CN110415876B

CN110415876B - Shielding flat cable

Info

Publication number: CN110415876B
Application number: CN201910343471.5A
Authority: CN
Inventors: 小岛千明; 松田龙男
Original assignee: Sumitomo Electric Industries Ltd
Current assignee: Sumitomo Electric Industries Ltd
Priority date: 2018-04-27
Filing date: 2019-04-26
Publication date: 2022-06-21
Anticipated expiration: 2039-04-26
Also published as: CN110415876A; TW201946071A; JP7040265B2; TWI805701B; JP2019192573A

Abstract

The invention provides a shielded flat cable which can reliably connect a shielding layer to a terminal on the side of a substrate together with a plurality of flat conductors through a simple structure. A shielded flat cable (1) is provided with: a plurality of flat conductors (11) arranged in parallel; a pair of insulating layers (21, 22) which are bonded to both surfaces of the parallel surfaces of the plurality of flat conductors (11); and a shield layer (41) that covers at least one of the insulating layers (21, 22), wherein a cable terminal portion that exposes the flat conductor (11) is formed at an end portion of one of the insulating layers (22) in the longitudinal direction. A ground conductor (31) is provided on the outer peripheral side of the cable end portion side of one insulating layer (22), a contact piece (32) integrally provided on the ground conductor (31) is electrically connected to a predetermined flat conductor (11), and a shield layer (41) is electrically connected to the flat conductor (11) via the ground conductor (31).

Description

Shielding flat cable

Technical Field

The invention relates to a shielded flat cable.

Background

Flexible Flat Cables (FFCs) are used in a wide variety of fields such as AV equipment including CD and DVD players, OA equipment including copiers and printers, and internal wiring of other electronic and information equipment for the purpose of space saving and easy connection. In addition, if the frequency of use of the device becomes high, the influence of noise becomes large, and therefore a shielded flat cable is used.

The flat cable is shielded by providing a shield layer on the outside of the FFC, for example. In addition, the shielded flat cable has a terminal portion connected to the connector at an end portion. In the terminal portion, a structure for ground connection of the shield layer to the ground pad of the connector is required. For example, patent document 1 discloses a shielded flat cable having a ground conductor electrically connected to a shield layer.

Patent document 1: japanese patent application laid-open No. 2010-153191

A connector having a plurality of terminals that contact exposed surfaces of a plurality of flat conductors arranged in parallel of the FFC is generally provided on a substrate side to which the FFC is connected. In the shielded flat cable disclosed in patent document 1, the height positions in the thickness direction of the exposed surfaces of the terminal portions of the plurality of parallel flat conductors and the exposed surface of the ground conductor are different from each other. Therefore, in order to ground the ground conductor, it is necessary to bring the ground conductor into contact with the metal cover portion of the connector, or to separately provide a ground terminal at a height position in the thickness direction different from that of the terminal for the flat conductor. Further, in some connectors, in order to increase the degree of freedom of the structure, the metal cover portion and the ground terminal may not be provided.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a shielded flat cable capable of reliably connecting a shield layer to a terminal on a substrate side together with a plurality of flat conductors by a simple structure.

A shielded flat cable according to an aspect of the present invention includes: a plurality of flat conductors arranged in parallel; a pair of insulating layers attached to both surfaces of the parallel surfaces of the plurality of flat conductors; and a shield layer covering at least one of the insulating layers, wherein a cable terminal portion exposing the flat conductor is formed at an end portion of one of the insulating layers in a longitudinal direction, and a ground conductor electrically connected to a predetermined flat conductor and the shield layer is provided on an outer peripheral side of the one of the insulating layers on a side of the cable terminal portion.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, since the shield layer can be electrically connected to the predetermined flat conductor via the ground conductor, the shield layer can be reliably electrically connected to the terminal of the connector on the substrate side together with the plurality of flat conductors.

Drawings

Fig. 1 is a schematic view of a shielded flat cable according to embodiment 1 of the present invention.

