JP2024034851A - Flat cable connection structure and connection method - Google Patents

Abstract

The present invention provides a flat cable connection structure and connection method that can improve communication performance on a high-speed transmission line. SOLUTION: A connection structure 1 for a flat cable 10 in which conductors 11a, 11b of a flat cable 10 in which a plurality of conductors 11 arranged at intervals are covered with an insulating material are connected to a bus bar 21, wherein the conductors 11a, 11b has a connection part 13 that is a part connected to the bus bar 21, and the connection part 13 is arranged at the ends of the conductors 11a and 11b. [Selection diagram] Figure 2

Description

The present invention relates to a connection structure and connection method for flat cables capable of transmitting communication signals.

As a conventional flat cable, one in which a plurality of conductors arranged at intervals in the width direction and for transmitting power and electric signals are coated with an insulating material is known (see, for example, Patent Document 1).

Conventional flat cables are connected to other devices via connectors with bus bars. For this reason, in conventional flat cables, the conductor is exposed by removing the insulation at a spaced apart portion from the end, and the exposed conductor is connected to the bus bar.

In a flat cable, some of the plurality of conductors may be used as a high-speed transmission line (for example, a differential transmission line) for transmitting communication signals. In a high-speed transmission line, if there is a portion where the characteristic impedance changes, the waveform of the communication signal may be disturbed and communication performance may deteriorate. For this reason, the flat cable is adjusted so that the characteristic impedance is a predetermined value over the entire length of the conductor.

Japanese Patent Application Publication No. 2001-6774

However, in conventional flat cables, the part of the conductor that is spaced apart from the end is connected to the bus bar, so communication signals may be reflected between the part of the conductor where the bus bar is connected and the end. , attenuation may occur, which may reduce communication performance.

An object of the present invention is to provide a flat cable connection structure and connection method that can improve communication performance on a high-speed transmission line.

A flat cable connection structure according to the present invention is a flat cable connection structure in which a plurality of conductors arranged at intervals are coated with an insulating material, and the conductors of the flat cable are connected to a connection target, wherein the conductors are , has a connecting part that is a part connected to the connection target, and the connecting part is arranged at an end of the conductor.

Further, in the flat cable connection structure according to the present invention, the average value of the size in the thickness direction of the connection part is 0.7 times or more the size in the thickness direction of the other part of the conductor. It is within the range of .85 times or less.

Further, in the flat cable connection structure according to the present invention, the size of the connection portion in the thickness direction gradually decreases toward the end of the conductor.

Further, a flat cable connecting method according to the present invention is a flat cable connecting method in which the conductor of a flat cable in which a plurality of conductors arranged at intervals are coated with an insulating material is connected to a connection target, the flat cable connecting method comprising: a conductor exposing step of exposing the conductor by removing the insulating material at a portion spaced from the end of the flat cable; and connecting the conductor exposed in the conductor exposing step to the connection target. and a conductor cutting step of cutting an end portion of the conductor beyond the connection portion.

Further, in the flat cable connection method according to the present invention, the connection part forming step forms the connection part in a state where a pressing force is applied to the conductor placed on the connection target, and the thickness of the connection part is The average value of the size in the direction is within the range of 0.7 times or more and 0.85 times or less of the size of the other portion of the conductor in the thickness direction.

Further, in the flat cable connecting method according to the present invention, the connecting portion forming step forms the connecting portion while applying a pressing force to the conductor placed on the connection target, and the thickness of the connecting portion is The directional magnitude gradually decreases toward the ends of the conductor.

Further, in the flat cable connection method according to the present invention, the conductor cutting step cuts the conductor using a pressing force applied when forming the connection portion in the connection portion forming step.

According to the present invention, since the end of the conductor is connected to the connection target, it is possible to suppress reflection and attenuation of communication signals transmitted between the conductor and the connection target,
It becomes possible to improve communication performance on high-speed transmission lines.

FIG. 2 is a plan view of main parts showing a connection state between a flat cable and a bus bar according to the first embodiment of the present invention. FIG. 2 is a side view of a main part showing a connection state between a flat cable and a bus bar according to a first embodiment of the present invention. FIG. 1 is a plan view of main parts of a flat cable according to a first embodiment of the present invention. FIG. 3 is a schematic diagram illustrating a method of forming a connecting portion according to a first embodiment of the present invention. FIG. 1 is a perspective view of an ultrasonic horn according to a first embodiment of the present invention. FIG. 3 is a schematic diagram illustrating a method of connecting a flat cable to a bus bar according to a first embodiment of the present invention. It is a schematic diagram explaining other connection methods of the flat cable to the bus bar concerning a 2nd embodiment of the present invention.

