JPH06119821A - Flexible wiring sheet - Google Patents

Abstract

PURPOSE:To provide a flexible wiring sheet having structure where a wiring pattern required for an earth treatment can be simplified and a stable electromagnetic shield effect can be securely exhibited. CONSTITUTION:A plurality of conductors 13a-13c are formed on both surfaces of a long-sized sheet 12 having flexibility. A first insulative layer 14 is formed in such a manner as to cover the conductors 13a-13c. The first insulative layer 14 is covered with a shield layer 15 made of a conductive material. A second insulative layer 16 is formed on the shield layer 15. At least one cut portion 16a is formed on a part of the second insulative layer 16 so that a shield layer portion 15a is exposed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible wiring sheet used for connection in electronic equipment or between equipments, and more particularly to a flexible wiring sheet having an electromagnetic shield layer.

[0002]

2. Description of the Related Art Conventionally, in various electronic devices such as office automation equipment, flexible wiring sheets have been frequently used for connection inside and between devices. Some flexible wiring sheets of this type are provided with a shield layer in order to prevent radiation of electromagnetic noise to the outside and transfer from the outside.

FIG. 4 is a sectional view showing a conventional flexible wiring sheet having a shield layer. The flexible wiring sheet 1 has a long sheet 2 having flexibility. The long sheet 2 is made of, for example, an insulating resin. On the upper surface of the sheet 2, a plurality of elongated conductors 3a to 3d are formed so as to extend between both ends of the sheet 2. The conductors 3a to 3d are formed, for example, by bonding metal foils and then etching, or by plating or the like. An insulating film 4 made of synthetic resin or the like is attached to the upper surface of the sheet 2 so as to cover the conductors 3a to 3d. Then, the sheet 2, the conductor 3a to
A shield layer 5 is formed on the periphery so as to surround 3d and the insulating film 4. The shield layer 5 is made of a conductive material such as metal, and is provided to prevent the transfer of electromagnetic noise from the surroundings or to prevent the electromagnetic noise from being radiated from the conductors 3a to 3d to the surroundings. Has been. An insulating paint 6 is applied around the shield layer 5 to ensure insulation from the outside.

In use, the conductors 3a to 3d at both ends of the flexible wiring sheet 1 are electrically connected to a connector or the like of a device to be connected. In addition, the shield layer 5
Are exposed at both ends or one end of the flexible wiring sheet 1 and are electrically connected to the ground potential of the device to be connected.

[0005]

As described above, in the flexible wiring sheet 1, the above-mentioned electromagnetic shielding effect is obtained by connecting the shield layer 5 to the ground potential. Therefore, due to the electromagnetic shield effect, radiation of electromagnetic wave noise from the conductors 3a to 3d and exchange of electromagnetic wave noise from the outside are temporarily prevented.

However, since the shield layer 5 is used by being connected to the ground potential at one end or both ends of the flexible wiring sheet 1, the flexible wiring sheet 1 is connected when electrically connecting the shield layer 5 to the ground potential. There has been a problem that not only the signal line but also the earth line must be routed and formed in the proper portion.

Further, although the shield effect of the shield layer 5 has a temporary noise removing effect, it may not be possible to obtain a sufficient noise removing effect. An object of the present invention is to provide a flexible wiring sheet which can simplify wiring for grounding, has an electromagnetic shielding effect, and has a sufficient electromagnetic noise removing effect regardless of its length. .

[0008]

According to the present invention, a long sheet having flexibility, at least one long conductor formed on one side of the sheet, and one side of the sheet are provided. A first insulating layer formed so as to cover the elongated conductor, a shield layer formed on the first insulating layer and made of a conductive material, and formed on the shield layer A flexible wiring sheet comprising a second insulating layer, wherein at least one notch or opening is formed in the second insulating layer so as to expose a part of the shield layer. is there.

[0009]

A notch or an opening is formed in the second insulating layer to expose a part of the shield layer to the outside. Therefore,
The shield layer can be connected to the reference potential by electrically connecting the exposed shield layer portion to an exposed metal portion such as the chassis of the device. Moreover, since the flexible wiring sheet has sufficient flexibility, even if the exposed metal portion of the chassis is small, the shield layer can be reliably connected to the metal portion as described above.

