JP5915553B2 - Differential signal transmission cable and connection method thereof to circuit board - Google Patents

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 connecting the shield connection terminal to the external conductor, the outer conductor is correctly positioned on the flat shield connection terminal before plastic deformation, and the crimping process is performed with the two held without shifting. It was necessary to do. Therefore, the assembly work of the differential signal transmission cable may be complicated. In addition, since the shield connection terminal is crimped along the shape of the outer conductor, the insulator inside the outer conductor is elastically deformed by the crimping force, thereby causing each signal line conductor further inside the insulator. The distance between the products varies from product to product, and the electrical characteristics of each product may become unstable.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a differential signal transmission cable capable of obtaining stable electrical characteristics by suppressing the occurrence of variations among products while improving assembly workability, and a method for connecting the same to a circuit board. Is to provide.

  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 ground conductor connected to the external conductor; A main body portion provided on the ground conductor; provided on the main body portion; provided on the main body portion; and an insertion fixing portion for fixing the main body portion to the outer conductor by being inserted into the insulator. An insertion guiding portion for guiding the insertion fixing portion to the insertion position of the insulator.

  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; and a main body portion connected to the outer conductor, wherein the main body portion is inserted into the insulator to fix the main body portion to the outer conductor. A ground conductor preparing step for preparing a ground conductor provided with an insertion fixing portion for guiding the insertion fixing portion to the insertion position of the insulator, and the insertion guiding portion for the external conductor Assembling the differential signal transmission cable by inserting the insertion fixing portion into the insulator and fixing the ground conductor to the outer conductor. Comprising a table assembly process, the signal line conductors and the ground conductors, and a connection step of electrically connecting each of said circuit board.

  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, 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 insertion guiding portion is provided with an inclined wall for guiding the outer conductor to the insertion guiding portion.

  In another aspect of the present invention, the main body portion is provided with a pair of insertion fixing portions, and the arrangement angles of the insertion fixing portions with respect to the main body portion are 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, an insertion fixing portion for fixing the main body portion to the external conductor by being inserted into the main body portion of the ground conductor, and for guiding the insertion fixing portion to a predetermined insertion position of the insulator. Since the insertion guide portion is provided, it is possible to eliminate the need for crimping while eliminating the need for accurate positioning as before. Therefore, the assembly workability of the differential signal transmission cable can be improved. In addition, since the conventional caulking force is not applied to the insulator, it is possible to suppress the insulator from being elastically deformed, and consequently to prevent the distance between the signal line conductors from varying from product to product. Thus, it is possible to obtain stable electrical characteristics for each product.

FIG. 3 is a perspective view showing a connection structure between the differential signal transmission cable and the circuit board according to the first embodiment. 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. FIG. 4 is a cross-sectional view corresponding to FIG. 3 of a differential signal transmission cable according to a second embodiment. FIG. 6 is a perspective view showing a ground conductor according to a second embodiment. FIG. 6 is a cross-sectional view corresponding to FIG. 3 of a differential signal transmission cable according to a third embodiment. FIG. 6 is a cross-sectional view corresponding to FIG. 3 of a differential signal transmission cable according to a fourth embodiment. FIG. 9 is a perspective view showing a ground conductor according to a fourth embodiment. FIG. 10 is a perspective view showing a ground conductor according to a fifth embodiment. FIG. 10 is a plan view showing a ground conductor according to a sixth embodiment. FIG. 12 is a plan view showing a ground conductor according to a seventh embodiment. FIG. 10 is a plan view showing a ground conductor according to an eighth embodiment. FIG. 10 is a partial cross-sectional view showing a ground conductor according to a ninth embodiment.

  Hereinafter, Embodiment 1 of the present invention will be described in detail with reference to the drawings.

  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 taken along an arrow A in FIG. 1, and FIG. 3 is a portion where an insertion pin is provided. Cross-sectional views of corresponding differential signal transmission cables are shown.

  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, a pair of insertion guide walls 15c, and a pair of ground pad connection portions 15d. In the drawing, the boundary between the main body portion 15a and each insertion guide wall 15c is indicated by a one-dot chain line.

  The main body 15 a is formed in a substantially U-shaped cross section by curving a substantially rectangular metal plate material in the same shape as the peripheral shape of the outer 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 connecting 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.