<First embodiment>
1 to 6 show a first embodiment of the present invention. FIG. 1 is a plan view of the main part showing the connection state between the flat cable and the bus bar, FIG. 2 is a side view of the main part showing the connection state between the flat cable and the bus bar, and FIG. 3 is a plan view of the main part of the flat cable. FIG. 4 is a schematic diagram illustrating a method of forming a connecting portion, FIG. 5 is a perspective view of an ultrasonic horn, and FIG. 6 is a schematic diagram illustrating a method of connecting a flat cable to a bus bar.

The flat cable 10 provided with the connection structure 1 of the present invention is used, for example, as a component of a so-called steering roll connector provided at a connecting portion between a steering column on the vehicle body side and a steering shaft on the steering wheel side. be. The flat cable 10 constitutes a part of a conductive circuit for transmitting electric power between a device provided on the vehicle body side and a device provided on the steering wheel side, and also transmits electrical signals. It forms part of the communication circuit for The communication circuit performs high-speed communication of, for example, 100 Mbps or more.

As shown in FIGS. 1 and 3, the flat cable 10 is formed into an integral band shape by covering a plurality of conductors 11 arranged at intervals in the width direction with an insulating material 12. The size of the flat cable 10 in the thickness direction is, for example, 125 μm. Further, the plurality of conductors 11 are arranged at intervals of, for example, 0.4 mm or more and 1 mm or less.

Each of the plurality of conductors 11 is made of, for example, copper or a copper alloy, and has a thickness of, for example, 35 μm. Further, among the plurality of conductors 11 arranged in the width direction of the flat cable 10, a pair of communication conductors 11a in the width direction constituting a communication circuit is arranged on the central part side in the width direction. A pair of grounding conductors 11b are arranged on both widthwise outer sides of the grounding conductor 11b. The pair of communication conductors 11a and the pair of ground conductors 11b are each formed to have a widthwise size of 100 μm.

The flat cable 10 is connected to a conductive circuit and a communication circuit via a connector 20. As shown in FIG. 1, the flat cable 10 has a plurality of conductors 11 each connected to a bus bar 21 as a connection target that constitutes a connector 20. As shown in FIG. The bus bar 21 is, for example, a conductive member such as brass.

In this embodiment, the connection structure 1 is applied to connect each of the pair of communication conductors 11a and the pair of ground conductors 11b to the bus bar 21. Hereinafter, the pair of communication conductors 11a and the pair of ground conductors 11b to which the connection structure 1 is applied will be simply referred to as conductors 11a and 11b.

As shown in FIGS. 1 and 2, the connection structure 1 includes a connection portion 13 that is a portion of the conductors 11a, 11b of the flat cable 10 that is connected to the bus bar 21. As shown in FIG. 2, the connecting portions 13 are arranged at the ends of the conductors 11a and 11b.

The connecting portion 13 is formed by joining the conductors 11a, 11b to the bus bar 21 by ultrasonic metal joining, and the average value of the size T1 in the thickness direction is equal to that of the other portions of the conductors 11a, 11b in the thickness direction. It is formed to have a size within a range of 0.7 times or more and 0.85 times or less with respect to the size T2.

Here, the target value of the tensile strength, which is the maximum strength against the tensile force applied to the conductors 11a, 11b including the connection portion 13 and the bus bar 21, is 1.3 to 1.6N. Further, the target value of the peeling stress, which is the maximum strength against the force for peeling off one of the conductors 11a, 11b and the bus bar 21 including the connecting portion 13, from the other is 1.1 to 1.2N. If the average value of the size T1 in the thickness direction is less than 0.7 times the size T2 in the thickness direction of other parts of the conductors 11a and 11b, it is applied during ultrasonic metal bonding. The damage to the conductors 11a and 11b caused by the pressing force is large, and the tensile strength and peel strength do not reach the target values. In addition, if the average value of the size T1 in the thickness direction is 0.85 times or more the size T2 in the thickness direction of other parts of the conductors 11a and 11b, joining by ultrasonic metal bonding Due to insufficient force, the peel strength will not reach the target value.

In the connection structure 1 for the flat cable 10 configured as described above, in ultrasonic metal bonding, as shown in FIG. used.

