Cable assembly

Abstract

To provide a cable assembly in which a coaxial cable is connected to a circuit board, which has stable characteristic impedance even during transmission of high-frequency signals, and in which crosstalk, insertion loss, and dimensional increase are suppressed.SOLUTION: In a coaxial cable connected to a circuit board, a conductive member that covers an exposed portion of a dielectric is installed on the circuit board. The conductive member covers the entire length of the exposed portion of the dielectric and is electrically connected to the outer conductor of the coaxial cable. An inner conductor of the coaxial cable is covered by the conductive member such that a gap is formed between the inner conductor and an inner conductor housing portion formed in the conductive member.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a cable assembly in which a coaxial cable or a cable constituting a differential transmission line is connected to a circuit board.

Background Art

[0002] As a cable for connecting between devices or inside a device, a cable assembly in which a plurality of coaxial cables are connected to a circuit board is widely used.

[0003] As shown in FIG. 1, in such a cable assembly, the inner conductor, dielectric, and outer conductor are gradually exposed at the tip of the coaxial cable, and the inner conductor and outer conductor are electrically connected to signal pads and ground pads provided on the circuit board using solder or the like. Such a structure is common.

[0004] By the way, for a coaxial cable, the diameter of the inner conductor, the relative permittivity of the dielectric, the inner diameter of the outer conductor layer, etc. are set so as to have a predetermined characteristic impedance. However, at the tip of the coaxial cable where the inner conductor etc. are exposed, the original structure of the coaxial cable collapses, resulting in fluctuations in the characteristic impedance.

[0005] When the frequency of the high-frequency signal transmitted by the cable assembly is relatively low (generally 10 MHz or less), the influence of the fluctuation of the characteristic impedance is small and can be ignored. However, when the frequency becomes high (generally 10 MHz or more), the influence of the fluctuation of the characteristic impedance becomes large, and there are also cases where it has an unacceptable influence on the desired signal transmission.

[0006] To address this problem, various methods for suppressing fluctuations in characteristic impedance have been proposed.

[0007] For example, in Patent Document 1, the exposed portion of the insulator of the coaxial cable is covered with a conductive member soldered to the exposed portion of the shield conductor, thereby suppressing the mismatch of the characteristic impedance.

[0008] Further, in Patent Document 2, a cable is vertically connected to a substrate having a signal layer disposed therein, and an external conductor is soldered to the ground layer of the substrate, thereby eliminating impedance mismatch at the joint of the cable to the substrate.

[0009] However, the invention described in Patent Document 1 is intended to cover the upper part of the insulator exposed portion with a conductive member, and no special measures are taken for fluctuations in characteristic impedance and deterioration of crosstalk due to the exposure of the side surface of the insulator and the conductor core wire. When the frequency of the high-frequency signal increases, an adverse effect on signal transmission is expected.

[0010] Regarding the invention described in Patent Document 2, since it is necessary to vertically connect a cable to the substrate, there is a problem that the degree of freedom in the structure of the cable assembly is small, and in particular, the dimension along the thickness direction of the substrate increases.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Patent Document 2

Disclosure of the Invention

Problems to be Solved by the Invention

[0012] An object of the present invention is to provide a cable assembly in which a coaxial cable is connected to a circuit board, and the characteristic impedance is stable even during transmission of a high-frequency signal, and crosstalk, insertion loss, and an increase in dimension are also suppressed.

Means for Solving the Problems

[0013] As a result of intensive studies on the structure of the cable assembly, the inventors have found that the above problems can be solved by providing a conductive member that covers the exposed portion of the dielectric in the coaxial cable connected to the circuit board.

Advantages of the Invention

[0014] The cable assembly of the present invention can suppress fluctuations in the characteristic impedance of the coaxial cable, and can also suppress crosstalk, insertion loss, and an increase in size. Therefore, it can be suitably used as a thin high-frequency transmission cable.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

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Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

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Figure 16

Figure 17

Figure 18

Embodiments for Carrying Out the Invention

[0016] Hereinafter, the cable assembly of the present invention will be described with reference to the drawings.

[0017] (Embodiment 1) FIG. 2 shows a cable assembly 1 according to Embodiment 1 of the present invention. The cable assembly 1 of the present invention has a structure in which a coaxial cable 10 is connected to a circuit board 40.

[0018] In Embodiment 1, six coaxial cables 10 are connected to the circuit board 40. However, in the present invention, the number of coaxial cables 10 is not particularly limited, and any number of one or more may be used according to the application of the cable assembly 1.

[0019] The coaxial cable 10 used in the present invention has an inner conductor 11, a dielectric 12 covering the outer periphery of the inner conductor 11, and an outer conductor 13 covering the outer periphery of the dielectric 12. At the tip of the coaxial cable 10, the inner conductor 11, the dielectric 12, and the outer conductor 13 are gradually exposed, and the inner conductor exposed portion 11A, the dielectric exposed portion 12A, and the outer conductor exposed portion 13A are formed and connected to the circuit board 40.

[0020] The coaxial cable 10 used in Embodiment 1 has a sheath 14 covering the outer conductor 13. However, depending on the desired form of the cable assembly 1, a coaxial cable 10 without the sheath 14 may also be used.

