TWI805701B - Shielded flat cable - Google Patents

Abstract

The present invention provides a shielded flat cable with a simple structure in which a shielding layer and a plurality of flat conductors are reliably connected to a terminal on the board side. The shielded flat cable 1 of the present invention has a plurality of flat conductors 11 arranged in parallel, a pair of insulating layers 21, 22 attached to the two sides of the parallel surfaces of the plurality of flat conductors 11, and at least one of the covering insulating layers 21, 22. One is the shielding layer 41 , and a cable end portion where the flat conductor 11 is exposed is formed at an end portion of the insulating layer 22 in the longitudinal direction. A grounding conductor 31 is provided on the outer peripheral side of the cable end portion of an insulating layer 22, and the contact piece 32 integrally provided on the grounding conductor 31 is electrically connected to a predetermined flat conductor 11, and the shielding layer 41 is electrically connected through the grounding conductor 31. Connected to the flat conductor 11.

Description

Shielded flat cable

The invention relates to a shielded flat cable.

Flexible flat cable (FFC) is used for AV equipment such as CD or DVD players, OA equipment such as photocopiers or printers, and internal wiring of other electronic and information equipment for the purpose of saving space and easy connection. field. In addition, if the frequency of use of the equipment becomes higher, the influence of noise will increase, so a shielded flat cable with shielding is used.

The shielding of the shielded flat cable is performed, for example, by providing a shielding layer outside the FFC. Also, the shielded flat cable has a terminal portion connected to a connector at an end portion. At the end portion, a structure for grounding the shield layer to the ground pad provided on the connector is required. For example, Patent Document 1 discloses a shielded flat cable having a ground conductor electrically connected to a shield layer. [Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2010-153191

[Problem to be Solved by the Invention]

A connector is usually provided on the side of the substrate to which the FFC is connected, and the connector has a plurality of terminals that contact the exposed surfaces of the plurality of flat conductors arranged in parallel with the FFC. In the shielded flat cable disclosed in Patent Document 1, the exposed surface of the terminal portion of the plurality of flat conductors arranged in parallel is different from the exposed surface of the ground conductor in the height direction in the thickness direction. Therefore, in order to ground the grounding conductor, it is necessary to make the grounding conductor contact the metal shell of the connector, or provide a separate grounding terminal at a different height in the thickness direction from the terminal for the flat conductor. Also, depending on the connector, in order to increase the degree of freedom of the structure, there may be cases where a metal case or a terminal for grounding is not provided.

The present invention has been made in view of these circumstances, and an object of the present invention is to provide a shielded flat cable that can reliably connect a shield layer and a plurality of flat conductors to a terminal on the board side with a simple structure. [Technical means to solve the problem]

A shielded flat cable according to an aspect of the present invention has a plurality of flat conductors arranged in parallel, a pair of insulating layers attached to the two sides of the parallel surfaces of the plurality of flat conductors, and at least one of the insulating layers covering The shielding layer, and the end of the length direction of one of the above-mentioned insulating layers is formed with the cable end portion exposed by the above-mentioned flat conductor, wherein a grounding conductor is provided on the outer peripheral side of the cable end portion of one of the above-mentioned insulating layers, The ground conductor is electrically connected to the predetermined flat conductor and the shielding layer. [Effect of Invention]

According to the present invention, since the shielding layer can be electrically connected to a predetermined flat conductor through the ground conductor, the shielding layer and the plurality of flat conductors can be reliably and electrically connected to the terminal of the connector on the substrate side.

(Description of Embodiments of the Invention of the Claim) First, an embodiment of the present invention will be cited and described. (1) A shielded flat cable according to an aspect of the present invention has a plurality of flat conductors arranged in parallel, a pair of insulating layers bonded to the two sides of the parallel surfaces of the plurality of flat conductors, and a layer covering the insulating layer. At least one of the shielding layers, and the end of the length direction of one of the above-mentioned insulating layers is formed with the exposed cable end of the flat conductor, wherein the outer peripheral side of the above-mentioned cable end of one of the above-mentioned insulating layers is provided with A ground conductor, the ground conductor is electrically connected to the predetermined above-mentioned flat conductor and above-mentioned shielding layer.