  The protrusion height of each insertion pin 15b from the main body portion 15a is set to h1, and the tip portion thereof is arranged at the lower end portion of each signal line conductor 11 in the schematic diagram. In other words, each insertion pin 15 b does not penetrate through the insulator 12 under the connection state of the ground conductor 15 to the external conductor 13.

  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. Thereby, it is possible to prevent the external noise from affecting each signal line conductor 11 while preventing the ground conductor 15 from being detached from the external conductor 13.

  Insertion guide walls 15c are provided on both longitudinal sides of the main body 15a. Each insertion guide wall 15c is formed by extending both longitudinal sides of the main body portion 15a, and is divided into a main body portion 15a and each insertion guide wall 15c with a dashed line in the figure as a boundary. Here, each insertion guide wall 15c constitutes an insertion guide portion in the present invention, and when connecting the ground conductor 15 to the external conductor 13, each insertion pin 15b is connected to a predetermined insertion position of the insulator 12 ( (See FIG. 3).

  When the ground conductor 15 is connected to the external conductor 13 on the side of each insertion pin 15b of each insertion guide wall 15c, the external conductor 13 comes into sliding contact as shown by a two-dot chain line in the figure. Here, the major axis dimension W1 of the outer conductor 13 is set to be slightly larger than the separation distance W2 of each insertion guide wall 15c (W1> W2). This prevents the ground conductor 15 from dropping from the external conductor 13 in the process of connecting the ground conductor 15 to the external conductor 13, thereby improving the assembly workability of the differential signal transmission cable 10. .

  The positional relationship between each insertion guide wall 15c and each insertion pin 15b is as follows. In the process of connecting the ground conductor 15 to the outer conductor 13, the outer conductor 13 is first connected to each insertion guide wall as shown by a two-dot chain line in the figure. The insertion pins 15b are in sliding contact with the guides 15c and are then brought into contact with the predetermined positions of the outer conductors 13 after being guided. That is, each insertion pin 15b is inserted into a predetermined insertion position of the insulator 12 via the outer conductor 13 simply by inserting the outer conductor 13 between the insertion guide walls 15c.

  Here, as shown in FIG. 2, with the differential signal transmission cable 10 electrically connected to the circuit board 20, there is a slight gap between each insertion guide wall 15 c and the circuit board 20. t is formed, which stabilizes the electrical characteristics of the differential signal transmission cable 10.

  Depending on the fixing strength required for the outer conductor 13 of the ground conductor 15, the protrusion height h1 of each insertion pin 15b can be lowered. In this case, the position where each insertion guide wall 15c is arranged can be moved upward in the figure, and as a result, the ground conductor 15 can be reduced in size and weight. Further, by shortening the protruding height h1 of each insertion pin 15b, the distance between each insertion pin 15b and each signal line conductor 11 can be further increased, so that external noise does not affect each signal line conductor 11. In the range, the relationship between the distance L1 and the distance L2 may be L1 <L2.

  As shown in FIG. 4, a pair of ground pad connection portions 15d are integrally provided on both sides in the longitudinal direction of the main body portion 15a. Each ground pad connecting portion 15d has a circular shape in cross section similar to each signal line conductor 11 (see FIG. 2). The length dimension of each ground pad connection portion 15d 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 15d 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 15d may be a square shape instead of the circular cross-sectional shape of each ground pad connection portion 15d. 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 15d. Furthermore, the cross-sectional shape of each ground pad connection portion 15d 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 desirable to form one polygonal surface so as to be in surface contact with the ground pad 23 (see FIG. 1).

  As shown in FIG. 2, each ground pad connection portion 15 d 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 15d 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 15d 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 15d 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 15d is formed into a stepped shape in advance like each signal pad connection portion 11a before the differential signal transmission cable 10 is electrically connected to the circuit board 20. . These forming operations can be easily performed at the same time, 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.