[0021] The lengths of the inner conductor exposed portion 11A, the dielectric exposed portion 12A, and the outer conductor exposed portion 13A are not particularly limited, and can be set to any length that causes no inconvenience when connecting to the circuit board 40. Considering the miniaturization of the cable assembly 1, it is set to about 0.5 to 1 mm.

[0022] The specific form of the coaxial cable 10 used in the present invention is not particularly limited. As long as it has the basic configuration of the coaxial cable described above, it can be appropriately selected from known coaxial cables according to the use of the cable assembly 1 and used.

[0023] The thickness of the coaxial cable 10 used in the present invention is not particularly limited, but considering the miniaturization of the cable assembly 1, a cable thinner than AWG32 can preferably be used. In Embodiment 1, a coaxial cable 10 of AWG36 was used.

[0024] The form of the inner conductor 11 of the coaxial cable 10 is not particularly limited, and it can be appropriately selected from known conductors used as the inner conductor of a coaxial cable, such as a single wire conductor or a stranded wire conductor. In Embodiment 1, a stranded wire with excellent flexibility was used.

[0025] The material used for the dielectric 12 of the coaxial cable 10 is also not particularly limited, and it can be appropriately selected from known materials used as the dielectric of a coaxial cable, such as fluororesins and polyolefins represented by polyethylene, and used. In Embodiment 1, a fluororesin with a small dielectric constant was used.

[0026] The form of the outer conductor 13 of the coaxial cable 10 is also not particularly limited, and it can be appropriately selected from known configurations used as the outer conductor of a coaxial cable, such as a braided shield, a helically wound shield, or a metal tape winding, and used. In Embodiment 1, a helically wound shield with excellent flexibility was used.

[0027] The material used for the sheath 14 of the coaxial cable 10 is not particularly limited, and it can be appropriately selected from known materials used as the sheath of coaxial cables, such as fluororesins, polyvinyl chloride, and polyolefins represented by polyethylene. In Embodiment 1, a fluororesin was used.

[0028] On the surface of the circuit board 40 used in the present invention, a pair of a signal pad 41 and a ground pad 45 corresponding to the number of coaxial cables 10 to be connected is formed.

[0029] As a typical aspect of the circuit board 40, an aspect in which the signal pad 41 is electrically connected to a connection pad 44 formed at the tip of the circuit board 40 via a signal wiring 42 formed on the surface or inner layer of the circuit board 40 can be mentioned. However, the specific aspect of the circuit board 40 can be appropriately selected according to the use of the cable assembly 1 or the like.

[0030] In the circuit board 40 in Embodiment 1, one in which the signal wiring 42 is formed in the inner layer of the substrate and is electrically connected to the signal pad 41 and the connection pad 44 via through holes 43a and 43b was used.

[0031] The connection of the coaxial cable 10 to the circuit board 40 is performed by electrically connecting the inner conductor 11 to the signal pad 41 at the inner conductor exposed portion 11A and electrically connecting the outer conductor 13 to the ground pad 45 at the outer conductor exposed portion 13A.

[0032] The electrical connection between the outer conductor 13 and the ground pad 45 is not particularly limited as long as the two are conductive, and it can be appropriately selected from connection means such as soldering, conductive adhesive, welding, and pressing and used. In Embodiment 1, soldering was used.

[0033] When a ground layer is formed on the inner layer or the back surface of the circuit board 40, it may be electrically connected to the ground pad 45 via a through hole.

[0034] The size of the circuit board 40 used in the present invention is not particularly limited and is determined according to the size and use of the device in which the cable assembly 1 is used and the number of coaxial cables 10 to be connected. Usually, those with a width of about 30 to 60 mm and a length of about 10 to 50 mm are used.

[0035] When the number of coaxial cables 10 connected to the circuit board 40 is large, it may be deformed into the mode shown in FIG. 13 in which a plurality of pairs of signal pads 41 and ground pads 45 are formed along the length direction of the circuit board 40, the mode shown in FIG. 16 in which a pair of signal pads 41 and ground pads 45 are formed on both sides of the circuit board 40 and the cables 10 are connected to both sides of the circuit board 40, or a combined mode of the two.

[0036] In the cable assembly 1 of the present invention, a conductive member 50 is installed on the circuit board 40 at a location where the coaxial cable 10 is connected to the circuit board 40.

[0037] The conductive member 50 is installed near the dielectric exposed portion 12A of the coaxial cable 10 connected to the circuit board 40. Specifically, it covers the dielectric exposed portion 12A over the entire length and is installed so that the conductive member 50 and the outer conductor 13 are electrically connected.

[0038] The dimensions of the conductive member 50 are not particularly limited and may be set to values considering the width of the circuit board 40, the arrangement of the signal pads 41, etc., and the length of the exposed portion of the inner conductor 11 at the tip of the coaxial cable 10. Usually, those with a width of about 20 to 50 mm and a length of about 2 to 5 mm are used.

[0039] When covering the dielectric exposed portion 12A with the conductive member 50, it is preferable to make as little gap as possible between the conductive member 50 and the dielectric exposed portion 12A, and cover it in a state where the conductive member 50 and the dielectric exposed portion 12A are in contact as shown in the cross-sectional view of FIG. 4.

[0040] At this time, in order to increase the area where the dielectric exposed portion 12A and the conductive member 50 are in contact, as shown in FIG. 8, a dielectric housing portion 52 is formed in the conductive member 50 along the length direction of the coaxial cable 10, and the conductive member 50 is installed so that the dielectric exposed portion 12A is housed in the dielectric housing portion 52.

