JP2014143065A - Cable for differential signal transmission and connection method to circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cable for a differential signal transmission capable of providing stable electrical characteristic for each product, and to provide a connection method to a circuit board.SOLUTION: A pair of signal line conductors 11 are inserted into an insulator 12 at an opposite side against a side facing each other in a body part 15a of a conductor for a ground 15 and a pair of insertion pins 15b are set for fixing the body part 15a to an external conductor 13. Therefore, calking force by conventional calking works is not loaded to the insulation 12. The elastic deformation of the insulation 12 can be prevented, a distance between the signal wire conductors 11 can be set as per design dimensions, and stable electrical characteristic for each product can be obtained. Because the insertion pins 15b are arranged as a pair corresponding to the pair of signal line conductors 11, the external conductor 13 is fixed without jolting of the body part 15a while preventing electrical characteristic from being unstable.

Description

  The present invention relates to a differential signal transmission cable that includes a pair of signal line conductors and transmits a differential signal whose phase is inverted by 180 degrees and a method for connecting the same to a circuit board.

  Conventionally, in devices such as servers, routers, and storage products that handle high-speed digital signals of several Gbit / s or more, differential interface standards such as LVDS (Low Voltage Differential Signal) have been adopted. Differential signals are transmitted between the circuit boards using a differential signal transmission cable. The differential signal has a feature of high resistance to external noise while realizing a low system power supply voltage.

  The differential signal transmission cable includes a pair of signal line conductors, and a positive signal and a negative signal whose phases are inverted by 180 degrees are transmitted to the signal line conductors. The potential difference between these two signals becomes the signal level. For example, if the potential difference is positive, the signal level is recognized as “High”, and if it is negative, the signal level is recognized as “Low”. ing.

  As a differential signal transmission cable for transmitting such a differential signal, for example, a technique described in Patent Document 1 is known. The differential signal transmission cable described in Patent Document 1 includes a pair of signal line conductors arranged in parallel at predetermined intervals, and each of these signal line conductors is covered with an insulator. That is, the signal line conductors are held in parallel at predetermined intervals by the insulator. The periphery of the insulator is covered with a sheet-like outer conductor, and the periphery of the outer conductor is covered with a sheath as a protective skin.

  Then, the signal line conductors and a part of the outer conductor are exposed to the outside by sequentially stripping the longitudinal ends of the differential signal transmission cable. A metal shield connection terminal is connected to the exposed portion of the outer conductor by caulking. The shield connection terminal includes a plate-like metal and a solder connection pin integrally formed with the plate-like metal, and the plate-like metal is plastically deformed following the shape of the external conductor when caulking. Thus, the external conductor and the shield connection terminal are electrically connected, and the external conductor is electrically connected to the ground pad of the circuit board via the shield connection terminal.

JP 2012-099434 A (FIGS. 1 and 2)

  According to the differential signal transmission cable described in the above-mentioned Patent Document 1, the heat of the iron tip used in the solder connection work [about 350 ° C.] as compared with the case where the outer conductor is directly solder-connected to the ground pad. Is difficult to be transmitted to the external conductor, whereby the insulator can be prevented from being deformed or melted by heat. However, when the shield connection terminal is caulked along the shape of the outer conductor, the insulator inside the outer conductor is elastically deformed by the caulking force, and thus each signal line conductor further inside the insulator. Manufacturing problems can occur where the distance between them changes and does not match the design dimensions. This may cause a problem that the electrical characteristics of the differential signal transmission cable vary from product to product.

  An object of the present invention is to provide a differential signal transmission cable capable of obtaining stable electrical characteristics for each product and a method for connecting the same to a circuit board.

  In one aspect of the present invention, a pair of signal line conductors, an insulator provided around the signal line conductor, an external conductor provided around the insulator, and a longitudinal end of the signal line conductor are formed. A signal pad connection portion connected to the signal pad of the circuit board, a main body portion connected to the external conductor, and a ground conductor having a ground pad connection portion connected to the ground pad of the circuit board, A pair of insertion fixing parts for fixing the main body part to the outer conductor, wherein the main body part is inserted into the insulator on the opposite side to the side where the pair of signal line conductors face each other. Is provided.

  In another aspect of the present invention, a cable assembly preparation for preparing a cable assembly including a pair of signal line conductors, an insulator provided around the signal line conductor, and an external conductor provided around the insulator A circuit board preparation step for preparing a circuit board on which a signal pad and a ground pad are provided; a main body portion connected to the external conductor; and a ground pad connection portion connected to the ground pad, The ground is provided with a pair of insertion fixing parts for fixing the main body part to the external conductor, and the part is inserted into the insulator on the opposite side to the side where the pair of signal line conductors face each other. A ground conductor preparation step for preparing a conductor, and a signal connected to the signal pad at a longitudinal end of the signal line conductor A connecting portion forming step for forming a pad connecting portion; a ground conductor fixing step for fixing the ground conductor to the cable assembly by inserting the insertion fixing portion into the insulator; and the signal pad connecting portion and the ground. And a connection step of electrically connecting the pad connection portion so as to face the signal pad and the ground pad, respectively.

  In another aspect of the invention, the insertion fixing portion has a wire shape extending in a direction intersecting with the longitudinal direction of the signal line conductor.

