaxial cable 10 are as follows.

Propagation delay time (Td) = √ε / 0.3 (nS / m)
Relative transmission rate (V) = 100 / ε ε (%)
Characteristic impedance (Zo) = 60 / √ε · LnD / d (Ω)
Capacitance (C) = 55.63 ε / LnD / d (PF / m)
Where ε: relative permittivity of insulator (dielectric layer 2), D: outer diameter of insulator (dielectric layer 2) (inner diameter of outer conductor 3), d: outer diameter of conductor (outer diameter of inner conductor 1) And).

  From this, the transmission characteristics of the coaxial cable 10 involve the relative dielectric constant of the dielectric layer 2, the outer diameter of the inner conductor 1 and the outer diameter of the dielectric layer 2, and the relative dielectric constant is small. It can be understood that the transmission characteristics are improved, and the ratio and the variation greatly contribute to the outer diameter of the inner conductor 1 and the outer diameter of the dielectric layer 2. In particular, regarding the characteristic impedance and the capacitance, the relative dielectric constant of the dielectric layer 2 is small and the variation thereof is small, and the outer diameter of the inner conductor 1 and the outer diameter of the dielectric layer 2 (inner diameter of the outer conductor 3 And the like, and it can be understood that it is ideal that their shapes are formed into a more perfect circular cylinder.

  Hereinafter, the present invention will be more specifically described by way of examples. The present invention is not limited to the following examples.

Example 1
The coaxial flat cable 20 illustrated in FIG. 4 was produced. As the internal conductor 1, an AWG 32 (having an outer diameter of about 0.24 mm) in which seven silver-plated soft copper wires having a diameter of 0.08 mm are twisted is used. The dielectric layer 2 is formed by extruding a PFA resin (made by DuPont) at 350 ° C. with a die nipple for a hollow structure, and the void 2A is surrounded by the inner annular portion 2B, the outer annular portion 2C and the connecting portion 2D. A hollow structure in cross-sectional form was formed. In this hollow structure, the thickness of the inner annular portion 2B is 0.05 mm, the thickness of the outer annular portion 2C is 0.05 mm, and the thickness of the connecting portion 2D is 0.05 mm. The outer diameter of 2) was 0.60 mm, and the void ratio of the voids 2A was 30% with respect to the area of the entire dielectric layer (entire hollow structure). The dielectric constant ε was about 1.6.

  The outer conductor 3 was formed by winding around the outer periphery of the dielectric layer 2 at a pitch of 12 mm using a transverse wound shield machine using 38 tin-plated soft copper wires having a diameter of 0.05 mm to form transversely wound thin transversely wound wires 3A. Furthermore, a 0.004 mm thick polyethylene terephthalate film (insulation tape 3B with metal layer) on which a 0.008 mm thick copper layer is formed is cut into a width of 2.5 mm, and the copper layer is traversed using a tape winding machine. The thin wire was wound on the side of thin wire winding 3A of the winding and wound with 1/3. Next, a 0.004 mm thick polyester tape (insulating tape 4A) provided with a 0.001 mm thick polyester thermoplastic resin (adhesive layer 4B) on one side is cut into a width of 3.0 mm, and a tape winding machine Using the adhesive layer 4B on the outer conductor side and wound with a 1/3 wrap.

  Sixteen of the obtained coaxial cables 10 were prepared and arranged in parallel at a constant interval P of 1 mm, and then the entire surfaces from both sides were bonded and integrated with a fixing tape 11. The fixing tape 11 was prepared by cutting a polyethylene terephthalate film substrate having a thickness of 0.060 mm and provided with a polyester thermoplastic resin (adhesive layer) having a thickness of 0.035 mm on one side to a width of 25 mm.

Example 2
A coaxial flat cable was produced in the same manner as in Example 1 except that the void ratio was 55%. In the hollow structure having a porosity of 55%, the thickness of the inner annular portion 2B is 0.03 mm, the thickness of the outer annular portion 2C is 0.03 mm, and the thickness of the connecting portion 2D is 0.03 mm, The outer diameter of the hollow structure (dielectric layer 2) is 0.60 mm as in the first embodiment. The dielectric constant ε was about 1.39.