[0041] As shown in FIG. 4, the dielectric housing portion 52 is formed by providing a U-shaped groove having a semi-circular portion with a diameter substantially the same as the outer diameter of the dielectric 12 on the surface of the conductive member 50 where the conductive member 50 is installed on the circuit board 40. If approximately half of the outer circumference of the dielectric 12 is in contact with the conductive member 50, the effects of the present invention can be sufficiently obtained.

[0042] By adopting such a structure in which the dielectric exposed portion 12A is covered by the conductive member 50, normally, the characteristic impedance fluctuates due to the removal of the outer conductor 13, but the conductive member 50 functions as a member corresponding to the outer conductor 13, suppressing the fluctuation and contributing to the stabilization of the characteristic impedance.

[0043] When the characteristic impedance is stabilized, stable signal transmission is possible even when the frequency of the high-frequency signal increases.

[0044] The electrical connection between the conductive member 50 and the outer conductor 13 is not particularly limited as long as the two are electrically conductive, but considering the ease of assembling the cable assembly 1, a mode in which the two are in direct contact can be preferably used.

[0045] In Embodiment 1, as shown in FIG. 8, an outer conductor housing portion 53 is formed in the conductive member 50 along the length direction of the coaxial cable 10, and the conductive member 50 is installed so that the outer conductor exposed portion 13A is housed in the outer conductor housing portion 53. At this time, as long as sufficient electrical conductivity between the outer conductor 13 and the conductive member 50 is ensured, a mode in which only a part of the outer conductor exposed portion 13A is housed in the outer conductor housing portion 53 may be used.

[0046] As shown in FIG. 3, the outer conductor housing portion 53 is formed by providing a U-shaped groove having a semi-circular portion with a diameter substantially the same as the outer diameter of the outer conductor 13 on the surface of the conductive member 50 where it is installed on the circuit board 40.

[0047] Furthermore, in Embodiment 1, the inner conductor exposed portion 11A is also covered with the conductive member 50, and the conductive member 50 functions as a member corresponding to the outer conductor 13 also in the inner conductor exposed portion 11A, contributing to suppressing fluctuations in characteristic impedance.

[0048] Similar to the dielectric exposed portion 12A, it is desirable to cover the entire length of the inner conductor exposed portion 11A with the conductive member 50, but a part of the inner conductor exposed portion 11A may not be covered by the conductive member 50 as long as the desired transmission characteristics are obtained.

[0049] In Embodiment 1, as shown in FIG. 8, an inner conductor housing portion 51 along the length direction of the coaxial cable 10 is formed in the conductive member 50, and the conductive member 50 is installed so that the inner conductor exposed portion 11A is housed in the inner conductor housing portion 51 over the entire length. At this time, as shown in FIGS. 5 and 6, a gap is provided between the inner conductor 11 and the inner conductor housing portion 51, and they are housed so as not to be electrically connected.

[0050] The inner conductor housing portion 51 is formed by providing a U-shaped groove having a dimension slightly larger than the outer diameter of the inner conductor 11 as shown in FIGS. 5 and 6 on the surface of the conductive member 50 where it is installed on the circuit board 40.

[0051] When housing the inner conductor 11 in the inner conductor housing portion 51, as shown in FIG. 6(a), it is desirable that the distance between the outer peripheral surface of the inner conductor 11 and the inner peripheral surface of the inner conductor housing portion 51 be substantially constant. By housing the inner conductor 11 in this way, the effect of suppressing fluctuations in characteristic impedance is stabilized.

[0052] Although it is ideal that the distance between the outer peripheral surface of the internal conductor 11 and the inner peripheral surface of the internal conductor housing portion 51 is substantially constant over the entire circumference of the outer peripheral surface of the internal conductor 11, it is difficult due to the connection of the internal conductor 11 to the signal pad 41. Therefore, as shown in FIG. 6(a), it is sufficient that the distance between the upper half of the outer peripheral surface of the internal conductor 11 and the inner peripheral surface of the internal conductor housing portion 51 is substantially constant.

[0053] Also, when connecting the internal conductor 11 to the signal pad 41, the internal conductor exposed portion 11A is usually bent toward the circuit board 40 as shown in FIG. 7(b). Therefore, it is difficult to maintain a state where the distance between the outer peripheral surface of the internal conductor 11 and the inner peripheral surface of the internal conductor housing portion 51 is substantially constant over the entire length of the internal conductor exposed portion 11A. At the tip of the internal conductor 11, as shown in FIG. 6(b), the distance between the outer peripheral surface of the internal conductor 11 and the top of the internal conductor housing portion 51 becomes longer.

[0054] Even in the state shown in FIG. 6(b), since the internal conductor 11 is arranged at the center in the width direction of the internal conductor housing portion 51, the effect of suppressing the variation in characteristic impedance according to the present invention can be expected and can be used as one of the aspects of the present invention. In Embodiment 1, this aspect was adopted.

[0055] As an aspect in which the internal conductor 11 is arranged at the center in the width direction of the internal conductor housing portion 51, a mode in which the distance between the outer peripheral surface of the internal conductor 11 and the top of the internal conductor housing portion 51 shown in FIG. 6(c) is shortened can also be selected.

