The present application claims priority from Japanese Patent Application No. 2016-112139 filed on Jun. 3, 2016, the content of which is hereby incorporated by reference into this application.
The present invention relates to a communication cable having a cable and a connector formed on an end portion of the cable.
The cable configuring the communication cable has a signal line, an insulator which covers the signal line, a shield member which covers the insulator, and an insulating member which covers the shield member. Moreover, a multi-core cable is included in the cable configuring the communication cable. The multi-core cable described here means a cable obtained by collectively bundling a plurality of cables into one cable, each of which has the signal line, the insulator covering the signal line, the shield member covering the insulator and the insulating member covering the shield member. In the following explanation, individual cables included in the multi-core cable are referred to as “core cables” in some cases. Furthermore, when core cables included in the multi-core cable are used for transmitting operation signals, the core cable has a pair of signal lines, an insulator covering these signal lines, a shield member covering the insulator and an insulating member covering the shield member.
A connector which is formed on the end portion of the cable including the multi-core cable is connectable to a communication device such as a server, a network switch or others. For example, the connector has a case that is insertable/removable to/from a slot (cage) formed on the communication device and a substrate housed in this case, and the end portion of the cable including the multi-core cable is connected to the substrate inside the case. More specifically, a connector pad is formed on one side of the substrate, and a signal pad and a ground pad are formed on the other side of the substrate.
Here, when the cable configuring the communication cable is a multi-core cable, the multi-core cable and the connector are connected with each other as follows to form one communication cable. On the end portion of the multi-core cable, a cable sheath or others is removed so that each core cable is exposed. On the end portion of each of the exposed core cables, an insulating member is removed so that the shield member and the signal line are exposed, and therefore, the shield member is solder-joined to the ground pad on the substrate so that the signal line is solder-joined to the signal pad on the substrate. Moreover, each base of the exposed core cables is integrally molded by resin.
On the other hand, the end portion of the substrate on which the connector pad is formed protrudes from the tip of the case so as to form a plug connector of a card edge type. When the case is inserted into the slot of the communication device, the end portion (plug connector) of the substrate on which the connector pad is formed is inserted into a receptacle connector formed inside the slot. Then, the connector pad formed on the substrate and a connection terminal formed on the receptacle connector are made in contact with each other so that the both of them are electrically connected to each other.
Patent Document 1: Japanese Patent Application Laid-open Publication No. 2013-251223
A plurality of slots are formed on the communication device, and these slots are arranged adjacent to each other. In recent years, the number of slots has tended to increase in order to achieve a high function and a high speed of the communication device. On the other hand, it is also required to downsize the communication device. Therefore, in order to add the slots while meeting the requirement for the downsizing of the communication device, a plurality of slots are arranged with a higher density.
That is, the connector of the communication cable is configured to be connected to each of the plurality of slots that are arranged with a high density. As a result, a large number of communication cables are drawn from a front panel and a rear panel of the communication device on which the slot is formed, and therefore, a degree of freedom in handling the communication cables in the vicinity of the communication device is lowered. Under such circumstances, a bending force and a tensile force are applied to the cables configuring the communication cable often.
Here, when the cable configuring the communication cable is a multi-core cable, the base of each of core cables is molded by resin inside the connector (case). However, this molding resin is used for molding the bases of the plurality of core cables onto each other, but not used for molding the connection portions between the core cables and the substrate. That is, the joint portion between the shield member and the substrate and the joint portion between the signal line and the substrate are not molded.
For this reason, when a bending force and a tensile force exceeding an assumed range are applied to the multi-core cable extending from the case, there is a risk of application of an excessive force to the connection portion between each core cable and the substrate, which results in damaging the connection portion. For example, there are risks of peeling off of the ground pad to which the shield member is solder-joined from the substrate and peeling off of the signal pad to which the signal line is solder-joined from the substrate. Moreover, there are also risks of peeling off of the solder-joint portion between the shield member and the ground pad and peeling off of the solder-joint portion between the signal line and the signal pad. There is a risk of occurrence of such damages of these connection portions even when the cable configuring the communication cable is not the multi-core cable.