With this configuration, the shielding layer can be electrically connected to a predetermined flat conductor through the ground conductor, so that the shielding layer can be reliably and electrically connected to the terminal of the connector on the board 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 can be reliably and electrically connected to a predetermined flat conductor.

(3) The ground conductor may also be located between one of the insulating layers and the shielding layer. With this configuration, the step difference in the thickness direction between the flat conductor and the ground conductor can be reduced, so that the electrical connection between the flat conductor and the ground conductor can be easily performed.

(4) The ground conductor may be located on the outer peripheral side of the shield layer. Thereby, the shielding layer is located on the outer peripheral side of the insulating layer, so the distance between the shielding layer and the flat conductor can be fixed.

(5) The ground conductor may be provided around a pair of the insulating layers, and the shielding layer may be provided in contact with the ground conductor on the outer peripheral side of each of the pair of insulating layers. With this configuration, since the shielding layer can be provided so as to sandwich the parallel surfaces of the flat conductors through the insulating layer, a good shielding effect can be obtained.

(Details of the embodiment of the present invention) Hereinafter, preferred embodiments of the shielded flat cable of the present invention will be described with reference to the drawings. In the following description, in different drawings, the configurations attached with the same symbols are also assumed to be the same, and the description thereof may be omitted. In addition, the present invention is not limited to the illustrations in these embodiments, and includes all changes within the scope of the matters described in the claims and within the range of equality. Moreover, as long as a plurality of embodiments can be combined, the present invention includes combinations of arbitrary embodiments.

(first embodiment) 1 is a schematic diagram showing a shielded flat cable according to a first embodiment of the present invention, FIG. 1(A) is a perspective view, and FIG. 1(B) is a cross-sectional view at 1B-1B of FIG. 1(A).

The shielded flat cable 1 of this embodiment is composed of a plurality of flat conductors 11 , insulating layers 21 and 22 , a ground conductor 31 , and a shielding layer 41 . The shielded flat cable 1 uses, for example, a plurality of flat conductors 11 that have a flat cross section and extend in the X-axis direction, and a plurality of them are arranged in parallel in the Y-axis direction. (XY plane) A flat cable coated on both sides in the orthogonal direction (Z direction). On at least one end of the shielded flat cable 1, the insulating layer 22 located on the upper side in the Z-axis direction in the figure is removed to form a cable end portion (portion of width A), so that the flat conductor 11 is exposed. This cable end portion serves as a connection terminal portion when connecting the shielded flat cable 1 to the connector. In addition, the end portion of the cable may be formed without the insulating layer 22 at the end portion from the beginning, exposing the flat conductor 11 to be the connection terminal portion.

The flat conductor 11 is made of metal such as copper foil, tinned soft copper foil, etc. It also depends on the current value of signal transmission. For example, the thickness is 10 μm-100 μm, the width is about 0.2-0.8 mm, and the pitch P is 0.4-2.0 mm. The appropriate size arrangement. The arrangement state of the flat conductors 11 is held by being sandwiched between the insulating layers 21 and 22 . Although the flat conductor 11 is used for signal transmission, a predetermined flat conductor 11 is grounded when connected to a connector terminal on the board side. For example, regarding the flat conductor 11, when the signal line is S and the ground line is G, in the parallel direction (Y-axis direction), two signal lines S and 1 The ground wires G are arranged in a repeated manner. Here, two adjacent signal lines are used for differential transmission.