The ultrasonic horn 30 includes a rectangular contact surface 31 that contacts the conductors 11a and 11b, and a convex portion 32 that extends along one side of the contact surface 31 and projects from the contact surface 31. It has . The abutment surface 31 is formed to be slightly larger in the width direction than the width directions of the conductors 11a and 11b. Further, the convex portion 32 is disposed on the end portion side of the conductors 11a, 11b on the contact surface 31, with the contact surface 31 in contact with the conductors 11a, 11b.

The abutting surface 31 of the ultrasonic horn 30 may be a smooth surface, as shown in FIG. 5(a), or may be a smooth surface, as shown in FIG. It may have a protrusion that extends across the plane, or it may have a plurality of protrusions that intersect with each other, as shown in FIG. 5(c).

In the ultrasonic bonding, first, the conductors 11a and 11b are placed on the upper surface of the bus bar 21, as shown in FIG. 6(a). Next, as shown in FIG. 6(b), the contact surface 31 of the ultrasonic horn 30 is brought into contact with the conductors 11a, 11b, and a pressing force is applied to the conductors 11a, 11b by the ultrasonic horn 30. , applying ultrasonic vibration to the conductors 11a and 11b to form the connection portion 13. When forming the connecting portion 13, the convex portion 32 protruding from the contact surface 31 of the ultrasonic horn 30 contacts and cuts across the width of the conductors 11a and 11b, as shown in FIG. 6(c). As such, the ends of the conductors 11a and 11b are cut from the connection portion 13.

Hereinafter, a method for forming the connection structure 1 of the flat cable 10 described above will be described.

First, as a conductor exposure step, the insulating material 12 at a portion spaced apart from the end of the flat cable 10 is removed across the width to partially expose the conductors 11a and 11b, as shown in FIG.

Next, as a connection part forming step, the connection part 13 is formed by connecting the exposed portions of the flat cable 10 with the conductors 11a and 11b to the bus bar 21 by ultrasonic bonding.

Finally, as a conductor cutting step, the end portions of the conductors 11a and 11b are cut from the connection portions 13.

As described above, according to the flat cable connection structure of the present embodiment, the flat cable connects the conductors 11a and 11b of the flat cable 10, which has a plurality of conductors 11 arranged at intervals covered with an insulating material, to the bus bar 21. In the connection structure 1 of No. 10, the conductors 11a and 11b have a connection part 13 that is a part connected to the bus bar 21, and the connection part 13 is arranged at the end of the conductors 11a and 11b.

Further, according to the flat cable connection method of the present embodiment, the flat cable 10 connects the conductors 11a and 11b of the flat cable 10, which has a plurality of conductors 11 arranged at intervals covered with an insulating material, to the bus bar 21. The connection method includes a conductor exposing step of exposing the conductors 11a, 11b by removing the insulating material 12 at a spaced apart portion from the end of the flat cable 10, and a conductor exposing step of exposing the conductors 11a, 11b exposed in the conductor exposing step. The process includes a connection part forming step of forming the connection part 13 by connecting to the bus bar 21, and a conductor cutting process of cutting the end portion of the flat cable 10 from the connection part 13.

As a result, the ends of the conductors 11a, 11b are connected to the bus bar 21, so it is possible to suppress reflection and attenuation of communication signals transmitted between the conductors 11a, 11b and the bus bar 21. It becomes possible to improve communication performance.

In addition, the average value of the size T1 in the thickness direction of the connecting portion 13 is within a range of 0.7 times or more and 0.85 times or less with respect to the size T2 in the thickness direction of other parts of the conductors 11a and 11b. It is preferable that it be within.

In addition, in the connection part forming step, the connection part 13 is formed in a state where a pressing force is applied to the conductors 11a and 11b placed on the bus bar 21, and the average value of the size T1 in the thickness direction of the connection part 13 is It is preferable that the thickness be within a range of 0.7 times or more and 0.85 times or less with respect to the size T2 in the thickness direction of the other portions 11a and 11b.

Thereby, it becomes possible to reliably connect the conductors 11a, 11b and the bus bar 21 without breaking the conductors 11a, 11b.

Further, in the conductor cutting step, it is preferable that the conductors 11a and 11b are cut by a pressing force applied when forming the connecting portion 13 in the connecting portion forming step.

This makes it possible to simultaneously form the connection portion 13 and cut the conductors 11a and 11b, thereby making it possible to improve productivity.

<Second embodiment>
FIG. 7 shows a second embodiment of the present invention, and is a schematic diagram illustrating another method of connecting a flat cable to a bus bar. Note that the same components as those in the embodiment described above are denoted by the same reference numerals.

The connection structure 1 of the flat cable 10 of this embodiment has a connection part 13a whose size in the thickness direction gradually decreases toward the ends of the conductors 11a and 11b.