  Further, as shown in FIGS. 1 and 2, each signal pad connection portion 11a and each ground pad connection portion 15d are substantially overlapped when the differential signal transmission cable 10 is viewed from the side. 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 d 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 view for explaining the 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, a main body 15a connected to the outer conductor 13 of the cable assembly CA is provided, and the main body 15a is inserted with the insertion pin 15b for being inserted into the insulator 12 and fixing the main body 15a to the outer conductor 13. A ground conductor 15 provided with an insertion guide wall 15c for guiding the pin 15b to a predetermined insertion position of the insulator 12 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, each insertion guide wall 15c faces the outer conductor 13 so that the outer conductor 13 can enter between the insertion guide walls 15c. Then, by pressing the ground conductor 15 from one side (upper side in the figure) along the minor axis direction of the substantially elliptical shape of the outer conductor 13, the outer conductor 13 is guided by the insertion guide walls 15c, It approaches the tip of the insertion pin 15b.

  Thereafter, the grounding conductor 15 is further pressed toward the external conductor 13, whereby each insertion pin 15 b is inserted into a predetermined insertion position of the insulator 12 via the external conductor 13. Thereafter, the ground conductor 15 is further pressed, whereby the main body portion 15a is electrically connected to the external conductor 13, thereby completing the cable 10 for differential signal transmission.

  Here, in the step of fixing the ground conductor 15 to the cable assembly CA, the outer conductor 13 is stably held without being fluctuated by the insertion guide walls 15c and the main body portion 15a. There is no need to squeeze, and sufficient fixing strength is secured.

[Connection process]
Next, each signal pad connection portion 11a and each ground pad connection portion 15d of the completed differential signal transmission cable 10 are collectively formed into a stepped shape. Then, the formed tip portions of the signal pad connection portions 11a and the ground pad connection portions 15d face the signal pads 22 and the ground pads 23 of the circuit board 20, respectively. 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 15d are connected, the heat of the connecting jig (for example, 200 ° C. to 400 ° C.) is hardly transmitted to the insulator 12. Therefore, the insulator 12 is not melted by the heat generated at the time of connection. However, the connection jig used for connection is not limited to a soldering iron or the like, 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 insulator 12 is inserted into the main body portion 15a of the ground conductor 15. Since the insertion pin 15b for fixing the main body portion 15a to the outer conductor 13 and the insertion guide wall 15c for guiding the insertion pin 15b to a predetermined insertion position of the insulator 12 are provided, the conventional accurate The caulking process can be made unnecessary while positioning is unnecessary. Therefore, the assembly workability of the differential signal transmission cable 10 can be improved. Further, since the conventional caulking force is not applied to the insulator 12, it is possible to suppress the insulator 12 from being elastically deformed, and the distance between the signal line conductors 11 varies from product to product. Stable electrical characteristics can be obtained for each product.

  Next, Embodiment 2 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 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, and FIG. 7 is a perspective view showing the ground conductor according to the second embodiment.

  As shown in FIGS. 6 and 7, the differential signal transmission cable 30 according to the second embodiment differs from the first embodiment in the structure of the ground conductor 31. A pair of insertion blades (insertion fixing portions) 31 a are integrally provided on the main body portion 15 a of the ground conductor 31. Each insertion blade 31a is formed in a plate shape having a cutting edge on the distal end side, and the cutting edge extends from the main body portion 15a toward each signal line conductor 11 respectively. Each insertion blade 31 a is disposed substantially beside each signal line conductor 11 along the long axis direction of the differential signal transmission cable 30.

  Further, the width direction of each insertion blade 31 a is directed to the minor axis direction of the differential signal transmission cable 30. Accordingly, each insertion blade 31a is inserted into the insulator 12 from the direction indicated by the arrow M2 in the figure while cutting the outer conductor 13 and the insulator 12.

  Here, also in each insertion blade 31a, 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 31 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. That is, the distance between each signal line conductor 11 and the cutting edge of each insertion blade 31a along the long axis direction of the differential signal transmission cable 10 is L3, and the distance between the cutting edge of each insertion blade 31a and the external conductor 13 Is set at a position satisfying the relationship of L3> L4.

  In the process of connecting the ground conductor 31 to the external conductor 13, first, the external conductor 13 is guided by sliding contact with each insertion guide wall 15 c, and then each insertion blade 31 a is brought into contact with a predetermined position of the external conductor 13. It has become so. That is, each insertion blade 31a is inserted into the predetermined insertion position of the insulator 12 via the external conductor 13 only by inserting the external conductor 13 between the insertion guide walls 15c.