[0056] When maintaining a state where the distance between the outer peripheral surface of the internal conductor 11 and the inner peripheral surface of the internal conductor housing portion 51 is substantially constant, as shown in FIG. 7(a), the inner peripheral surface of the internal conductor housing portion 51 is formed in a shape along the bending of the internal conductor exposed portion 11A.

[0057] In Embodiment 1, the space between the outer peripheral surface of the internal conductor 11 and the inner peripheral surface of the internal conductor housing portion 51 is an air layer. However, in order to make the effect of the conductive member 50 more stable, it is preferable to fill it with a resin material.

[0058] As the resin material to be filled between the outer peripheral surface of the inner conductor 11 and the inner peripheral surface of the inner conductor housing portion 51, materials used for the dielectric 12 of the coaxial cable 10, such as fluororesin and polyolefins typified by polyethylene, can be preferably used. However, any resin material can be used as long as the desired transmission characteristics can be obtained, and acrylic resin and the like can also be utilized.

[0059] When the effect of suppressing the variation of the characteristic impedance changes depending on the dielectric constant of the resin material to be filled, the desired effect of suppressing the variation of the characteristic impedance can be obtained by adjusting the distance between the outer peripheral surface of the inner conductor 11 and the inner peripheral surface of the inner conductor housing portion 51.

[0060] When filling the resin material between the outer peripheral surface of the inner conductor 11 and the inner peripheral surface of the inner conductor housing portion 51, in order to stabilize the effect of filling, it is advisable to also fill the resin material between the outer peripheral surface of the inner conductor 11 and the circuit board 40.

[0061] The distance between the outer peripheral surface of the inner conductor 11 and the inner peripheral surface of the inner conductor housing portion 51 is preferably about the same as the thickness of the dielectric 12 of the coaxial cable 10 when filling the resin material, and preferably a distance smaller than the thickness of the dielectric 12 when forming an air layer without filling the resin material.

[0062] In addition, when forming the inner conductor housing portion 51, as shown in Fig. 6(a), it is desirable to align the distance from the side of the signal pad 41 to the inner peripheral surface of the inner conductor housing portion 51 with the distance between the outer peripheral surface of the inner conductor 11 and the inner peripheral surface of the inner conductor housing portion 51. Since the distance between the signal pad 41 and the inner conductor housing portion 51 also affects the variation of the characteristic impedance, the effect of suppressing the variation of the characteristic impedance is stabilized by unifying the distances between each region serving as a signal transmission path and the conductive member 50.

[0063] In addition, as shown in FIGS. 6(b) and 6(c), when the distance between the outer peripheral surface of the internal conductor 11 and the top of the internal conductor housing portion 51 varies, the distance from the side of the signal pad 41 to the inner peripheral surface of the internal conductor housing portion 51 may be aligned with the distance between the outer peripheral surface of the internal conductor 11 and the side wall of the internal conductor housing portion 51.

[0064] On the other hand, considering connecting and fixing the internal conductor 11 to the signal pad 41 with solder, it is desirable to ensure a certain width of the signal pad 41 in order to stabilize the connection. Therefore, the width of the signal pad 41 may be appropriately adjusted within the range where the effect of suppressing fluctuations in characteristic impedance can be obtained.

[0065] Preferably, the width of the signal pad 41 is set to be equal to or greater than approximately the outer diameter of the internal conductor 11 and 1.5 times or less. At this time, there is a difference between the shortest distance from the side of the signal pad 41 to the inner peripheral surface of the internal conductor housing portion 51 and the distance between the outer peripheral surface of the internal conductor 11 and the inner peripheral surface of the internal conductor housing portion 51. However, if the width of the signal pad 41 is 1.5 times or less the outer diameter of the internal conductor 11, the influence on the effect of suppressing fluctuations in characteristic impedance remains within a negligible range.

[0066] Also, when a through hole 43a is connected to the signal pad 41, it is preferable to cover the through hole 43a with the conductive member 50 as well.

[0067] Due to changes in the conductive pattern width caused by the structure of the through hole, the matching state of the characteristic impedance may be affected. By covering the through hole 43a with the conductive member 50, the influence on the matching state of the characteristic impedance can be suppressed.

[0068] When covering the through hole 43a with the conductive member 50, usually, as shown in FIG. 2, an internal conductor housing portion 51 having a length sufficient to cover the through hole 43a may be formed in the conductive member 50. However, when the distance from the region where the internal conductor 11 is connected to the signal pad 41 to the portion where the through hole 43a is formed is long, a separate conductive member for covering the through hole 43a may be prepared and installed.

[0069] When installing the conductive member 50 on the circuit board 40, if the ground portion 46 is formed on the surface of the circuit board 40, the conductive member 50 may be electrically connected to the ground portion 46 as necessary. In Embodiment 1, the conductive member 50 was connected to the ground portion 46.

[0070] For the conductive member 50 of the present invention, a material having conductivity may be used after being molded into a shape according to the desired cable assembly 1. In Embodiment 1, a copper block was used with a dielectric housing portion 52 and the like formed thereon.

[0071] In addition, by press-molding a conductive plate, the conductive member 50 shown in FIG. 9 in which grooves such as the dielectric housing portion 52 are formed can also be used.

[0072] Note that the conductive member 50 does not necessarily have to be formed only of a conductive material, and a member formed of a conductive material only in the range necessary to obtain the effects of the present invention may be used.