  In another aspect of the present invention, a length dimension of the insertion fixing portion is a length dimension penetrating the insulator, and a distal end side of the insertion fixing portion that penetrates the insulator is folded.

  In another aspect of the present invention, the insertion fixing portion has a plate shape extending from the main body portion toward the signal line conductor.

  In another aspect of the present invention, the arrangement angle of the pair of insertion fixing portions with respect to the main body portion is different.

  In another aspect of the present invention, the surface roughness of the insertion fixing portion is made rougher than the surface roughness of other portions of the ground conductor.

  In another aspect of the present invention, the insertion position of the insertion fixing portion with respect to the insulator is between the signal line conductor and the outer conductor, and is closer to the outer conductor than an intermediate point between the two. It is.

  According to the present invention, a pair of signal lines are inserted into the insulator on the opposite side of the opposite side of the pair of signal line conductors into the main body of the ground conductor, and the pair of plugs for fixing the main body to the outer conductor. Since the fixing portion is provided, the crimping force by the conventional crimping process is not applied to the insulator. Accordingly, it is possible to suppress the insulator from being elastically deformed, and as a result, the distance between the signal line conductors can be set to the design dimension. Therefore, stable electrical characteristics can be obtained for each product. Further, since the pair of insertion fixing portions are provided corresponding to the pair of signal line conductors, the main body portion can be fixed to the external conductor without rattling while preventing the electrical characteristics from becoming unstable.

It is a perspective view which shows the connection structure of the cable for differential signal transmission which concerns on 1st Embodiment, and a circuit board. It is A arrow directional view of FIG. It is sectional drawing of the cable for differential signal transmission corresponding to the part in which an insertion pin is provided. (A), (b) is a perspective view explaining the detailed structure of the conductor for grounds. It is explanatory drawing explaining the assembly procedure of the cable for differential signal transmission of FIG. It is sectional drawing corresponding to FIG. 3 of the cable for differential signal transmission which concerns on 2nd Embodiment. It is a perspective view which shows the ground conductor which concerns on 2nd Embodiment. It is a perspective view which shows the reinforcement member provided corresponding to the ground conductor of FIG. It is sectional drawing corresponding to FIG. 3 of the cable for differential signal transmission which concerns on 3rd Embodiment. It is a perspective view which shows the conductor for ground concerning 3rd Embodiment. It is sectional drawing corresponding to FIG. 3 of the cable for differential signal transmission which concerns on 4th Embodiment. It is a perspective view which shows the conductor for ground concerning 4th Embodiment. It is a perspective view which shows the conductor for ground based on 5th Embodiment. It is a top view which shows the conductor for ground concerning 6th Embodiment. It is a top view which shows the conductor for ground concerning 7th Embodiment. It is a top view which shows the conductor for ground based on 8th Embodiment. It is a top view which shows the conductor for ground concerning 9th Embodiment.

  Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view showing a connection structure between a differential signal transmission cable and a circuit board according to the first embodiment, FIG. 2 is a view as seen from an arrow A in FIG. 1, and FIG. Sectional drawing of the cable for differential signal transmission corresponding to each is represented.

  As shown in FIGS. 1 to 3, the differential signal transmission cable 10 according to the first embodiment includes a pair of signal line conductors 11. A positive signal as a differential signal is transmitted to one of the signal line conductors 11, and a negative signal as a differential signal is transmitted to the other of the signal line conductors 11. It is like that. Each signal line conductor 11 is formed of, for example, an annealed copper wire (Tinned Annealed Copper Wire) whose surface is tin-plated, and each signal line conductor 11 is covered with an insulator 12.

  The insulator 12 is formed of, for example, foamed polyethylene (Foamed Poly-Ethylene) in order to give flexibility to the differential signal transmission cable 10, and its cross-sectional shape is formed in a substantially elliptical shape. The insulator 12 holds the signal line conductors 11 so as to be arranged in parallel at a predetermined interval, and the insulators 12 are arranged around the signal line conductors 11 so as to have substantially the same thickness. Here, the melting temperature of the foamed polyethylene which is the material of the insulator 12 is set to [110 ° C. to 120 ° C.].

  However, the insulator 12 is not limited to a substantially elliptical cross section as shown in the figure. For example, the insulator 12 may be an insulator having a circular cross section so as to cover each signal line conductor 11 separately. good. Furthermore, the cross-sectional shape of the insulator 12 may be formed of a pair of parallel lines having the same length and a pair of semicircular shapes, for example, substantially the same as a track in a track and field stadium.

  Most of the signal line conductors 11 along the longitudinal direction are arranged inside the insulator 12, and the longitudinal ends (left side in FIG. 1) of the signal line conductors 11 are exposed to the outside of the insulator 12. ing. The exposed portion of each signal line conductor 11 is a signal pad connection portion 11a, and the signal pad connection portion 11a is electrically connected to the signal pad 22 of the circuit board 20 by solder connection. Since the surface of each signal pad connecting portion 11a is tin-plated as described above, the solder wettability is improved, so that a good quality solder connection, that is, a solder fillet is formed. This is possible (see the shaded area in FIG. 2).

  Each signal pad connecting portion 11 a is formed in advance into a stepped shape before connecting the differential signal transmission cable 10 to the circuit board 20. Here, since the cross-sectional shape of each signal pad connecting portion 11a is a circular shape, stress concentration does not occur during forming. Therefore, each signal pad connecting portion 11a can be easily formed without breaking.