  However, if the fixing strength of the ground conductor 31 with respect to the outer conductor 13 is sufficiently obtained, the amount of cutting into the outer conductor 13 and the insulator 12 is reduced, and each insertion blade 31a is moved closer to the bottom of the main body portion 15a ( You may arrange | position to upper side in a figure. In this case, the distance between each insertion blade 31a and each signal line conductor 11 can be further increased, and the relationship between the distance L3 and the distance L4 is expressed as L3 <L4 in a range where external noise does not affect each signal line conductor 11. You can also

  In the second embodiment formed as described above, the same operational effects as those of the first embodiment described above can be obtained. In addition, in the second embodiment, a plate-like insertion blade 31a 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. Since it did in this way, compared with each insertion pin 15b of Embodiment 1, the protrusion height dimension can be made low. Therefore, the rigidity of each insertion blade 31a can be increased, and as a result, the yield can be further improved.

  Next, Embodiment 3 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 embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 8 is a cross-sectional view corresponding to FIG. 3 of the differential signal transmission cable according to the third embodiment.

  As shown in FIG. 8, the differential signal transmission cable 40 according to the third embodiment is different in structure of the ground conductor 41 from the first embodiment. The main body portion 15a of the ground conductor 41 is integrally provided with an insertion pin 41a having a height dimension h2 lower than the protruding height h1 (see FIG. 3) of each insertion pin 15b of the first embodiment (h2). <H1). Only one insertion pin 41a is provided corresponding to one signal line conductor 11 (here, the right side in the figure). The insertion position of the insertion pin 41a with respect to the insulator 12 is between one signal line conductor 11 and the external conductor 13 and one signal line conductor, as in the first embodiment (see FIG. 3). 11 and an intermediate point between the outer conductor 13 and the position closer to the outer conductor 13.

  Further, as the height h2 of the insertion pin 41a is lowered, each insertion guide wall 15c is moved upward in the figure as compared with the first embodiment. That is, each insertion guide wall 15c is disposed closer to the root of the insertion pin 41a than in the first embodiment. As described above, in the process of connecting the ground conductor 41 to the external conductor 13 by setting the positional relationship between the insertion pin 41a and each insertion guide wall 15c as described above, first, the external conductor 13 Each insertion guide wall 15c is slidably contacted and guided, and then the insertion pin 41a is brought into contact with a predetermined position of the outer conductor 13.

  Further, an inclined wall 41b is integrally provided on the opposite side (lower side in the drawing) of each insertion guide wall 15c to the main body portion 15a side. Each inclined wall 41b is arranged in a space formed on the side opposite to the main body portion 15a side of each insertion guide wall 15c by moving each insertion guide wall 15c upward in the drawing as described above. . Each inclined wall 41b is inclined to the opposite side (outside) from the outer conductor 13 side as it goes downward in the figure from each insertion guide wall 15c.

  Thereby, the separation distance W3 of each inclined wall 41b on the side (introduction side) into which the outer conductor 13 enters is larger than the separation distance W2 of each insertion guide wall 15c and the major axis dimension W1 of the outer conductor 13 (see FIG. 3). It is set (W3> W1> W2). That is, each inclined wall 41b guides the external conductor 13 between each insertion guide wall 15c as shown by a two-dot chain line in the figure when the ground conductor 41 is connected to the external conductor 13. .

  Also 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, since the inclined wall 41b for guiding the outer conductor 13 to the insertion guide wall 15c is provided on the insertion guide wall 15c, the assembly workability of the differential signal transmission cable 10 is improved. Can be improved. Moreover, since only one insertion pin 41a is provided, the shape of the ground conductor 41 can be simplified.

  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 in 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 fourth embodiment, and FIG. 10 is a perspective view showing the ground conductor according to the fourth embodiment.

  As shown in FIGS. 9 and 10, 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. Each insertion blade 51 a is disposed substantially beside each signal line conductor 11 along the long axis direction of the differential signal transmission cable 50.

  Further, the width direction of each insertion blade 51 a is directed to the longitudinal direction of the differential signal transmission cable 50. Accordingly, each insertion blade 51a is inserted into the insulator 12 while cutting the outer conductor 13 and the insulator 12 in the direction indicated by the arrow M3 in the drawing. That is, the width direction of each insertion blade 51a is orthogonal to the width direction of each insertion blade 31a of the second 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. Furthermore, 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 between each signal line conductor 11 and the external conductor 13. 13 is close to the position.