[0073] For example, the main body portion 55 may be formed of an insulating resin, and the surface thereof may be made conductive by metal plating 56 as shown in FIG. 10. In this case, it is not always necessary to make the entire surface of the conductive member 50 conductive. A conductive member 50 in which only the inner peripheral surfaces of the internal conductor housing portion 51, the dielectric housing portion 52, and the external conductor housing portion 53 are made conductive using MID (molded circuit parts) technology or the like can also be used. FIG. 10 shows, as an example, a mode in which the inner peripheral surface of the dielectric housing portion 52 is subjected to metal plating 56.

[0074] It is desirable that the conductive member 50 covers all the coaxial cables 10. In Embodiment 1, all the coaxial cables 10 were covered with the conductive member 50. However, depending on the characteristics of the desired cable assembly 1 and the nature of the signals transmitted by the coaxial cables 10, a mode in which only some of the coaxial cables 10 are covered may be adopted.

[0075] The effects of the present invention are shown in FIG. 11. FIG. 11 is a graph of the analysis results of the characteristic impedance when the cable assembly 1 of Embodiment 1 is subjected to TDR (Time Domain Reflectometry) analysis. The rise time of the TDR analysis was set to 25 ps.

[0076] The graph of FIG. 11 shows the characteristic impedance of the cable assembly 1 of Embodiment 1 and the characteristic impedance of the cable assembly 1' of the comparative example in which the conductive member 50 is omitted from this Embodiment 1, superimposed.

[0077] According to FIG. 11, although the characteristic impedance of Embodiment 1 has some fluctuations in the time axis direction, it remains around 50 Ω and is substantially constant as a whole. From this, it can be evaluated that the effect of suppressing fluctuations in the characteristic impedance according to the present invention is obtained.

[0078] On the other hand, the characteristic impedance of the comparative example rises to 60 Ω or more around 1.33 ns, and it can be said that non-negligible fluctuations occur with respect to the reference 50 Ω.

[0079] Embodiment 1 showed an aspect in which the coaxial cable 10 in which the inner conductor 11, the dielectric 12, and the outer conductor 13 are gradually exposed at the tip is connected to the circuit board 40. However, the present invention can also be applied to a coaxial cable 10 in which the inner conductor 11 and the outer conductor 13 are gradually exposed, that is, a coaxial cable 10 in a state where the dielectric 12 is covered with the outer conductor 13 up to its tip.

[0080] When applying the present invention to the coaxial cable 10 in which the inner conductor 11 and the outer conductor 13 are gradually exposed, the conductive member 50 that omits the dielectric housing portion 52 may be used. At this time, it can also be appropriately selected and used from among the various aspects described above.

[0081] (Embodiment 2) Embodiment 2 of the present invention is shown in FIG. 12.

[0082] Embodiment 2 is an aspect in which the conductive member 50 and the external conductor 13 are brought into direct contact by bringing the tip surface of the external conductor exposed portion 13A into contact with the rear end surface of the conductive member 50.

[0083] In Embodiment 2, the dimension of the conductive member 50 in the direction along the length direction of the coaxial cable 10 can be shortened, and the miniaturization of the conductive member 50 can be promoted. Therefore, it can be said that it contributes to the miniaturization and weight reduction of the cable assembly 1.

[0084] (Embodiment 3) Embodiment 3 of the present invention is shown in FIG. 13.

[0085] The circuit board 40 used in Embodiment 3 is a cable assembly 1 in which 6 pairs × 2 rows of signal pad 41 and ground pad 45 are formed, and a total of 12 coaxial cables 10 are connected.

[0086] The coaxial cables 10 are connected to the front-end side row and the base-end side row, and the conductive members 50 are installed for the coaxial cables 10 in each row.

[0087] A cable housing portion 54 is formed on the upper surface of the conductive member 50 provided in the base-end side row, and the coaxial cables 10 connected to the front-end side row as shown in FIGS. 14 and 15 are housed.

[0088] By adopting this structure, the dimension in the thickness direction of the cable assembly 1 in the base-end side row can be suppressed, which contributes to the miniaturization of the cable assembly 1.

[0089] It is sufficient to form the cable housing portion 54 in the conductive member 50 installed in the base-end side row, but the cable housing portion 54 may be provided in the conductive member 50 installed in the front-end side row for the common use of parts.

[0090] In FIGS. 14 and 15, the coaxial cable 10 having the sheath 14 is accommodated in the cable accommodating portion 54. However, in the case of the coaxial cable 10 not having the sheath 14, the outer conductor 13 accommodated in the cable accommodating portion 54 may be electrically conductive or insulated from the conductive member 50 provided in the proximal end side row.

[0091] (Embodiment 4) Although the above embodiments have described the case where the coaxial cable 10 is connected to the circuit board 40, the present invention can also be applied to cables constituting differential transmission lines, such as twisted pair cables and two-core parallel coaxial cables, which can obtain the same shielding effect as the coaxial cable 10.

[0092] FIG. 17(a) is a diagram showing a fourth embodiment of the present invention, in which a twisted pair cable 20 shown in FIG. 17(b) is connected to a circuit board 40 to form a cable assembly 1.

[0093] The twisted pair cable 20 is formed by twisting conductors 21 covered with insulators 22, and has an effect of suppressing radiation of electromagnetic induction noise and a shielding effect of external electromagnetic induction noise due to the twisted structure, contributing to stabilization of transmission characteristics.