  An outer conductor 13 is provided around the insulator 12 in order to suppress the influence of external noise. The outer conductor 13 is formed of, for example, a sheet-like copper foil and covers the entire periphery of the insulator 12. However, the external conductor 13 is not limited to a copper foil, and may be another metal foil, or may be a braided sheet in which a thin metal wire such as an annealed copper wire is knitted.

  Most of the outer conductor 13 along the longitudinal direction is covered with the sheath 14, and the longitudinal end portion (left side in FIG. 1) of the outer conductor 13 is exposed to the outside of the sheath 14. Here, the sheath 14 is formed of, for example, heat-resistant PVC (Heat Resistant Polyvinyl Chloride), and functions as an outer skin that protects the differential signal transmission cable 10.

  4A and 4B are perspective views illustrating the detailed structure of the ground conductor.

  A ground conductor 15 formed in a predetermined shape by a metal plate material such as copper having excellent conductivity is attached to a portion exposed to the outside of the outer conductor 13, that is, an end portion of the outer conductor 13. As shown in FIG. 4, the ground conductor 15 includes a main body portion 15a, a pair of insertion pins 15b, and a pair of ground pad connection portions 15c.

  The main body portion 15 a is formed in a substantially arc shape in cross section by curving a substantially rectangular metal plate material in the same shape as the peripheral shape of the external conductor 13. Here, the main body portion 15a is curved in advance before the ground conductor 15 is attached to the external conductor 13, thereby preventing the insulator 12 and the like from being elastically deformed as before, and The conductor 13 can be reliably electrically connected.

  A pair of insertion pins 15b are integrally provided on the outer conductor 13 side of the main body portion 15a, that is, inside the curved main body portion 15a. Each insertion pin 15 b is disposed on both sides in the longitudinal direction of the main body portion 15 a and is formed in a wire shape extending in a direction intersecting with the longitudinal direction of each signal line conductor 11. Here, each insertion pin 15b constitutes an insertion fixing portion in the present invention.

  As shown in FIGS. 2 and 3, each insertion pin 15 b is inserted into an insulator 12 on the side opposite to the side where the signal line conductors 11 face each other, whereby the main body 15 a is connected to the outer conductor 13. It is fixed to. Here, each insertion pin 15 b is formed in a circular shape in cross section, and the tip side thereof is tapered so that it can be easily inserted into the insulator 12. However, the cross-sectional shape of each insertion pin 15b is not limited to a circle, and may be a polygonal shape such as a triangle or a quadrangle according to the strength required for each insertion pin 15b. Further, if the strength of each insertion pin 15b is sufficient, each insertion pin 15b can be formed thinner and the tapered shape can be omitted.

  Each insertion pin 15 b passes through the outer conductor 13 and is inserted into the insulator 12. Here, since the outer conductor 13 is formed of a sheet-like copper foil and each insertion pin 15b is formed in a tapered wire shape, the insertion resistance of each insertion pin 15b to the insulator 12 can be small. Therefore, in the process of attaching the ground conductor 15 to the external conductor 13, there is no problem that each insertion pin 15 b is bent and deformed, and the ground conductor 15 can be easily attached to the external conductor 13.

  As shown in FIG. 3, the insertion position of each insertion pin 15 b with respect to the insulator 12 is between each signal line conductor 11 and the outer conductor 13, and from an intermediate point between each signal line conductor 11 and the outer conductor 13. Is also close to the outer conductor 13. That is, the distance between each signal line conductor 11 and each insertion pin 15b along the long axis direction of the substantially elliptical shape of the differential signal transmission cable 10 is L1, and each insertion pin 15b and the external conductor 13 are connected to each other. When the distance between them is L2, it is inserted at a position satisfying the relationship of L1> L2. Further, the distal end side of each insertion pin 15b protrudes from the main body portion 15a by the height dimension H, and does not penetrate the insulator 12 when the ground conductor 15 is attached to the external conductor 13. (See FIG. 3).

  In this way, by setting the positional relationship and the protruding height relationship of each insertion pin 15b with respect to the insulator 12, each insertion pin 15b and each signal line are secured while securing the fixing strength of the ground conductor 15 to the outer conductor 13. The conductor 11 is as far away as possible. Therefore, the external noise is not affected on each signal line conductor 11 while preventing the ground conductor 15 from being detached from the external conductor 13.

  However, if the fixing strength of the ground conductor 15 with respect to the outer conductor 13 is sufficiently obtained, the protruding height of each insertion pin 15b from the main body portion 15a may be shortened. By shortening the protruding height of each insertion pin 15b, the distance between each insertion pin 15b and each signal line conductor 11 can be further increased. Accordingly, the relationship between the distance L1 and the distance L2 can be set to L1 <L2 in a range where the external noise does not affect each signal line conductor 11.

  A pair of ground pad connection portions 15c are integrally provided on both sides of the main body portion 15a in the longitudinal direction. Each ground pad connecting portion 15 c has a circular shape in cross section similar to each signal line conductor 11. Further, the length dimension of each ground pad connection portion 15c is set to be substantially the same as the length dimension of each signal pad connection portion 11a. Here, the cross-sectional shape of each ground pad connection portion 15c is circular, thereby preventing stress concentration during forming, as with each signal pad connection portion 11a.