  Furthermore, an insertion guide wall (insertion guiding portion) 51b is provided on the opposite side of the main body portion 15a from the ground pad connection portion 15d side along the short direction, with a dashed line in the figure as a boundary. Also in this insertion guide wall 51b, when connecting the ground conductor 51 to the external conductor 13, each insertion blade 51a is guided to a predetermined insertion position (position shown in FIG. 9) of the insulator 12. .

  Thus, in the process of connecting the ground conductor 51 to the external conductor 13, first, the external conductor 13 is guided by sliding contact with the insertion guide wall 51 b, and then each insertion blade 51 a is brought into contact with a predetermined position of the insulator 12. It has become so. That is, each insertion blade 51 a is inserted into a predetermined insertion position of the insulator 12 by merely bringing the outer conductor 13 into sliding contact with the insertion guide wall 51 b.

  An inclined wall 51c is integrally provided on the opposite side of the insertion guide wall 51b from the main body portion 15a side. The inclined wall 51c is inclined so as to expand to the side (outside) opposite to the outer conductor 13 side as the distance from the insertion guide wall 51b increases. As a result, the inclined wall 51c guides the external conductor 13 toward the insertion guide wall 51b when the ground conductor 51 is connected to the external conductor 13, as in the third embodiment (see FIG. 8). ing.

  In the fourth embodiment formed as described above, the same operational effects as those of the first embodiment can be obtained. In addition, in the fourth embodiment, as in the second embodiment, the rigidity of each insertion blade 51a can be increased, and as a result, the yield can be further improved. As in the third embodiment, the assembling workability of the differential signal transmission cable 10 can be improved by the inclined wall 51c.

  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 in the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 11 is a perspective view showing a ground conductor according to the fifth embodiment.

  As shown in FIG. 11, the differential signal transmission cable 60 according to the fifth embodiment is different in that it includes a ground conductor 61 that can connect a plurality of cable assemblies CA (three in the figure) together. ing. The ground conductor 61 has three main body portions 15a aligned in the longitudinal direction, and a pair of insertion pins 15b (only one is shown in the figure) are integrally provided inside each main body portion 15a. Yes.

  Further, four insertion guide walls 15c are provided in each main body 15a. Of the four insertion guide walls 15c, the two insertion guide walls 15c inside each function as a common insertion guide wall 15c, and are used for a pair of adjacent cable assemblies CA.

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

  In assembling the differential signal transmission cable 60, the ground conductor 61 is pressed toward the external conductor 13 from the direction indicated by the arrow M4 in the figure, as in the first embodiment. 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 15d 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.

  In the fifth embodiment formed as described above, the same operational effects as those of the first embodiment described above 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 in the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 12 is a plan view showing a ground conductor according to the sixth embodiment.

  As shown in FIG. 12, 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 figure. The difference is that the inclination angle α ° is added. 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 15d 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, in the sixth embodiment, the fixing strength of the ground conductor 15 with respect to the insulator 12 can be further improved, and as a result, a more stable electrical connection between the ground conductor 15 and the external conductor 13 is achieved. It becomes 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 parts having the same functions as those in the first and second embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 13 is a plan view showing a ground conductor according to the seventh embodiment.

  As shown in FIG. 13, in the seventh embodiment, as compared with the second embodiment described above, a line segment extending from the main body portion 15a and passing through each insertion blade (insertion fixing portion) 31a (a chain line in the figure) ) Is used as a reference in that each insertion blade 31a is provided with a relatively gentle inclination angle α °. That is, the arrangement angle of each insertion blade 31a with respect to the main body portion 15a is different, and the inclination direction of each insertion blade 31a is a direction in which each ground pad connection portion 15d 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 parts having the same functions as those in the first and fourth embodiments 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 eighth embodiment.

  As shown in FIG. 14, in the eighth embodiment, as compared with the above-described fourth embodiment, a line segment (in the drawing) extending in the width direction (left and right direction in the drawing) of each insertion blade (insertion fixing portion) 51a. The difference is that each insertion blade 51a is provided with a relatively gentle inclination angle α ° with reference to a one-dot chain line). 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 15d extends.