[0094] When connecting the twisted pair cable 20 to the circuit board 40, the twist is released near the signal pad 41, so the effect due to the above-described twisted structure is lost, which may affect the transmission characteristics.

[0095] Therefore, by installing the conductive member 50 at a portion where the conductor 21 of the twisted pair cable 20 is electrically connected to the signal pad 41, the influence on the transmission characteristics can be suppressed.

[0096] Since the insulated wire constituting the twisted pair cable 20 is composed of the conductor 21 and the insulator 22, the conductive member 50 is installed so as to cover the tip portions of the conductor 21 and the insulator 22 at the connection portion with the circuit board 40.

[0097] Following the internal conductor housing portion 51 and the dielectric housing portion 52 in Embodiment 1, a conductor housing portion 510 and an insulator housing portion 520 may be provided on the surface of the circuit board 40 where the conductive member 50 is installed. In Embodiment 4, the conductor housing portion 510 is in a non-contact state with respect to the conductor 21, and the insulator housing portion 520 is in a contact state with respect to the insulator 22.

[0098] When the circuit board 40 corresponds to the mode shown in Embodiment 3, that is, when a plurality of rows of signal pads 41 are formed, it is preferable that a cable housing portion 54 for housing the twisted pair cable 20 connected to the group of signal pads 41 on the tip side is provided on the conductive member 50 on the base end side.

[0099] (Embodiment 5) FIG. 18(a) is a diagram showing a fifth embodiment of the present invention, in which a two-core parallel coaxial cable 30 shown in FIG. 18(b) is connected to a circuit board 40 to form a cable assembly 1.

[0100] The two-core parallel coaxial cable 30 generally has a structure in which two electric wires each composed of a conductor 31 and an insulating layer 32 are arranged in parallel, and a shield layer 33 and an outer skin 34 are provided on the outer periphery thereof as shown in FIG. 18(b).

[0101] When connecting the two-core parallel coaxial cable 30 to the circuit board 40, the shield layer 33 is removed near the signal pad 41, so that the shielding effect of the shield layer 33 is lost, which may affect the transmission characteristics.

[0102] Therefore, by installing the conductive member 50 at the portion where the conductor 31 of the two-core parallel coaxial cable 30 is electrically connected to the signal pad 41, the influence on the transmission characteristics can be suppressed.

[0103] When using the two-core parallel coaxial cable 30, the conductive member 50 can adopt a mode following that when using the twisted pair cable 20.

[0104] The cables connected to the circuit board 40 may be a coaxial cable 10, a twisted pair cable 20, and a two-core parallel coaxial cable 30 mixed together. In this case, conductive members 50 with specifications changed according to the types of cables may be prepared individually, or a housing portion corresponding to each cable may be formed in one conductive member 50.

[0105] In addition, as a cable constituting a differential transmission line, one using two coaxial cables 10 to form a differential transmission line can also be used.

[0106] (Summary of the Embodiment) Regarding the technical idea grasped from the embodiments described above, it will be described by referring to the reference numerals and the like in the embodiments. However, each reference numeral and the like in the following description are not limited to the members and the like specifically shown in the embodiments for the components in the claims.

[0107] [1] A cable assembly (1) in which a coaxial cable (10) having an inner conductor (11), a dielectric (12) covering the outer periphery of the inner conductor (11), and an outer conductor (13) covering the outer periphery of the dielectric (12) is connected to a circuit board (40), At the tip of the coaxial cable (10), at least the inner conductor (11) and the outer conductor (13) are exposed stepwise, so that an inner conductor exposed portion (11A) and an outer conductor exposed portion (13A) are respectively formed, A signal pad (41) and a ground pad (45) are formed on the circuit board (40), The inner conductor (11) is electrically connected to the signal pad (41) at the inner conductor exposed portion (11A), The outer conductor (13) is electrically connected to the ground pad (45) at the outer conductor exposed portion (13A), It has a conductive member (50) installed on the surface of the circuit board (40), The conductive member (50) is provided with an internal conductor accommodating portion (51) that covers at least a part of the internal conductor exposed portion (11A), and is installed on the surface of the circuit board (40) such that a gap is formed between the outer peripheral surface of the internal conductor exposed portion (11A) and the inner peripheral surface of the internal conductor accommodating portion (51), and is electrically connected to the external conductor (13). The cable assembly (1) is characterized by this.

[0108] [2] The cable assembly (1) according to [1] above, wherein the internal conductor exposed portion (11A) is arranged at the center in the width direction of the internal conductor accommodating portion (51).

[0109] [3] The cable assembly (1) according to [1] or [2] above, wherein the gap between the outer peripheral surface of the internal conductor exposed portion (11A) and the inner peripheral surface of the internal conductor accommodating portion (51) is a substantially constant distance.

[0110] [4] At the tip of the coaxial cable (10), the internal conductor (11), the dielectric (12), and the external conductor (13) are exposed step by step, so that a dielectric exposed portion (12A) is formed between the internal conductor exposed portion (11A) and the external conductor exposed portion (13A), and The conductive member (50) is provided with a dielectric accommodating portion (52) that covers the dielectric exposed portion (12A), and the conductive member (50) is installed on the surface of the circuit board (40) such that the outer peripheral surface of the dielectric exposed portion (12A) and the inner peripheral surface of the dielectric accommodating portion (52) are in contact. The cable assembly (1) according to any one of [1] to [3] above is characterized by this.