An object of the present invention is to achieve a communication cable in which the connection portion between the cable and the substrate is difficult to be damaged even when the force exceeding the assumed range is applied to the cable.
In an aspect of the present invention, the communication cable includes a cable and a connector formed on an end portion of the cable, the cable including a signal line, an insulator covering the signal line, a shield member covering the insulator, and an insulating member covering the shield member. Moreover, the communication cable includes a case which is inserted/removed to/from a slot formed on the communication device to which the communication cable is connected, a substrate housed in the case and to which the cable is connected, a first joint portion at which the signal line and the substrate are solder-joined to each other, a second joint portion at which the shield member and the substrate are solder-joined to each other, and a resin portion molding a connection portion between the cable and the substrate. The connection portion excluding the first joint portion and the second joint portion is molded by the resin portion.
In another aspect of the present invention, the connection portion including the second joint portion is molded by the resin portion.
According to the present invention, it is possible to achieve a communication cable in which a connection portion between a cable and a substrate is hardly damaged even when a force exceeding an assumed range is applied to the cable.
Hereinafter, one example of an embodiment of a communication cable of the present invention will be described in detail with reference to the drawings. In the following explanation, note that the same or substantially the same components are denoted with the same reference character in each reference drawing.
A communication cable 1 shown in
As shown in
The shield tape 22 is a laminate body formed of a resin film and a metal film, and is longitudinally wrapped around the insulator 21 so that the resin film is placed inside. The wrapping tape 23 is a tape for preventing loosening of the shield tape 22, and is laterally wrapped (helically wrapped) around the shield tape 22. Note that the shield tape 22 of the present embodiment is a laminate body formed of a PET film and a copper film. However, a material for each film configuring the shield tape 22 is not limited to such a specific material. Moreover, the number of the laminating films configuring the shield tape 22 is not limited to such a specific number of laminating films, either.
With reference to
As shown in
The connector 3 (case 30) has a shape and a dimension that are insertable/removable to/from the slot (cage) formed in the communication device. When the connector 3 is inserted into the cage, a locking piece formed on the cage is engaged with the connector 3. Meanwhile, when the pull tab 35 is pulled rearward to slide the latch 33 in the same direction, the engagement of the locking piece with the connector 3 is released. Specifically, the above-described locking piece is formed on each of both sidewalls of the cage, which face with each other. When the connector 3 is inserted into the cage, each locking piece is fitted to an engaging portion formed on each of both side surfaces of the connector 3. As a result, the locking pieces are engaged with the connector 3, so that the connector 3 is not pulled out of the cage. On the other hand, when the pull tab 35 is pulled to slide the latches 33 rearward, the locking pieces engaged with the engaging portions are pushed outward from the engaging portions by the tips of the latches 33. As a result, the engagement of the locking pieces with the connector 3 is released, so that the connector 3 can be pulled out of the cage.
Next, mainly with reference to
As shown in
Further, on the front surface of the substrate 40, a placing portion 46 is formed between the short side 40b and the connection pad group 44. In other words, a region between the short side 40b and the connection pad group 44 is the placing portion 46. This placing portion 46 is a region where an end portion of the core cable 10 connected to the substrate 40 is placed, and a width (W) of the placing portion 46 is 5 mm. Here, the width (W) of the placing portion 46 is a dimension of the placing portion 46 along a longitudinal direction of the substrate 40.
Although not shown in the drawings, the same four connection pad groups 44 are also formed on the rear surface of the substrate 40. That is, eight connection pad groups 44 in total are formed on the substrate 40. And, the same connector pads and placing portions as the connector pads 41 and the placing portions 46 shown in
As shown in
As shown in
As shown in
Note that a ring-shaped shield connection member 2a shown in
As shown in
The signal line 20 and the shield tape 22 that are exposed at the end portion of each of the branch wires 10a are connected to the connection pad group 44 corresponding to each of the branch wires 10a. More specifically, the signal lines 20a and 20b of one branch wire 10a are solder-joined to the signal pads 43 and 43 belonging to the corresponding connection pad group 44, respectively, and the shield tape 22 of the branch wire 10a is solder-joined to the ground pad 42 belonging to the same connection pad group 44 as the connection pad group 44 to which the signal pads 43 belong, the signal pads 43 being solder-joined with the signal lines 20a and 20b of the corresponding branch wire 10a.