  However, the cross-sectional shape of each ground pad connection portion 15c may be a square shape instead of the circular cross-sectional shape of each ground pad connection portion 15c. Moreover, you may provide the wide part (not shown) which raises the intensity | strength of the said base part in both base parts of each ground pad connection part 15c. Furthermore, the cross-sectional shape of each ground pad connection portion 15c is not limited to a circular shape or a square shape (quadrangle), but may be a triangular shape or a polygonal shape that is a pentagon or more. In this case, it is preferable to form one polygonal surface so as to be in surface contact with the ground pad 23.

  As shown in FIG. 2, each ground pad connection portion 15 c is arranged to be mirror-image symmetric with respect to each signal line conductor 11. In this way, by arranging the ground pad connection portions 15c so as to be mirror-image symmetrical with respect to the signal line conductors 11, the electric signals flowing through the signal line conductors 11 are balanced, and the differential signal transmission cable. 10 electrical characteristics are stabilized.

  As shown in FIG. 1, the tip of each ground pad connection portion 15c is electrically connected to the ground pad 23 of the circuit board 20 by solder connection. Here, the surface of each ground pad connection portion 15c is subjected to tin plating in the same manner as each signal pad connection portion 11a. Therefore, the solder wettability is improved, and a high-quality solder connection, that is, a solder fillet can be formed (see the shaded portion in FIG. 2).

  Each ground pad connection portion 15c is formed in a stepped shape in advance like the signal pad connection portions 11a before connecting the differential signal transmission cable 10 to the circuit board 20. These forming operations can be easily performed simultaneously, and as a result, the workability of solder connection to the signal pads 22 and the ground pads 23 of the circuit board 20 is improved.

  As shown in FIGS. 1 and 2, the signal pad connection portions 11 a and the ground pad connection portions 15 c are substantially overlapped when viewed from the side of the differential signal transmission cable 10. This suppresses deterioration of electrical characteristics in the high frequency range (Ghz band), that is, deterioration of characteristic impedance and skew characteristics.

  As shown in FIGS. 1 and 2, the circuit board 20 to which the differential signal transmission cable 10 is electrically connected includes a resin board main body 21. The signal pad 22 and a pair of ground pads 23 are formed. Each signal pad 22 and each ground pad 23 are arranged in a line corresponding to each signal pad connection portion 11 a and each ground pad connection portion 15 c of the differential signal transmission cable 10.

  Each signal pad 22 is electrically connected to a pair of signal lines 24 formed on the surface portion 21 a of the substrate body 21, and a differential signal is transmitted through each signal line 24. On the other hand, each ground pad 23 is electrically connected to one end portion of a through hole 25 penetrating from the front surface portion 21a of the substrate body 21 toward the back surface portion 21b. The other end of each through hole 25 is electrically connected to the entire ground 26 formed on the back surface 21b.

  Here, each signal pad 22, each ground pad 23, each signal line 24, and the entire surface ground 26 are simultaneously formed on the front surface portion 21a and the back surface portion 21b of the substrate body 21 together with other circuit patterns (not shown). It has become so.

  Next, a method for connecting the differential signal transmission cable 10 formed as described above to the circuit board 20 will be described in detail with reference to the drawings.

  FIG. 5 is an explanatory diagram for explaining an assembly procedure of the differential signal transmission cable of FIG.

[Cable assembly preparation process]
First, as shown in FIG. 5, a cable assembly CA manufactured in a separate manufacturing process is prepared. Here, the cable assembly CA is a pair of signal line conductors 11 arranged in parallel at a predetermined interval, an insulator 12 provided around the signal line conductor 11, and an external conductor 13 provided around the insulator 12. And a sheath 14 provided around the outer conductor 13, and indicates a state of a subassembly in which the ground conductor 15 is not attached.

[Circuit board preparation process]
Next, as shown in FIGS. 1 and 2, the circuit board 20 manufactured in a different manufacturing process, that is, each signal pad 22, each ground pad 23, each signal line 24, each through hole 25, and the entire ground 26. A circuit board 20 on which other circuit patterns are formed is prepared.

[Ground conductor preparation process]
Furthermore, as shown in FIG. 4, a ground conductor 15 manufactured in another manufacturing process is prepared. That is, it has a main body portion 15a connected to the external conductor 13 and a pair of ground pad connection portions 15c, and the main body portion 15a has an insulator located on the side opposite to the side on which the pair of signal line conductors 11 are opposed. 12, a ground conductor 15 provided with a pair of insertion pins 15b for fixing the main body 15a to the external conductor 13 is prepared.

  The above-mentioned [Cable Assembly Preparation Step], [Circuit Board Preparation Step], and [Ground Conductor Preparation Step] are manufactured in separate manufacturing steps, and the order may be changed.

[Connection part forming process]
After the cable assembly CA, the circuit board 20 and the ground conductor 15 are prepared, as shown in FIG. 5, a process of sequentially stripping the longitudinal ends of the cable assembly CA is performed. Specifically, the insulator 12 and the external conductor 13 are removed by a predetermined length from the longitudinal end of the cable assembly CA, and the longitudinal end of each signal line conductor 11 is exposed. Thereby, each signal pad connection part 11a electrically connected to each signal pad 22 (refer FIG. 1) of the circuit board 20 is formed. Further, the outer conductor 13 is exposed by removing the sheath 14 by a predetermined length from the longitudinal end of the outer conductor 13. Thereby, a connection part formation process is completed. Here, the length of the exposed portion of the external conductor 13 is adjusted to the length dimension along the short direction of the main body portion 15 a of the ground conductor 15.