As shown in FIG. 1(A) and FIG. 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 integrally extending from the ground conductor 31 , and each contact piece 32 is electrically connected to the exposed surface of the flat conductor 11 which becomes the ground line G. In addition, a shield layer 41 is provided on the outer peripheral side of the ground conductor 31 and the insulating layer 22 . In addition, the arrangement of the ground conductor 31 and the shielding layer 41 can be reversed, and the grounding conductor 31 can also be arranged on the outer peripheral side of the shielding layer 41 . In this case, the lower surface (side of the insulating layer 22 ) of the ground conductor 31 is electrically connected to the shielding layer 41 . In addition, in the present invention, the so-called outer peripheral side refers to any one or both of the outer direction of the upper and lower sides of the parallel surface of the flat conductor 11 and the outer direction of the left and right end surfaces with the flat conductor 11 as the inner side.

The insulating layers 21 and 22 have an adhesive layer (not shown) on their inner surfaces (joint surfaces). The insulating layers 21 and 22 themselves use general resin films with excellent flexibility, such as polyester resins, polyphenylene sulfide resins, polyimide resins, and other general-purpose resin films. As the thickness of this resin film, what is 9 micrometers - 100 micrometers can be used. Examples of the polyester resin include resin materials such as polyethylene terephthalate resin, polyethylene naphthalate resin, and polybutylene naphthalate resin. Moreover, among these resin films, it is preferable to use a polyethylene terephthalate resin from viewpoints, such as an electrical characteristic, a mechanical characteristic, and cost.

Moreover, as an adhesive layer of the insulating layer 21,22, what consists of resin materials can be used, For example, the adhesive agent etc. which added the flame retardant to polyester resin or polyolefin resin are mentioned. The adhesive layer is formed with an appropriate thickness in the range of 10 μm to 150 μm. The insulating layers 21 and 22 are integrated by bonding the adhesive layers facing each other with the flat conductor 11 interposed therebetween, and bonding while being heated by a heating roller. In addition, a reinforcing plate may be provided on the side opposite to the exposed surface of the flat conductor 11 at the end of the cable. Furthermore, the insulating layers 21 and 22 may also be formed of single-layer resins such as polyethylene, polypropylene, polyimide, polyethylene terephthalate, polyester, or polyphenylene sulfide without using an adhesive layer. . In this case, the thickness of the resin can be set to about 300 μm, for example.

The ground conductor 31 is used, for example, in a two-layer structure in which metal foil such as aluminum foil or copper foil has a conductive adhesive layer. On the ground conductor 31 , a contact piece 32 is integrally provided according to the position of the ground line G of the flat conductor 11 , and is electrically connected to the flat conductor 11 which becomes the ground line G through the conductive adhesive layer provided on the contact piece 32 . In addition, the electrical connection between the contact piece 32 and the ground wire G may be solder, ultrasonic welding, laser welding, etc. in addition to using conductive bonding materials.

Regarding the shielding layer 41, when the overall thickness is about 30 μm, for example, when it is provided on the outer peripheral side of the ground conductor 31, a two-layer structure consisting of a metal layer and a conductive adhesive layer is used, and the conductive adhesive layer It is attached to the ground conductor 31 and the insulating layer 22 for the inner side. Although as the form of attachment, as shown in Fig. 1(A) and Fig. 1(B), one side of the exposed surface side of the flat conductor 11 is set so as to cover at least the entire outer peripheral side of the flat conductor 11, but It can also be installed over the entire circumference of the flat cable. Also, when the ground conductor 31 is provided on the outer peripheral side of the shield layer 41, a two-layer structure consisting of a metal layer and an adhesive layer is used. For example, an insulating layer such as PET may be provided on the surface of the aluminum foil to expose the aluminum foil at the connection portion with the ground conductor 31 at the end, and connect the exposed portion to the ground conductor 31 . Furthermore, as the shielding layer 41, in order to adjust the distance with the flat conductor 11, the three-layer structure which interposed the resin layer between the metal foil and the adhesive layer may be sufficient.