Therefore, the substrate 40 has eight joint portions at each of which the corresponding core cable 10 (branch wire 10a) and the connection pad group 44 are solder-joined to each other. Specifically, the front surface of the substrate has four joint portions, and the rear surface of the substrate has four joint portions. Moreover, as shown in
As shown in
On the other hand, as shown in
As described above, in the present embodiment, the plurality of core cables 10 included in the multi-core cable 2 are solder-joined to the substrate 40. At the same time, portions of the ends of the respective core cables 10, the portions being not solder-joined to the substrate 40, are collectively molded by the resin portion 50. Further, portions of the ends of the respective core cables 10, the portions being molded by the resin portion 50 (the portions being not solder-joined), are fixed to the placing portion 46 of the substrate 40 by the adhesive. Therefore, even when a bending force and a tensile force are applied to the multi-core cable 2 extending from the connector 3 (case 30), the connection portion between each core cable 10 and the substrate 40, that is, the first joint portion and second joint portion, are difficult to be damaged. For example, the solder joint between the signal line 20 and signal pad 43 at the first joint portion is difficult to be broken, and the signal pad 43 is difficult to be peeled off from the front surface of the substrate. Note that the adhesive for fixing the end portion of the core cable 10 to the placing portion 46 of the substrate 40 also plays a role of temporarily fixing the end portion of the core cable 10 to the substrate 40 in the process of forming the resin portion 50.
Meanwhile, the first joint portion and the second joint portion of the connection portion between the core cable 10 and the substrate 40 are not molded by the resin portion 50. Therefore, impedances of the first joint portion and the second joint portion are not lowered by a dielectric constant of the resin portion 50. Therefore, even when a high-speed signal of several tens of Gbit/sec or higher is transmitted, reflection of the signal due to impedance mismatching does not occur.
Of course, the present invention has an embodiment in which the second joint portion is molded by the resin portion 50. In other words, the present invention has an embodiment in which the shield tape 22 is molded by the resin portion 50. This embodiment is inferior to the embodiment in which the first joint portion and the second joint portion are not molded in the impedance matching, but superior thereto in the connection strength. Further, even when the shield tape 22 is molded by the resin portion 50, the influence on the signal transmission is small.
The present invention is not limited to the above-described embodiments, and can be variously modified within a scope of the invention. For example, the resin portion 50 in the above-described embodiments is made of polyamide. However, the resin material for forming the resin portion 50 is not particularly limited to this material. In place of polyamide, the resin portion 50 may be made of, for example, polypropylene or ethylene-vinyl acetate copolymer resin.
Furthermore, from the viewpoint of suppressing the damage on the connection portion due to an external force, it is preferable to form the resin portion 50 by a resin material having a tensile shear adhesive strength of 4.8 Mpa or more.
Further, the adhesive layer 47 according to the above-described embodiments is made of a cyanoacrylate-based adhesive. Of course, the adhesive forming the adhesive layer 47 is not limited to a specific adhesive. Of course, when the adhesive layer 47 is made by an adhesive applied to be overlapped onto the solder resist layer formed on the front surface of the placing portion 46, it is required to select an adhesive which is not prevented from being cured by the solder resist layer.
The width (W) of the placing portion 46 shown in
The communication cable of the present invention includes a communication cable having a connector formed on an end portion of one cable in which a signal line is covered with an insulator, in which the insulator is covered with a shield member, and in which the shield member is covered with an insulating member. Moreover, the cable configuring the communication cable of the present invention includes a multi-core cable obtained by collectively bundling a plurality of core cables into one cable, each of which includes one signal line. That is, the multi-core cable including a plurality of core cables that are not used for transmission of differential signals is also included in the cable configuring the communication cable of the present invention.
Number | Date | Country | Kind |
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2016-112139 | Jun 2016 | JP | national |