Fig. 2 is a diagram for explaining an example of a manufacturing process of the shielded flat cable according to embodiment 1 of the present invention.

Fig. 3 is a diagram for explaining an example of a manufacturing process of the shielded flat cable according to embodiment 1 of the present invention.

Fig. 4 is a diagram for explaining an example of a manufacturing process of the shielded flat cable according to embodiment 1 of the present invention.

Fig. 5 is a diagram for explaining an example of a manufacturing process of the shielded flat cable according to embodiment 1 of the present invention.

Fig. 6 is a schematic view of a shielded flat cable according to embodiment 2 of the present invention.

Description of the reference symbols

1 … shielded flat cable, 11 … flat conductor, 21, 22 … insulating layer, 31' …

Ground conductor, 32 … contact pad, 41, 42 … shield.

Detailed Description

(description of embodiments of the invention)

First, embodiments of the present invention will be described by way of example.

(1) A shielded flat cable according to an aspect of the present invention includes: a plurality of flat conductors arranged in parallel; a pair of insulating layers attached to both surfaces of the parallel surfaces of the plurality of flat conductors; and a shield layer covering at least one of the insulating layers, wherein a cable terminal portion exposing the flat conductor is formed at an end portion of one of the insulating layers in a longitudinal direction, and a ground conductor electrically connected to a predetermined flat conductor and the shield layer is provided on an outer peripheral side of the one of the insulating layers on a side of the cable terminal portion.

With this configuration, the shield layer can be electrically connected to the predetermined flat conductor via the ground conductor, and therefore the shield layer can be reliably electrically connected to the terminal of the connector on the substrate side together with the plurality of flat conductors.

(2) Preferably, the ground conductor integrally has a contact piece electrically connected to the predetermined flat conductor. With this configuration, the ground conductor and the predetermined flat conductor can be electrically connected with each other reliably.

(3) The ground conductor may be located between one of the insulating layers and the shield layer. With this configuration, the height difference in the thickness direction between the flat conductor and the ground conductor can be reduced, and the flat conductor and the ground conductor can be electrically connected easily.

(4) The ground conductor may be located on an outer peripheral side of the shield layer. Thus, the shield layer is positioned on the outer peripheral side of the insulating layer, and therefore the distance between the shield layer and the flat conductor can be made constant.

(5) The ground conductor may be provided around the pair of insulating layers, and the shield layer may be provided so as to be in contact with the ground conductor on outer circumferential sides of the pair of insulating layers. With this configuration, the shield layer can be provided so as to sandwich the parallel surfaces of the flat conductors with the insulating layer interposed therebetween, and therefore, a favorable shield effect can be obtained.

(details of the embodiment of the present invention)

Hereinafter, a preferred embodiment of the shielded flat cable according to the present invention will be described with reference to the drawings. In the following description, the same reference numerals are used in different drawings to designate the same components, and the description thereof may be omitted. The present invention is not limited to the examples of the embodiments, and includes all modifications within the scope of the features described in the claims and the equivalent scope. In addition, as long as a plurality of embodiments can be combined, the present invention includes a mode in which arbitrary embodiments are combined.

(embodiment 1)

Fig. 1 is a schematic view of a shielded flat cable according to embodiment 1 of the present invention, in which fig. 1(a) is a perspective view and fig. 1(B) is a cross-sectional view taken at 1B-1B of fig. 1 (a).

The shielded flat cable 1 according to the present embodiment includes a plurality of flat conductors (flat conductors) 11,

insulating layers

21 and 22, a ground conductor 31, and a shield layer 41. For example, a flat cable 1 in which a plurality of flat conductors 11 having a flat cross section (flat shape) and extending in the X-axis direction are arranged in parallel in the Y-axis direction and both surfaces in the direction (Z-direction) orthogonal to the arrangement plane (XY-plane) of the flat conductors 11 are sandwiched between

insulating layers

21 and 22 and covered is used. At least one end of the shielded flat cable 1 is provided with a cable terminal portion (portion of width a) formed by removing the insulating layer 22 located on the upper side in the Z-axis direction in the drawing, and the flat conductor 11 is exposed. The cable terminal portion serves as a connection terminal portion for connecting the shielded flat cable 1 to a connector. The cable terminal portion may be formed without the insulating layer 22 at the end portion from the beginning, and the flat conductor 11 serving as the connection terminal portion may be exposed.