Comparative Example 1
A coaxial flat cable was produced in the same manner as in Example 1 except that the dielectric layer 2 was a foam layer having a minute air layer. The foamed layer was formed by extrusion molding of a foaming agent-containing polyethylene compound, the porosity of the foamed layer was 30%, and the dielectric constant ε was about 1.80.

Comparative Example 2
A coaxial flat cable was produced in the same manner as in Example 1 except that the dielectric layer 2 was a solid layer having no air gap. The solid layer was formed by extrusion of PFA, and the dielectric constant ε was about 2.05.

[Measurement and result]
(Presence or absence of crushing during processing and wiring and high frequency characteristics)
At the time of processing, heating (about 170 ° C.) and pressure (about 0.2 MPa) are applied when heat sealing the coaxial cable 10 with the fixing tape 11, but such processing deforms the sectional form of the coaxial cable 10 and propagates It was examined whether or not to change the delay time.

  The propagation delay time of the coaxial flat cable is evaluated by using the coaxial flat cable cut into a fixed length (for example, 1 m) as a sample, and measuring the impedance and propagation delay time of the sample connected to the measuring machine by TDR method did. The presence or absence of deformation such as crushing was estimated from the variation (SKEW) of the obtained propagation delay time. As a measuring instrument, a Tektronix DCA 8200 sampling oscilloscope (TDR module: 80E04) was used.

  As shown in the results of Table 1, in Examples 1 and 2, the characteristic impedance was stable, and the delay time difference (SKEW) was also small. On the other hand, Comparative Example 1 had a variation in delay time, and SKEW was also large. In Comparative Example 2, the characteristic impedance could not be adjusted, and the delay time was increased to deteriorate the high frequency characteristics.

  From the above results, the coaxial flat cable 20 has a large internal conductor diameter, a small finished outer diameter, and stable high frequency characteristics, and further, during manufacturing (for example, during heating and compression such as heat sealing) and wiring It was hard to be crushed at the time of operation etc., and the change of the distance between the inner conductor 1 and the outer conductor 3 was suppressed, and the characteristic impedance could be stabilized and the high frequency characteristics could be stabilized.

1 internal conductor 2 dielectric layer (hollow structure)
2A Air Gap 2B Inner Annulus 2C Outer Annulus 2D Connection 3 Outer Conductor 3A Fine Wire Horizontal Winding 3B Insulating Tape with Metal Layer 4 Insulating Layer 4A Insulating Tape 4B Adhesive Layer 10 Coaxial Cable 11 Fixing Tape 11A Base Material 11B Adhesive Layer 20 coaxial flat cable 21 terminal 22 middle part (part other than the terminal)
P pitch (distance)
Y longitudinal direction

Claims (6)

In a coaxial flat cable, comprising: a plurality of coaxial cables arranged in parallel at a constant interval; and a fixing tape for integrating at least end portions of the plurality of coaxial cables from one side or both sides.
The coaxial cable includes an inner conductor, a dielectric layer provided on the outer periphery of the inner conductor and having a longitudinally continuous void, an outer conductor provided on the outer periphery of the dielectric layer, and the outer conductor. A coaxial flat cable comprising at least an insulating layer provided on the outer periphery of the connector.   2. The hollow structure according to claim 1, wherein the dielectric layer is a hollow structure formed of an inner ring portion, an outer ring portion, and a connecting portion connecting the inner ring portion, the outer ring portion, and the connecting portion. Coaxial flat cable.   The inner conductor is a strand of one strand or two or more strands and the outer diameter of the inner conductor is in the range of 0.1 mm to 0.4 mm, and the individual coaxial The cable is in the range of 2.5 times to 10 times the outer diameter of the inner conductor. The coaxial flat cable according to claim 1 or 2.   The coaxial flat cable according to any one of claims 1 to 3, wherein the insulating layer is a spiral winding of a polyester tape provided with an adhesive layer on one side.   The coaxial flat cable according to any one of claims 1 to 4, wherein the fixing tape is a polyester film provided with an adhesive layer on one side. The coaxial flat cable according to any one of claims 1 to 5, wherein the thickness of the fixing tape is in the range of 0.03 mm to 0.1 mm.

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