[0111] [5] The conductive member (50) is provided with an external conductor accommodating portion (53) that covers the external conductor exposed portion (13A), and the cable assembly (1) according to any one of [1] to [4] above is characterized by the outer peripheral surface of the external conductor exposed portion (13A) and the inner peripheral surface of the external conductor accommodating portion (53) being in contact.

[0112] [6] When the side on which the inner conductor exposed portion (11A) of the coaxial cable (10) is formed is defined as the tip side and the opposite side is defined as the base end side, a pair of the signal pad (41) and the ground pad (45) to which the coaxial cable (10) is connected are formed in a plurality of rows on the circuit board (40) from the tip side toward the base end side, and a cable housing portion (54) capable of housing the coaxial cable (10) connected to the row on the tip side is formed on at least one surface of the conductive member (50) installed in rows other than the foremost tip side. The cable assembly (1) according to any one of [1] to [5] above, characterized in that.

[0113] [7] A cable assembly (1) in which a differential transmission line is configured using two insulated wires each having a conductor (21, 31) and an insulation coating (22, 32) covering the outer periphery of the conductor (21, 31) is connected to a circuit board (40), At the tip of the cable, a conductor exposed portion where the conductors (21, 31) are exposed is formed, A signal pad (41) is formed on the circuit board (40), The conductors (21, 31) are electrically connected to the signal pad (41) at the conductor exposed portion, It has a conductive member (50) installed on the surface of the circuit board (40), The conductive member (40) is installed so as to cover the insulation coating (22, 32) near the conductor exposed portion and at least a part of the conductor exposed portion. The cable assembly (1) characterized by that.

[0114] [8] A conductor housing portion (510) covering the conductor exposed portion is formed in the conductive member (50), and a gap is formed between the outer peripheral surface of the conductor exposed portion and the inner peripheral surface of the conductor housing portion (510). The cable assembly (1) according to [7] above, characterized in that.

[0115] [9] The conductor exposed portion is arranged at the center in the width direction of the conductor housing portion (510). The cable assembly (1) according to [8] above, characterized in that.

[0116]

[10] The cable assembly (1) according to [8] or [9] above, characterized in that the gap between the outer peripheral surface of the conductor exposed portion and the inner peripheral surface of the conductor housing portion (510) is a substantially constant distance.

[0117]

[11] The cable assembly (1) according to any one of [7] to

[10] above, characterized in that an insulating coating housing portion (520) that covers the insulating coatings (22, 32) near the conductor exposed portion is formed in the conductive member (50), and the outer peripheral surface of the insulating coatings (22, 32) is in contact with the inner peripheral surface of the insulating coating housing portion (520).

[0118]

[12] The cable assembly (1) according to any one of [7] to

[11] above, characterized in that the cable in which the differential transmission line is configured is a twisted pair cable (20) or a two-core parallel coaxial cable (30).

[0119] Also, a configuration in which the configurations described in [1] to

[12] above are appropriately selected and combined also belongs to the technical scope of the present disclosure.

[0120] Although the embodiments of the present invention have been described above, the embodiments described above do not limit the invention according to the claims. Also, not all combinations of the features described in the embodiments are essential means for solving the problems of the invention. Further, the present invention can be appropriately modified and implemented without departing from its gist.

Industrial Applicability

[0121] The cable assembly according to this invention can suppress fluctuations in characteristic impedance at the circuit board connection portion of the cable, so that the transmission characteristics can be kept in a good state, and thus it can be suitably used as a wiring member for various devices that handle high-frequency signals.

Explanation of Signs

[0122] 1 Cable assembly 10 Coaxial cable 11 Inner Conductor 11A Inner Conductor Exposed Portion 12 Dielectric 12A Dielectric Exposed Portion 13 Outer Conductor 13A Outer Conductor Exposed Portion 14 Sheath 20 Twisted Pair Cable 21 Conductor 22 Insulation Coating 30 Two-Core Parallel Coaxial Cable 31 Conductor 32 Insulation Coating 33 Shield Layer 34 Outer Sheath 40 Circuit Board 41 Signal Pad 42 Signal Wiring 43a Through-Hole 43b Through-Hole 44 Connection Pad 45 Ground Pad 46 Ground Portion 50 Conductive Member 51 Inner Conductor Accommodation Portion 510 Conductor Accommodation Portion 52 Dielectric Accommodation Portion 520 Insulation Coating Accommodation Portion 53 Outer Conductor Accommodation Portion 530 Shield Layer Accommodation Portion 54 Cable Accommodation Portion 55 Resin Main Body Portion 56 Metal Plated Portion 60 Conductive Member

Claims

1. A cable assembly in which a coaxial cable having an inner conductor, a dielectric covering the outer periphery of the inner conductor, and an outer conductor covering the outer periphery of the dielectric is connected to a circuit board, at the tip of the coaxial cable, at least the inner conductor and the outer conductor are exposed stepwise, so that an inner conductor exposed portion and an outer conductor exposed portion are respectively formed, a signal pad and a ground pad are formed on the circuit board, the inner conductor is electrically connected to the signal pad at the inner conductor exposed portion, the outer conductor is electrically connected to the ground pad at the outer conductor exposed portion, having a conductive member installed on the surface of the circuit board, the conductive member is installed on the surface of the circuit board such that an inner conductor accommodating portion covering at least a part of the inner conductor exposed portion is formed, and a gap is formed between the outer peripheral surface of the inner conductor exposed portion and the inner peripheral surface of the inner conductor accommodating portion, and is electrically connected to the outer conductor. A cable assembly characterized by being.