  In the eighth embodiment formed as described above, the same operational effects as those of the sixth embodiment described above 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 in the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 15 is a partial sectional view showing a ground conductor according to the ninth embodiment.

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

  In the ninth embodiment formed as described above, the same operational effects as those of the first embodiment described above can be obtained. In addition, in the first embodiment, the fixing strength of the ground conductor 15 with respect to the insulator 12 can be further improved, and as a result, a more stable electrical connection between the ground conductor 15 and the external conductor 13 is achieved. It becomes 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 15d are solder-connected to each signal pad 22 and each ground pad 23, each 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 12 Insulator 13 External conductor 15 Ground conductor 15a Body 15b Insertion pin (insertion fixing part)
15c Insertion guide wall (insertion guide)
20 Circuit board 30 Differential signal transmission cable 31 Ground conductor 31a Insertion blade (insertion fixing part)
40 Differential signal transmission cable 41 Ground conductor 41a Insertion pin (insertion fixing part)
41b Inclined wall 50 Differential signal transmission cable 51 Ground conductor 51a Insertion blade (insertion fixing part)
51b Insertion guide wall (insertion guide)
51c Inclined wall 60 Cable for differential signal transmission 61 Conductor for ground 70 Insertion pin (insertion fixing part)

Claims (14)

A pair of signal line conductors;
An insulator provided around the signal line conductor and having a substantially elliptical cross-sectional shape ;
An outer conductor provided around the insulator;
A grounding conductor connected to the outer conductor;
A main body provided on the ground conductor;
Provided in the main body portion, and the insertion fixing portion is inserted in front Symbol body portion to the insulator for fixing to the outer conductor,
An insertion guiding portion provided in the main body for guiding the insertion fixing portion to the insertion position of the insulator;
Equipped with a,
The insertion fixing portion is located along the major axis direction of the insulator and is substantially next to the signal line conductor, and is closer to the outer conductor than an intermediate point between the signal line conductor and the outer conductor. that has plugged in, the differential signal transmission 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 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 cable for differential signal transmission according to any one of claims 1 to 3,
The differential signal transmission cable, wherein the insertion guiding portion is provided with an inclined wall for guiding the outer conductor to the insertion guiding portion. In the differential signal transmission cable according to any one of claims 1 to 4,
A differential signal transmission cable, wherein the main body portion is provided with a pair of insertion fixing portions, and the arrangement angles of the insertion fixing portions with respect to the main body portion are 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. The differential signal transmission cable according to claim 1 or 2 ,
The insertion fixing portion is a differential signal transmission cable that does not penetrate the insulator. A cable assembly comprising a pair of signal line conductors, an insulator provided around the signal line conductor and having an approximately elliptical cross-sectional shape , and an external conductor provided around the insulator is prepared. Cable assembly preparation process,
A circuit board preparation step of preparing a circuit board;
A main body part connected to the outer conductor; and an insertion fixing part for fixing the main body part to the outer conductor by being inserted into the insulator, and the insertion fixing part being connected to the insulator. A conductor preparation step for ground for preparing a conductor for ground provided with an insertion guiding portion for guiding to the insertion position;
The insertion guide portion faces the outer conductor, and the insertion fixing portion is located along the long axis direction of the insulator and is substantially beside the signal line conductor, between the signal line conductor and the outer conductor. A cable assembly step of assembling a differential signal transmission cable by inserting the ground conductor in a position closer to the outer conductor than the intermediate point of the, and fixing the ground conductor to the outer conductor;
A connection step of electrically connecting the signal line conductor and the ground conductor to the circuit board, respectively, and connecting the differential signal transmission cable to the 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 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 according to any one of claims 8 to 10,
A method of connecting a differential signal transmission cable to a circuit board, wherein the insertion guide portion is provided with an inclined wall for guiding the outer conductor to the insertion guide portion. 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 the main body portion is provided with a pair of insertion fixing portions, and the arrangement angles of the insertion fixing portions with respect to the main body portion are 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,
That form a gap between the circuit board and the insertion guiding portion, connection to the circuit board of the differential signal transmission cable.

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