[Ground conductor fixing process]
Next, as shown by an arrow M <b> 1 in FIG. 5, the ground conductor 15 is allowed to face the portion where the external conductor 13 is exposed by stripping. At this time, the distal end side of each insertion pin 15 b is made to face the external conductor 13 from one side (upper side in the drawing) along the minor axis direction of the substantially elliptical shape of the external conductor 13. Then, the ground conductor 15 is positioned on the external conductor 13 so that the direction in which each signal line conductor 11 extends and the direction in which each ground pad connection portion 15 c extends are matched. Thereafter, the insertion pin 15 b is inserted into the insulator 12 via the external conductor 13 by pressing the main body portion 15 a of the ground conductor 15 toward the external conductor 13 with a predetermined pressure. Thereby, the differential signal transmission cable 10 is completed.

  Here, since the insertion pins 15b are respectively arranged on both sides in the longitudinal direction of the main body portion 15a, the main body portion 15a of the ground conductor 15 is stable without rotating and rotating relative to the external conductor 13. The outer conductor 13 is attached under the state.

[Connection process]
Next, the signal pad connection portions 11a and the ground pad connection portions 15c of the completed differential signal transmission cable 10 are collectively formed into a stepped shape. Then, the formed signal pad connection portions 11a and the ground pad connection portions 15c are respectively brought into contact with the signal pads 22 and the ground pads 23 of the circuit board 20, and a total of four places are connected to a connecting jig (solder). Electrically connect with a trowel etc. Thereby, a connection process is completed and the connection operation | work to the circuit board 20 of the cable 10 for differential signal transmission is complete | finished.

  Here, since the tip portions of the signal pad connecting portions 11a and the ground pad connecting portions 15c are electrically connected, the heat of the connecting jig (for example, 200 ° C. to 400 ° C.) is difficult to be transmitted to the insulator 12. Yes. Therefore, the insulator 12 is not melted by the heat generated at the time of connection. However, the connection jig used for electrical connection is not limited to a soldering iron, and other connection jigs such as laser welding can also be used.

  As described above in detail, according to the differential signal transmission cable 10 and the connection method thereof to the circuit board 20 according to the first embodiment, the pair of signal line conductors 11 are connected to the main body portion 15a of the ground conductor 15. Are respectively inserted into the insulators 12 on the opposite side to the opposite side, and provided with a pair of insertion pins 15b for fixing the main body portion 15a to the outer conductor 13, the conventional caulking process is applied. The fastening force is not applied to the insulator 12. Therefore, it is possible to suppress the insulator 12 from being elastically deformed, and as a result, the distance between the signal line conductors 11 can be made as designed. Therefore, stable electrical characteristics can be obtained for each product. In addition, since a pair of insertion pins 15b are provided corresponding to the pair of signal line conductors 11, it is possible to fix the main body portion 15a to the external conductor 13 without rattling while preventing the electrical characteristics from becoming unstable. it can.

  Next, a second embodiment of the present invention will be described in detail with reference to the drawings. Note that portions having the same functions as those of the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  6 is a cross-sectional view corresponding to FIG. 3 of the differential signal transmission cable according to the second embodiment, FIG. 7 is a perspective view showing the ground conductor according to the second embodiment, and FIG. The perspective view which shows the reinforcement member provided corresponding to the conductor for ground of this is each represented.

  As shown in FIGS. 6 to 8, the differential signal transmission cable 30 according to the second embodiment includes the structure of the ground conductor 31 and the reinforcing member 32 as compared with the first embodiment. The point is different. A pair of insertion pins (insertion fixing portions) 31a are integrally provided on the main body portion 15a of the ground conductor 31, and each insertion pin 31a corresponds to each insertion pin 15b of the first embodiment (see FIG. 3). The length dimension is set to be approximately twice that of. That is, each insertion pin 31 a is set to a length dimension that penetrates the outer conductor 13 and the insulator 12.

  On the other hand, the reinforcing member 32 is formed in a predetermined shape by a metal plate material such as copper like the ground conductor 31, and has a curved shape like the main body portion 15a. The reinforcing member 32 is arranged to face the ground conductor 31 so as to sandwich the outer conductor 13 from the minor axis direction. A pair of insertion holes 32a through which the insertion pins 31a are inserted are provided on both sides of the reinforcing member 32 in the longitudinal direction.

  In assembling the differential signal transmission cable 30, each insertion pin 31 a is inserted into the outer conductor 13 and the insulator 12, and the distal end side of each insertion pin 31 a is inserted into each insertion hole 32 a. Thereafter, as shown by an arrow M2 in FIG. 6, the front end side of each insertion pin 31a is folded back along the reinforcing member 32, whereby the ground conductor 31 and the reinforcing member 32 are attached to the external conductor 13. The Thereby, the differential signal transmission cable 30 is completed.