The flat conductors 11 are made of metal such as copper foil or tin-plated soft copper foil, and are arranged in an appropriate size such as a thickness of 10 to 100 μm, a width of 0.2 to 0.8mm, and a pitch P of 0.4 to 2.0mm, depending on the current value of signal transmission. The arrangement of the flat conductors 11 is held between the

insulating layers

21 and 22. The flat conductor 11 is used for signal transmission, but a predetermined flat conductor 11 is grounded when connected to a connector terminal on the substrate side. For example, when the signal line is S and the ground line is G, the flat conductors 11 are arranged such that 2 signal lines S and 1 ground line G are repeated in the parallel direction (Y-axis direction) as G-S-S-G. Here, 2 adjacent signal lines are used for differential transmission.

As shown in fig. 1(a) and 1(B), a ground conductor 31 is provided on the outer peripheral side of the cable end portion side of the upper insulating layer 22. The ground conductor 31 is provided with a plurality of contact pieces 32 extending integrally from the ground conductor 31, and each contact piece 32 is electrically connected to an exposed surface of the flat conductor 11 serving as the ground line G. Further, a shield layer 41 is provided on the outer peripheral side of the ground conductor 31 and the insulating layer 22. The arrangement of the ground conductor 31 and the shield layer 41 may be reversed, and the ground conductor 31 may be arranged on the outer peripheral side of the shield layer 41. In this case, the lower surface (the insulating layer 22 side) of the ground conductor 31 is electrically connected to the shield layer 41. In the present invention, the flat conductor 11 is defined as the inner side, and the outer peripheral side means either or both of the outer direction of the upper and lower surfaces of the parallel surfaces of the flat conductor 11 and the outer direction of the left and right end surfaces.

The insulating layers 21 and 22 have an adhesive layer (not shown) on their inner surfaces (bonding surfaces). The insulating layers 21 and 22 themselves are formed of a general resin film having excellent flexibility, and for example, a resin film having general versatility such as a polyester resin, a polyphenylene sulfide resin, or a polyimide resin can be used. The thickness of the resin film is 9 to 100 μm. Examples of the polyester resin include resin materials such as polyethylene terephthalate resin, polyethylene naphthalate resin, and polybutylene naphthalate resin. Among these resin films, polyethylene terephthalate resins are preferably used from the viewpoint of electrical characteristics, mechanical characteristics, cost, and the like.

As the adhesive layer of the insulating

layers

21 and 22, an adhesive layer made of a resin material is used, and examples thereof include an adhesive in which a flame retardant is added to a polyester resin or a polyolefin resin. The adhesive layer is formed to have an appropriate thickness in the range of 10 to 150 μm. The insulating layers 21 and 22 are bonded and integrated by opposing the adhesive layers with the flat conductor 11 interposed therebetween and bonding them together by heating with a heating roller. Further, a reinforcing plate may be provided on the opposite side of the exposed surface of the flat conductor 11 of the cable terminal portion. The insulating layers 21 and 22 may be formed of a single layer resin such as polyethylene, polypropylene, polyimide, polyethylene terephthalate, polyester, or polyphenylene sulfide, for example, without using an adhesive layer. In this case, the thickness of the resin is, for example, about 300 μm.

The ground conductor 31 has a 2-layer structure having a conductive adhesive layer on a metal foil such as an aluminum foil or a copper foil. In the ground conductor 31, a contact piece 32 is provided integrally with the flat conductor 11 at a position corresponding to the ground line G, and is electrically connected to the flat conductor 11 serving as the ground line G through a conductive adhesive layer provided on the contact piece 32. The electrical connection between the contact piece 32 and the ground line G may be made by solder, ultrasonic welding, laser welding, or the like, in addition to the conductive adhesive material.