Next, an example of the manufacturing method of the shielded flat cable of this embodiment is demonstrated. 2 to 5 are views for explaining an example of the manufacturing process of the shielded flat cable according to the first embodiment of the present invention. In Fig. 2 to Fig. 5, (A) represents a view viewed from above, and (B) represents a cross-sectional view, for example, Fig. 2(B) is a cross-sectional view at 2B-2B in Fig. 2(A).

As shown in Fig. 2(A) and Fig. 2(B), a plurality of flat conductors 11 are arranged in parallel, so that the parallel surfaces are sandwiched between the insulating layers 21 and 22 with the bonding layer inside, while using The heating roller heats and joins, thereby manufacturing a long flat cable in which insulating layers 21 and 22 are bonded to both surfaces of the flat conductor 11 and integrated.

Next, as shown in FIG. 3(A) and FIG. 3(B) as its cross-sectional view at 3B-3B, for one of the insulating layers that become the terminals of the flat cable, here is the insulating layer 22 on the upper side, Only the width A of the terminal to be the end portion of the cable is removed by, for example, laser processing to expose the plurality of flat conductors 11 . In addition, in the case of manufacturing a plurality of shielded flat cables, in terms of improving manufacturing efficiency, the terminal portion at the rear end of the first shielded flat cable and the second shield connected to the shielded flat cable are simultaneously formed. The terminal portion at the front end of the flat cable is finally divided along the dividing line CC indicated by the chain line of two dots 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 twice the width A of the terminal at the end portion of the cable.

As a method of exposing the flat conductor 11 in a predetermined shape from an insulating layer 22, in addition to the method of providing an opening in the insulating layer 22 by laser processing as described above, it is also possible to preliminarily place the insulating layer 22 at a predetermined position. The method of setting the opening. In the latter case, it is sufficient to sandwich the flat conductor 11 between the insulating layer 21 and the insulating layer 22 provided with the opening to produce a flat cable, and then remove the connecting portion of the opening.

Next, as shown in FIG. 4(A) and FIG. 4(B) which is a cross-sectional view at 4B-4B thereof, the ground conductor 31 is attached to the outer peripheral side of the cable end side of the upper insulating layer 22 . In this case, the contact piece 32 of the ground conductor 31 is positioned so that it is located on the exposed surface of the flat conductor 11 to be the ground wire G, and the contact piece 32 is attached to the exposed surface of the flat conductor 11 . At this time, there is a step difference between the exposed surface of the flat conductor 11 and the upper surface of the insulating layer 22 , so the contact piece 32 is fixed to the exposed surface of the flat conductor 11 through the conductive adhesive layer in a bent state. The ground conductor 31 having the contact piece 32 can be obtained by stamping a metal foil provided with a conductive adhesive layer.

Next, as shown in FIG. 5(A) and FIG. 5(B) which is a cross-sectional view at 5B-5B thereof, the shielding layer 41 is attached to the grounding conductor in such a way that its conductive bonding layer faces the grounding conductor 31 side. 31 and the upper surface of the insulating layer 22. In this embodiment, the shielding layer 41 is provided only on one side of the insulating layer 22 side of the shielded flat cable 1, but it may be wound over the entire circumference including the upper and lower surfaces. Thereafter, in order to separate the front and rear shielded flat cables, the flexible flat cables are cut along the dividing line CC. In addition, the cutting of the flexible flat cable can also be performed before attaching the ground conductor 31 .

Although the case where the shield layer 41 is provided on the outer peripheral side of the ground conductor 31 has been described above, 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 shielding layer 41 is attached to the upper side of the insulating layer 22 , and then the grounding conductor 31 is provided on the upper side of the shielding layer 41 in an electrically connected state.