  Also in the second embodiment formed as described above, the same effects as those in the first embodiment described above can be achieved. In addition, in the second embodiment, the length dimension of each insertion pin 31a is the length dimension that penetrates the insulator 12, and the tip end side of each insertion pin 31a that penetrates the insulator 12 is folded back. Further, it is possible to reliably prevent the ground conductor 31 from being detached from the outer conductor 13 and to obtain more stable electrical characteristics. However, the reinforcing member 32 may be omitted. In this case, the distal end side of each insertion pin 31a may be bent and deformed along the external conductor 13. Since each insertion pin 31a has a thin wire shape, the insulator 12 is not deformed when each insertion pin 31a is bent and deformed.

  Next, a third embodiment of the present invention will be described in detail with reference to the drawings. Note that portions having the same functions as those of the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 9 is a sectional view corresponding to FIG. 3 of the differential signal transmission cable according to the third embodiment, and FIG. 10 is a perspective view showing the ground conductor according to the third embodiment.

  As shown in FIGS. 9 and 10, the differential signal transmission cable 40 according to the third embodiment is different in the structure of the ground conductor 41 from the first embodiment. A pair of insertion blades (insertion fixing portions) 41 a are integrally provided on the main body portion 15 a of the ground conductor 41. Each insertion blade 41 a is formed in a plate shape having a cutting edge on the tip side, and the cutting edge extends from the main body portion 15 a toward each signal line conductor 11. Further, the width direction of each insertion blade 41a is directed to the short axis direction of the substantially elliptical shape of the differential signal transmission cable 40. Accordingly, each insertion blade 41a is inserted into the insulator 12 from the direction indicated by the arrow M3 in the figure while cutting the outer conductor 13 and the insulator 12.

  Here, also in each insertion blade 41a, each signal line conductor 11 is inserted into the insulator 12 on the side opposite to the side facing each other. Further, even at the insertion position of each insertion blade 41 a with respect to the insulator 12, the external conductor is located between each signal line conductor 11 and the external conductor 13 and more than the intermediate point between each signal line conductor 11 and the external conductor 13. 13 is close to the position.

  In the third embodiment formed as described above, the same operational effects as those of the first embodiment described above can be obtained. In addition, in the third embodiment, a plate-like insertion blade 41a extending from the main body portion 15a toward each signal line conductor 11 is used, and the outer conductor 13 and the insulator 12 are inserted into the insulator 12 while being cut. Therefore, the protruding height can be made lower than that of each insertion pin 15b of the first embodiment. Therefore, the rigidity of each insertion blade 41a can be increased, and as a result, the yield can be further improved.

  Next, a fourth embodiment of the present invention will be described in detail with reference to the drawings. Note that portions having the same functions as those of the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 11 is a sectional view corresponding to FIG. 3 of the differential signal transmission cable according to the fourth embodiment, and FIG. 12 is a perspective view showing the ground conductor according to the fourth embodiment.

  As shown in FIGS. 11 and 12, the differential signal transmission cable 50 according to the fourth embodiment is different in structure of the ground conductor 51 from the first embodiment. A pair of insertion blades (insertion fixing portions) 51 a are integrally provided on the main body portion 15 a of the ground conductor 51. Each insertion blade 51 a is formed in a plate shape having a cutting edge on the tip side, and the cutting edge extends from the main body portion 15 a toward each signal line conductor 11. Further, the width direction of each insertion blade 51 a is directed to the longitudinal direction of the differential signal transmission cable 40. Accordingly, each insertion blade 51a is inserted into the insulator 12 from the direction indicated by the arrow M4 in the figure while cutting the outer conductor 13 and the insulator 12. That is, the width direction of each insertion blade 51a is orthogonal to the width direction of each insertion blade 41a of the third embodiment.

  Here, also in each insertion blade 51a, each signal line conductor 11 is inserted into the insulator 12 on the side opposite to the side facing each other. Further, even at the insertion position of each insertion blade 51 a with respect to the insulator 12, the external conductor is located between each signal line conductor 11 and the external conductor 13 and more than the intermediate point of each signal line conductor 11 and external conductor 13. 13 is close to the position.

  Also in the fourth embodiment formed as described above, the same operational effects as those of the third embodiment described above can be achieved.

  Next, a fifth embodiment of the present invention will be described in detail with reference to the drawings. Note that portions having the same functions as those of the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 13 is a perspective view showing a ground conductor according to the fifth embodiment.

  As shown in FIG. 13, the differential signal transmission cable 60 according to the fifth embodiment is provided with a ground conductor 61 that can connect a plurality of cable assemblies CA (three in the figure) together. Is different. The ground conductor 61 is formed by integrating three main body portions 15a in the longitudinal direction, and a pair of insertion pins 15b are integrally provided inside each main body portion 15a.

  In addition, four ground pad connection portions 15c are provided in each main body portion 15a. Of the four ground pad connection portions 15c, the two ground pad connection portions 15c inside each function as a common ground pad connection portion 15c, and are used for a pair of adjacent cable assemblies CA.

  In assembling the differential signal transmission cable 60, the ground conductor 61 faces each cable assembly CA from the direction indicated by the arrow M5 in the figure, as in the first embodiment, and each insertion pin 15b. Is inserted into the insulator 12 of each cable assembly CA. Here, in order to prevent crosstalk between the cable assemblies CA, the adjacent cable assemblies CA are not brought into contact with each other.