The shield layer 41 has an overall thickness of about 30 μm, and when the shield layer 41 is provided on the outer peripheral side of the ground conductor 31, for example, a 2-layer structure of a metal layer and a conductive adhesive layer is used, and the conductive adhesive layer is attached to the ground conductor 31 and the insulating layer 22 with the conductive adhesive layer being on the inside. As a method of bonding, as shown in fig. 1(a) and 1(B), at least the entire outer circumference side of the flat conductor 11 may be covered on one surface of the exposed surface side of the flat conductor 11, but may be provided over the entire circumference of the flat cable. When the ground conductor 31 is provided on the outer peripheral side of the shield layer 41, a 2-layer structure including a metal layer and an adhesive layer is used. For example, an insulating layer such as PET may be provided on the surface of an aluminum foil, the aluminum foil at the connection portion with the ground conductor 31 at the end may be exposed, and the exposed portion may be connected to the ground conductor 31. The shield layer 41 may have a 3-layer structure in which a resin layer is interposed between a metal foil and an adhesive layer in order to adjust the distance from the flat conductor 11.

Next, an example of a method for manufacturing the shielded flat cable according to the present embodiment will be described. Fig. 2 to 5 are views for explaining an example of a manufacturing process of the shielded flat cable according to embodiment 1 of the present invention. In fig. 2 to 5, (a) is a view seen from above, and (B) shows a sectional view, for example, (B) of fig. 2 is a sectional view at 2B-2B in (a) of fig. 2.

As shown in fig. 2 (a) and 2 (B), a plurality of flat conductors 11 are arranged in parallel, the upper and lower sides of the parallel surfaces are sandwiched between insulating

layers

21 and 22 having adhesive layers provided inside, and the insulating

layers

21 and 22 are bonded to both surfaces of the flat conductors 11 by heating with a heating roller, thereby producing an integrated long flat cable.

Next, as shown in fig. 3 (B), which is a cross-sectional view of fig. 3 a and 3B-3B thereof, one insulating layer, here, the upper insulating layer 22 of the portion to be the terminal of the flat cable is removed by, for example, laser processing with the width a of the terminal to be the cable terminal portion, so that the plurality of flat conductors 11 are exposed. In the case of manufacturing a plurality of shielded flat cables, from the viewpoint of improving manufacturing efficiency, the terminal portion of the rear end of the 1 st shielded flat cable and the terminal portion of the front end of the 2 nd shielded flat cable following the shielded flat cable are simultaneously formed and finally divided along a dividing line C-C indicated by a two-dot chain line shown in fig. 3 (a). Therefore, in fig. 3 (a), the exposed surfaces of the plurality of flat conductors 11 are formed to have a width 2 times as large as the width a of the terminal at the cable terminal portion.

As a method of exposing the flat conductor 11 in a predetermined shape from one insulating layer 22, in addition to the method of providing an opening in the insulating layer 22 by laser processing as described above, a method of providing an opening in a predetermined position of the insulating layer 22 in advance may be used. In the latter case, the flat conductor 11 may be sandwiched between the insulating layer 21 and the insulating layer 22 provided with the opening to produce a flat cable, and then the connection portion of the opening may be removed.

Next, as shown in fig. 4 (B), which is a cross-sectional view taken along 4B-4B of fig. 4 (a), the ground conductor 31 is attached to the outer peripheral side of the upper insulating layer 22 on the cable end side. In this case, the contact piece 32 of the ground conductor 31 is positioned so as to be positioned on the exposed surface of the flat conductor 11 serving as the ground line G, and the contact piece 32 is attached to the exposed surface of the flat conductor 11. At this time, since there is a difference in level between the exposed surface of the flat conductor 11 and the upper surface of the insulating layer 22, the contact piece 32 is fixed to the exposed surface of the flat conductor 11 in a bent state by the conductive adhesive layer. The ground conductor 31 having the contact piece 32 can be obtained by pressing a metal foil provided with a conductive adhesive layer.