As shown in FIG. 7, the connecting portion 13a is formed by an ultrasonic horn 30a having an abutment surface 31a that is an inclined surface that gradually projects downward in the direction in which the conductors 11a and 11b extend. In the ultrasonic horn 30a of this embodiment, the convex portion 32 is not formed.

In the ultrasonic bonding of this embodiment, first, the conductors 11a and 11b are placed on the upper surface of the bus bar 21, as shown in FIG. 7(a). Next, as shown in FIG. 7(b), the contact surface 31a of the ultrasonic horn 30a is brought into contact with the conductors 11a, 11b, and a pressing force is applied to the conductors 11a, 11b by the ultrasonic horn 30a. , applying ultrasonic vibration to the conductors 11a and 11b to form the connection portion 13. When forming the connecting portion 13, an incision is made by the end of the contact surface 31a of the ultrasonic horn 30 in contact across the width direction of the conductors 11a and 11b, as shown in FIG. 7(c). The ends of the conductors 11a and 11b are cut away from the connection portion 13.

As described above, according to the flat cable connection structure and connection method of the present embodiment, the ends of the conductors 11a and 11b are connected to the bus bar 21, as in the above embodiment, so that the conductors 11a and 11b It becomes possible to suppress reflection and attenuation of communication signals transmitted between the bus bar 21 and the bus bar 21, and it becomes possible to improve communication performance.

Further, it is preferable that the size of the connecting portion 13a in the thickness direction gradually decreases toward the end of the conductor.

In addition, in the connection part forming step, the connection part 13 is formed in a state where a pressing force is applied to the conductors 11a, 11b placed on the bus bar 21, and the size of the connection part 13 in the thickness direction is the same as that of the conductors 11a, 11b. It is preferable that the size gradually decreases toward the end.

Thereby, it becomes possible to reliably join the conductors 11a, 11b and the bus bar 21 without breaking the conductors 11a, 11b.

In the above embodiment, the ultrasonic horns 30, 30a are used to cut the ends of the conductors 11a, 11b from the connecting parts 13, 13a, but the present invention is not limited to this. Only cuts may be made in the conductors 11a and 11b, and the end portions of the conductors 11a and 11b may be separated from the connecting portions 13 and 13a in a separate process.

Further, in the above embodiment, the connection structure of the present invention is applied to a flat cable as a component of a steering roll connector, but if it is a flat cable having a conductor that constitutes a part of a communication circuit, It is not limited to connectors.

1 Connection structure 10 Flat cable 11 Conductor 11a Communication conductor 11b Ground conductor 12 Insulating material 13 Connection portion 21 Bus bar 30, 30a Ultrasonic horn 31, 31a Contact surface 32 Convex portion

Claims (7)

A flat cable connection structure in which a plurality of conductors arranged at intervals are coated with an insulating material and the conductors of the flat cable are connected to a connection target,
The conductor has a connection part that is a part connected to the connection target,
The connection part is arranged at the end of the conductor. Flat cable connection structure. The average value of the size in the thickness direction of the connecting portion is within a range of 0.7 times or more and 0.85 times or less of the size in the thickness direction of other parts of the conductor. Flat cable connection structure described in . The flat cable connection structure according to claim 1, wherein the connection portion has a size in the thickness direction that gradually decreases toward an end of the conductor. A method for connecting a flat cable in which a plurality of conductors arranged at intervals are coated with an insulating material and the conductors of the flat cable are connected to a connection target, the method comprising:
a conductor exposing step of exposing the conductor by removing the insulating material at a distance from the end of the flat cable;
a connecting portion forming step of forming a connecting portion by connecting the conductor exposed in the conductor exposing step to the connection target;
A method for connecting a flat cable, comprising: a conductor cutting step of cutting an end portion of the conductor relative to the connection portion. In the connection part forming step, the connection part is formed while applying a pressing force to the conductor placed on the connection target, and the average value of the thickness direction of the connection part is set to a value other than that of the conductor. 5. The flat cable connection method according to claim 4, wherein the size in the thickness direction of the portion is within a range of 0.7 times or more and 0.85 times or less. In the connection portion forming step, the connection portion is formed while applying a pressing force to the conductor placed on the connection target, and the size of the connection portion in the thickness direction is directed toward the end of the conductor. 5. The flat cable connection method according to claim 4, wherein the flat cable gradually becomes smaller. 7. The flat cable connection method according to claim 5, wherein in the conductor cutting step, the conductor is cut by a pressing force applied when forming the connection portion in the connection portion forming step.

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