  Although not shown, the circuit board to which the differential signal transmission cable 60 is connected is formed corresponding to the six signal pad connection portions 11a and the four ground pad connection portions 15c as shown in FIG. Is used. That is, the circuit board corresponding to the differential signal transmission cable 60 includes six signal pads and four ground pads 23.

  Also in the fifth embodiment formed as described above, the same operational effects as those of the above-described first embodiment can be obtained.

  Next, a sixth embodiment of the present invention will be described in detail with reference to the drawings. Note that portions having the same functions as those of the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 14 is a plan view showing a ground conductor according to the sixth embodiment.

  As shown in FIG. 14, in the sixth embodiment, each insertion pin (insertion fixing portion) 15b provided in the main body portion 15a of the ground conductor 15 is relatively gentle as shown by a one-dot chain line in the drawing. The difference is that the angle of inclination α is different. That is, the arrangement angle of each insertion pin 15b with respect to the main body portion 15a is different, and the inclination direction of each insertion pin 15b is a direction in which each ground pad connection portion 15c extends.

  In the sixth embodiment formed as described above, the same operational effects as those of the first embodiment described above can be obtained. In addition to this, in the sixth embodiment, the pull-out strength of the ground conductor 15 with respect to the insulator 12 can be further improved, and as a result, more stable electrical connection between the ground conductor 15 and the external conductor 13 can be achieved. Is possible. However, it is desirable that the inclination angle of each insertion pin 15b be a relatively gentle inclination angle (for example, less than 5 °) in order to suppress an increase in insertion resistance to the insulator 12.

  Next, a seventh embodiment of the present invention will be described in detail with reference to the drawings. Note that portions having the same functions as those of the first and third embodiments described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 15 is a plan view showing a ground conductor according to the seventh embodiment.

  As shown in FIG. 15, in the seventh embodiment, compared to the third embodiment described above, a line segment extending from the main body portion 15 a and passing through each insertion blade (insertion fixing portion) 41 a (in the drawing) The difference is that each insertion blade 41a is provided with a relatively gentle inclination angle α ° with reference to the one-dot chain line). That is, the arrangement angle of each insertion blade 41a with respect to the main body portion 15a is different, and the inclination direction of each insertion blade 41a is a direction in which each ground pad connection portion 15c extends.

  Also in the seventh embodiment formed as described above, the same operational effects as those of the sixth embodiment described above can be achieved.

  Next, an eighth embodiment of the present invention will be described in detail with reference to the drawings. Note that portions having the same functions as those in the first and fourth embodiments described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 16 is a plan view showing a ground conductor according to the eighth embodiment.

  As shown in FIG. 16, in the eighth embodiment, a line segment extending in the width direction (left-right direction in the drawing) of each insertion blade (insertion fixing portion) 51a as compared with the above-described fourth embodiment ( A difference is that each insertion blade 51a is provided with a relatively gentle inclination angle α ° with reference to a dashed line in the figure. That is, the arrangement angle of each insertion blade 51a with respect to the main body portion 15a is different, and the inclination direction of each insertion blade 51a is a direction intersecting the direction in which each ground pad connection portion 15c extends.

  Also in the eighth embodiment formed as described above, the same operational effects as those of the above-described sixth embodiment can be obtained.

  Next, a ninth embodiment of the present invention will be described in detail with reference to the drawings. Note that portions having the same functions as those of the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 17 is a plan view showing a ground conductor according to the ninth embodiment.

  As shown in FIG. 17, in the ninth embodiment, as compared with the first embodiment described above, the surface roughness of each insertion pin (insertion fixing portion) 70 provided in the main body portion 15a of the ground conductor 15 is increased. The difference is that the surface roughness of the other portion of the ground conductor 15 is made rougher (shaded portion in the figure).

  Also in the ninth embodiment formed as described above, the same operational effects as those of the above-described first embodiment can be obtained. In addition, in the ninth embodiment, the pull-out strength of the ground conductor 15 with respect to the insulator 12 can be further improved, and as a result, more stable electrical connection between the ground conductor 15 and the external conductor 13 is achieved. Is possible. However, it is desirable that the surface roughness of each insertion pin 70 is not too rough in order to suppress an increase in insertion resistance to the insulator 12.

  It goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. For example, in each of the above embodiments, when each signal pad connection portion 11a and each ground pad connection portion 15c are solder-connected to each signal pad 22 and each ground pad 23, each step is formed in advance into a stepped shape. However, the present invention is not limited to this. For example, when each signal pad and each ground pad are formed at the end of the circuit board, the forming operation can be omitted. As a result, the manufacturing process can be simplified and the manufacturing cost can be reduced. In addition, since each signal pad connection portion and each ground pad connection portion can be made straight, it is possible to obtain more stable electrical characteristics.

  Further, in each of the above embodiments, the differential signal transmission cables 10, 30, 40, 50, 60 are electrically connected to the circuit board 20, and the connection work is completed under the state. Although shown, the present invention is not limited to this. For example, the connection portion between the circuit board and the differential signal transmission cable may be covered with a resin mold. In this case, since the metal portion can be protected from dust, moisture, etc., it becomes possible to maintain predetermined electrical characteristics over a long period of time.