Next, as shown in fig. 5 (a) and a cross-sectional view taken along 5B-5B of fig. 5, that is, fig. 5(B), the conductive adhesive layer of the shield layer 41 is attached to the upper surfaces of the ground conductor 31 and the insulating layer 22 so as to face the ground conductor 31 side. In the present embodiment, the shield layer 41 is provided only on one side of the insulating layer 22 side of the shield flat cable 1, but may be wound around the entire circumference including the upper and lower surfaces. Then, the flexible flat cables are cut along the dividing line C-C in order to separate the front and rear shielded flat cables. The flexible flat cable may be cut before the ground conductor 31 is attached.

Although the description has been given above of the case where the shield layer 41 is provided on the outer peripheral side of the ground conductor 31, the ground conductor 31 may be provided on the outer peripheral side of the shield layer 41. In this case, after the step shown in fig. 3 (a), the shield layer 41 is attached to the upper side of the insulating layer 22, and the ground conductor 31 is electrically connected to the upper side of the shield layer 41.

(embodiment 2)

Fig. 6 is a schematic view of a shielded flat cable according to embodiment 2 of the present invention, in which fig. 6 (a) is a perspective view and fig. 6 (B) is a cross-sectional view taken at 6B-6B of fig. 6 (a).

In embodiment 1, the shield layer 41 is provided on one side of the shielded flat cable 1, but as shown in this embodiment, the shield layer may be provided on both sides. In this case, as shown in fig. 6 (a), the ground conductor 31' is located not only on the insulating layer 22 side but also on the insulating layer 21 side on the opposite side, and is provided so as to surround the outer peripheries of the insulating

layers

21 and 22. The shield layers 41 and 42 are provided on the outer peripheral sides of the insulating

layers

22 and 21, respectively. This can improve the noise immunity. Instead of providing the shielding layers 41 and 42 on the insulating

layers

21 and 22, respectively, the shielding layers may be provided so as to surround the entire circumference of the flat cable. The other structures are the same as those of embodiment 1, and therefore, the description thereof is omitted.

In addition, as a method of exposing the flat conductor at the cable end portion, an insulating layer may be provided in advance in a portion other than a portion where the flat conductor is to be exposed, in addition to a method of removing the insulating layer.

Claims

1. A shielded flat cable having: a plurality of ground lines; a plurality of paired signal lines; a pair of insulating layers attached to both surfaces of the parallel surfaces of the ground line and the signal line; and a shield layer covering at least one of the insulating layers, wherein a cable terminal portion exposing the ground line and the signal line is formed at an end portion of one of the insulating layers in a longitudinal direction,

in the case of the shielded flat cable as such,

the paired signal lines are disposed between each of the plurality of ground lines,

a 2-layer structure ground conductor having a metal foil and a conductive adhesive layer is provided on the outer peripheral side of the cable end portion side of the one insulating layer,

the ground conductor is electrically connected to the plurality of ground lines and the shield layer,

the grounding conductor integrally has a plurality of contact pieces electrically connected to the plurality of grounding wires via the conductive adhesive layer,

the paired signal lines are used for differential transmission.

2. The shielded flat cable of claim 1,

the signal line and the ground line are arranged such that one end of the signal line is the signal line and the other end of the signal line is the ground line.

3. The shielded flat cable according to claim 1 or 2,

the ground conductor is located between one of the insulating layers and the shielding layer.

4. The shielded flat cable according to claim 1 or 2,

the ground conductor is located on an outer peripheral side of the shield layer.

5. The shielded flat cable according to claim 1 or 2,

the ground conductor is provided around the pair of insulating layers, and the shield layer is provided so as to be in contact with the ground conductor on outer peripheral sides of the pair of insulating layers.

6. The shielded flat cable of claim 3,

7. The shielded flat cable of claim 4,