2. The cable assembly according to claim 1, wherein the inner conductor exposed portion is disposed at the center in the width direction of the inner conductor accommodating portion.

3. The cable assembly according to claim 2, wherein the gap between the outer peripheral surface of the inner conductor exposed portion and the inner peripheral surface of the inner conductor accommodating portion is a substantially constant distance.

4. At the tip of the coaxial cable, the inner conductor, the dielectric, and the outer conductor are exposed stepwise, so that a dielectric exposed portion is formed between the inner conductor exposed portion and the outer conductor exposed portion, and the conductive member is formed with a dielectric accommodating portion covering the dielectric exposed portion, and the conductive member is installed on the surface of the circuit board such that the outer peripheral surface of the dielectric exposed portion and the inner peripheral surface of the dielectric accommodating portion are in contact. The cable assembly according to any one of claims 1 to 3.

5. The cable assembly according to any one of claims 1 to 3, wherein the conductive member is formed with an outer conductor accommodating portion covering the outer conductor exposed portion, and the outer peripheral surface of the outer conductor exposed portion and the inner peripheral surface of the outer conductor accommodating portion are in contact.

6. The conductive member is formed with an outer conductor accommodating portion that covers the outer conductor exposed portion, and the outer peripheral surface of the outer conductor exposed portion is in contact with the inner peripheral surface of the outer conductor accommodating portion. The cable assembly according to claim 4, characterized in that.

7. When the side where the inner conductor exposed portion of the coaxial cable is formed is the tip side and the opposite side is the base end side, a pair of the signal pad and the ground pad to which the coaxial cable is connected are formed in a plurality of rows on the circuit board from the tip side to the base end side, and at least one surface of the conductive member installed in a row other than the foremost row is formed with a cable accommodating portion capable of accommodating the coaxial cable connected to the row on the tip side. The cable assembly according to any one of claims 1 to 3, characterized in that.

8. When the side where the inner conductor exposed portion of the coaxial cable is formed is the tip side and the opposite side is the base end side, a pair of the signal pad and the ground pad to which the coaxial cable is connected are formed in a plurality of rows on the circuit board from the tip side to the base end side, and at least one surface of the conductive member installed in a row other than the foremost row is formed with a cable accommodating portion capable of accommodating the coaxial cable connected to the row on the tip side. The cable assembly according to claim 4, characterized in that.

9. When the side where the inner conductor exposed portion of the coaxial cable is formed is the tip side and the opposite side is the base end side, a pair of the signal pad and the ground pad to which the coaxial cable is connected are formed in a plurality of rows on the circuit board from the tip side to the base end side, and at least one surface of the conductive member installed in a row other than the foremost row is formed with a cable accommodating portion capable of accommodating the coaxial cable connected to the row on the tip side. The cable assembly according to claim 5, characterized in that.

10. When the side where the exposed portion of the inner conductor of the coaxial cable is formed is defined as the tip side and the opposite side is defined as the base end side, a pair of the signal pad and the ground pad to which the coaxial cable is connected is formed in a plurality of rows on the circuit board from the tip side toward the base end side, and a cable accommodating portion capable of accommodating the coaxial cable connected to the row on the tip side is formed on at least one surface of the conductive members installed in rows other than the row on the foremost tip side. The cable assembly according to claim 6, characterized in that.

11. A cable assembly in which a cable configured with a differential transmission line using two insulated electric wires having a conductor and an insulating coating covering the outer periphery of the conductor is connected to a circuit board, At the tip of the cable, an exposed conductor portion where the conductor is exposed is formed, A signal pad is formed on the circuit board, The conductor is electrically connected to the signal pad at the exposed conductor portion, Having a conductive member installed on the surface of the circuit board, The conductive member is installed so as to cover at least a part of the insulating coating near the exposed conductor portion and the exposed conductor portion. The cable assembly characterized by the above.

12. A conductor accommodating portion for covering the exposed conductor portion is formed in the conductive member, and a gap is formed between the outer peripheral surface of the exposed conductor portion and the inner peripheral surface of the conductor accommodating portion. The cable assembly according to claim 11, characterized in that.

13. The exposed conductor portion is arranged at the center in the width direction of the conductor accommodating portion. The cable assembly according to claim 12, characterized in that.

14. The gap between the outer peripheral surface of the exposed conductor portion and the inner peripheral surface of the conductor accommodating portion is a substantially constant distance. The cable assembly according to claim 13, characterized in that.

15. An insulating coating accommodating portion for covering the insulating coating near the exposed conductor portion is formed in the conductive member, and the outer peripheral surface of the insulating coating and the inner peripheral surface of the insulating coating accommodating portion are in contact with each other. The cable assembly according to any one of claims 11 to 14, characterized in that.

16. The cable configured with the differential transmission line is a twisted pair cable or a two-core parallel coaxial cable. The cable assembly according to any one of claims 11 to 14, characterized in that.

17. The cable assembly according to claim 15, characterized in that the cable in which the differential transmission line is formed is a twisted pair cable or a two-core parallel coaxial cable.

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