(Second Embodiment) 6 is a schematic view showing a shielded flat cable according to a second embodiment of the present invention, FIG. 6(A) is a perspective view, and FIG. 6(B) is a cross-sectional view at 6B-6B of FIG. 6(A). In the first embodiment, the shielding layer 41 is provided on one side of the shielded flat cable 1, but as shown in this embodiment, the shielding 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 opposite insulating layer 21 side and surrounds the outer peripheries of the insulating layers 21 and 22 . Furthermore, the shielding layers 41, 42 are provided on the outer peripheral sides of the insulating layers 22, 21, respectively. Thereby, the anti-noise characteristic can be improved. In addition, instead of providing the shielding layers 41 and 42 on each of the insulating layers 21 and 22, they may be provided so as to surround the entire circumference of the flat cable. Since the other configurations are the same as those of the first embodiment, description thereof will be omitted.

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

1‧‧‧Shielded flat cable 11‧‧‧Plane conductor 21, 22‧‧‧Insulation layer 31, 31'‧‧‧grounding conductor 32‧‧‧Contact sheet 41, 42‧‧‧shielding layer

Fig. 1 is a schematic view showing a shielded flat cable according to a first embodiment of the present invention. Fig. 2 is a diagram for explaining an example of the manufacturing process of the shielded flat cable according to the first embodiment of the present invention. Fig. 3 is a diagram for explaining an example of the manufacturing process of the shielded flat cable according to the first embodiment of the present invention. Fig. 4 is a diagram for explaining an example of the manufacturing process of the shielded flat cable according to the first embodiment of the present invention. Fig. 5 is a diagram for explaining an example of the manufacturing process of the shielded flat cable according to the first embodiment of the present invention. Fig. 6 is a diagram for explaining the outline of a shielded flat cable according to a second embodiment of the present invention.

1‧‧‧Shielded flat cable

11‧‧‧Plane conductor

21, 22‧‧‧Insulation layer

31‧‧‧Earth conductor

32‧‧‧Contact sheet

41‧‧‧shielding layer

A‧‧‧Width

Claims (5)

A shielded flat cable, which has a plurality of adjacent pairs of signal wires, a plurality of ground wires arranged between each pair of signal wires, a pair of insulating layers attached to the two sides of the juxtaposed surfaces of the above-mentioned signal wires and the above-mentioned ground wires, and a shielding layer covering at least one of the insulating layers, and the end of the cable in the length direction of one of the insulating layers is formed with the exposed cable end portion of the signal line and the grounding line, wherein the above-mentioned A ground conductor having a two-layer structure of a metal foil and a conductive adhesive layer is provided on the outer peripheral side of the cable end portion, and the ground conductor is electrically connected to the above-mentioned ground wires and the above-mentioned shielding layer. The above-mentioned conductive bonding layer is electrically connected to a plurality of contact pieces with the above-mentioned ground wires, and the above-mentioned pairs of signal wires are used for differential transmission. A shielded flat cable, which has a plurality of adjacent pairs of signal wires, a plurality of ground wires arranged between each pair of signal wires, a pair of insulating layers attached to the two sides of the juxtaposed surfaces of the above-mentioned signal wires and the above-mentioned ground wires, and a shielding layer covering at least one of the insulating layers, and the end of the cable in the length direction of one of the insulating layers is formed with the exposed cable end portion of the signal line and the grounding line, wherein the above-mentioned A grounding conductor is provided on the outer peripheral side of the end portion of the cable, the grounding conductor is provided so as to surround the entire circumference of the pair of insulating layers, and the grounding conductor is electrically connected to each of the grounding wires and the shielding layer, The shielding layer is provided on the outer peripheral side of each of the pair of insulating layers in contact with the grounding conductor, and the signal line and the grounding line are arranged such that one end is the signal line and the other end is the grounding line, The above pairs of signal lines are used for differential transmission. The shielded flat cable as described in Claim 2, wherein, The above-mentioned grounding conductor integrally has a contact piece electrically connected to each of the above-mentioned grounding wires. The shielded flat cable according to any one of claims 1 to 3, wherein the ground conductor is located between the insulating layer and the shielding layer. The shielded flat cable according to any one of claims 1 to 3, wherein the ground conductor is located on the outer peripheral side of the shielding layer.

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