Further, since the exposed part of the shield layer can be easily connected to the exposed metal part of the device, even if the length of the flexible wiring sheet is long, the shield layer is formed in the middle part thereof. It can be more reliably electrically connected to the ground potential, and a stable ground can be obtained. Further, a capacitor is obtained between the shield layer and the conductor via the first insulating layer, and a distributed constant type LC circuit is formed together with the inductance of the conductor, so that a more sufficient noise removal effect is obtained.

Further, if the exposed portion of the shield layer is used to connect to the ground potential, it is not always necessary to electrically connect the shield layer to the ground potential at the end of the flexible wiring sheet. . Therefore, it is possible to simplify the wiring for the grounding process at the connecting portion such as the substrate.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be clarified by describing the embodiments of the present invention. FIG. 1 is a partially cutaway perspective view showing a flexible wiring sheet according to an embodiment of the present invention. The flexible wiring sheet 11 includes a long sheet 12 having flexibility. The sheet 12 is made of an insulating resin, for example, and is configured to have flexibility as a whole. On the upper surface of the sheet 12, elongated conductors 13 a to 13 c are extended in parallel with the longitudinal direction of the sheet 12. The conductors 13a to 13c can be formed by pasting a metal foil such as a copper foil on the upper surface of the sheet 12 and then etching, or by a method of coating and hardening a plating or a conductive paste.

Conductors 13a to 13 are provided on the upper surface of the sheet 12.
A first insulating layer 14 is formed so as to cover c. In the embodiment, the first insulating layer 14 is made of a material in which dielectric powder is dispersed in an insulating resin. This is because, as will be described later, the first insulating layer 14 configures a capacitor between the conductors 13a to 13c and the shield layer 15 in a distributed constant manner. The first insulating layer 14 may be made of only an insulating resin without containing the dielectric powder as described above as long as a desired capacitance can be realized.

A shield layer 15 is formed on the upper surface of the first insulating layer 14. The shield layer 15 is formed by attaching a metal foil to the upper surface of the first insulating layer 14 or by applying a metal material by an appropriate method such as plating. The second insulating layer 16 is formed on the upper surface of the shield layer 15. The second insulating layer 16 is formed by applying an insulating paint or bonding an insulating film. A notch 16a is formed in a part of the second insulating layer 16 so that the shield layer portion 15a is exposed to the outside.

Although the second insulating layer 16 is formed only on the upper surface of the shield layer 15 in FIG. 1, both ends and the notch 16a of the flexible wiring sheet of this embodiment are formed.
It may be formed so as to cover the entire remaining portion except for. Similarly, with respect to the shield layer 15, as in the case of the flexible wiring sheet 1 shown in FIG.
It may be formed so as to surround the periphery of a to 13c and the first insulating layer 14 or the like, or may have a structure in which the shield layer 15 is laminated on the lower surface side of the sheet 12.

That is, as long as the radiation of the electromagnetic wave noise from the conductors 13a to 13c can be suppressed and the transmission and reception of the electromagnetic wave noise from the outside can be prevented, the shield layer 15 is the conductor 13.
It is preferable to dispose the conductors 13a to 13c so as to surround the conductors 13a to 13c in an insulated state from the a to 13c, and to electrically insulate the shield layer 15 from the outside, the second insulating layer 16 is formed of Is preferably formed so as to cover.

In the flexible wiring sheet 11 of this embodiment, a cutout 16a is formed in a part of the second insulating layer 16 to expose the shield layer portion 15a. Therefore, the shield layer 15 can be electrically connected to the ground potential by electrically connecting the shield layer portion 15a to the chassis of the device or the like. In particular, as shown in FIG. 2, even when the chassis 20 and the board 21 of the device are separated from each other, the flexible wiring sheet 11 has sufficient flexibility so that it is exposed at the portion indicated by the arrow A in the figure. The shield layer portion 15a formed can be connected to the chassis 20 by a conductive adhesive, solder, or the like.