  In each of the above embodiments, the ground conductors 15, 31, 41, 51, 61 are mounted on the external conductor 13 so as to be covered from above in the figure. Not only this but according to the space on the circuit board 20, you may make it mount | wear with the external conductor 13 so that it may cover from the downward direction (from the circuit board 20 side) in the figure.

DESCRIPTION OF SYMBOLS 10 Differential signal transmission cable 11 Signal line conductor 11a Signal pad connection part 12 Insulator 13 External conductor 15 Ground conductor 15a Body part 15b Insertion pin (insertion fixing part)
15c Ground pad connection portion 20 Circuit board 22 Signal pad 23 Ground pad 30 Differential signal transmission cable 31 Ground conductor 31a Insertion pin (insertion fixing portion)
40 Differential signal transmission cable 41 Ground conductor 41a Insertion blade (insertion fixing part)
50 Differential signal transmission cable 51 Ground conductor 51a Insert blade (insertion fixing part)
60 Cable for differential signal transmission 61 Ground conductor 70 Insertion pin (insertion fixing part)

Claims (14)

A pair of signal line conductors;
An insulator provided around the signal line conductor;
An outer conductor provided around the insulator;
A signal pad connecting portion formed at a longitudinal end of the signal line conductor and connected to a signal pad of a circuit board;
A grounding conductor having a main body connected to the external conductor and a ground pad connection connected to a ground pad of the circuit board;
With
In the main body,
The differential signal transmission, wherein the pair of signal line conductors are respectively inserted into the insulators on the opposite side to the opposite side, and a pair of insertion fixing parts for fixing the main body part to the outer conductor is provided. Cable. The differential signal transmission cable according to claim 1,
The differential signal transmission cable, wherein the insertion fixing portion has a wire shape extending in a direction intersecting with a longitudinal direction of the signal line conductor. The differential signal transmission cable according to claim 2,
The differential signal transmission cable, wherein a length dimension of the insertion fixing portion is a length dimension that penetrates the insulator, and a distal end side of the insertion fixing portion that penetrates the insulator is folded back. The differential signal transmission cable according to claim 1,
The differential signal transmission cable, wherein the insertion fixing portion has a plate shape extending from the main body portion toward the signal line conductor. In the differential signal transmission cable according to any one of claims 1 to 4,
A differential signal transmission cable in which an arrangement angle of the pair of insertion fixing portions with respect to the main body portion is different. In the differential signal transmission cable according to any one of claims 1 to 5,
The differential signal transmission cable, wherein a surface roughness of the insertion fixing portion is rougher than a surface roughness of other portions of the ground conductor. In the differential signal transmission cable according to any one of claims 1 to 6,
The insertion position of the insertion fixing portion with respect to the insulator is between the signal line conductor and the outer conductor, and is a position closer to the outer conductor than an intermediate point between them. cable. A cable assembly preparation step of preparing a cable assembly including a pair of signal line conductors, an insulator provided around the signal line conductor, and an external conductor provided around the insulator;
A circuit board preparation step of preparing a circuit board provided with a signal pad and a ground pad;
A main body portion connected to the external conductor; and a ground pad connection portion connected to the ground pad, wherein the main body portion has the pair of signal line conductors on a side opposite to a side facing each other. A ground conductor preparation step for preparing a ground conductor that is inserted into each insulator and provided with a pair of insertion fixing portions for fixing the main body portion to the outer conductor;
A connecting portion forming step for forming a signal pad connecting portion connected to the signal pad at a longitudinal end portion of the signal line conductor;
A ground conductor fixing step of inserting the insertion fixing portion into the insulator and fixing the ground conductor to the cable assembly;
A connection step of electrically connecting the signal pad connection portion and the ground pad connection portion so as to face the signal pad and the ground pad, respectively;
A method for connecting a differential signal transmission cable to a circuit board. In the connection method to the circuit board of the cable for differential signal transmission according to claim 8,
A method for connecting a differential signal transmission cable to a circuit board, wherein the insertion fixing portion has a wire shape extending in a direction crossing a longitudinal direction of the signal line conductor. In the connection method to the circuit board of the cable for differential signal transmission according to claim 9,
A method for connecting a differential signal transmission cable to a circuit board, wherein a length dimension of the insertion fixing portion is a length dimension penetrating the insulator, and a distal end side of the insertion fixing portion penetrating the insulator is folded back. In the connection method to the circuit board of the cable for differential signal transmission according to claim 8,
A method for connecting a differential signal transmission cable to a circuit board, wherein the insertion fixing portion is in a plate shape extending from the main body portion toward the signal line conductor. In the connection method to the circuit board of the cable for differential signal transmission of any one of Claims 8-11,
A method for connecting a differential signal transmission cable to a circuit board, wherein an arrangement angle of the pair of insertion fixing portions with respect to the main body portion is different. In the connection method to the circuit board of the cable for differential signal transmission of any one of Claims 8-12,
A method for connecting a differential signal transmission cable to a circuit board, wherein a surface roughness of the insertion fixing portion is made rougher than a surface roughness of other portions of the ground conductor. In the connection method to the circuit board of the cable for differential signal transmission of any one of Claims 8-13,
The insertion position of the insertion fixing portion with respect to the insulator is between the signal line conductor and the outer conductor, and is a position closer to the outer conductor than an intermediate point between them. How to connect the cable to the circuit board.

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