Therefore, even if the total length of the flexible wiring sheet 11 is long, the ground potential can be stably applied to the shield layer 15. In addition, the shield layer portion 15
Since the shield layer 15 can be electrically connected to the ground potential in a, it is not always necessary to form the wiring pattern for connecting the shield layer 15 to the ground potential on the substrate 21 at both end portions of the flexible wiring sheet 11. Absent. Therefore, it is possible to simplify the ground wiring pattern in the portion to which the flexible wiring sheet 11 is electrically connected.

Further, in this embodiment, the first insulating layer 14
Is composed of the dielectric-containing resin as described above, a capacitor is distributed-constantly formed over the entire length of the flexible wiring sheet 11 between the conductors 13a to 13c and the shield layer 15. On the other hand, the conductors 13a to 13c themselves have an inductance component. Therefore, when the flexible wiring sheet 11 is viewed as a whole, a large number of LC filters are distributedly distributed, as shown in an equivalent circuit in FIG. 3, so that the electromagnetic wave noise can be reliably absorbed without separately connecting a noise filter. You can do it.

However, the dielectric powder may not be dispersed in the first insulating layer 14 as described above. That is, since the insulating material forming the first insulating layer 14 has a dielectric property itself, it has a tentative capacitance even if it does not contain a dielectric powder. Therefore, even if the dielectric powder is not included and the capacitor shown in FIG. 3 is not positively constructed, the LC circuit is constructed over the entire length of the flexible wiring sheet 11. Therefore, the flexible wiring sheet 11 of the present invention can obtain a sufficient noise removing effect without containing the dielectric powder.

The notch 16a shown in FIG. 1 can be formed at any position between both ends of the flexible wiring sheet 11, but when the length of the flexible wiring sheet 11 is long, the notch 16a is formed at the center between both ends. It is preferably provided in the vicinity. This is because the ground potential can be stably applied to the shield layer 15 over the entire length of the flexible wiring sheet 11. Further, instead of the notch 16a, an opening having an arbitrary shape may be formed. Even in that case, since a part of the shield layer 15 is exposed by the opening, the shield layer 15 is formed in the same manner as in the above embodiment. A stable ground potential can be applied to the.

[0022]

According to the present invention, a notch or an opening is formed in at least one portion of a part of the second insulating layer to expose a part of the shield layer. Therefore, by electrically connecting the exposed portion of the shield layer to the chassis of the device or the like, the ground potential can be stably and reliably applied to the shield layer. Therefore, even when the length of the flexible wiring sheet is long, the shield layer can be reliably electrically connected to the ground potential in the middle portion of the flexible wiring sheet, and a stable ground can be obtained. It is possible to exert a further electromagnetic shield effect.

Further, since the flexible wiring sheet has sufficient flexibility, the exposed portion of the shield layer can be easily joined to the metal portion even when the exposed metal portion of the equipment chassis is small. can do. Further, when the exposed portion of the shield layer is electrically connected to the chassis of the device or the like, it is not always necessary to electrically connect the shield layer to the ground pattern or the like at the end of the flexible wiring sheet. Therefore, it is possible to simplify the wiring pattern for grounding on the substrate.

Further, since the first insulating layer disposed between the shield layer and the conductor has a dielectric property, a large number of distributed constants are distributed over the entire length of the flexible wiring sheet together with the inductance of the conductor itself. An LC circuit is constructed. Therefore, the LC circuit exhibits a sufficient noise removing effect. Therefore, according to the present invention, it is possible to provide a flexible wiring sheet having a sufficient electromagnetic noise removing effect regardless of the length.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing a flexible wiring sheet of an embodiment.

FIG. 2 is a cross-sectional view for explaining a state in which the flexible wiring sheet of the example is connected to a board and a chassis of a device.

FIG. 3 is a circuit diagram showing an equivalent circuit of a flexible wiring sheet of an example.

FIG. 4 is a cross-sectional view of a conventional flexible wiring sheet.

[Explanation of symbols]

 11 ... Flexible wiring sheet 12 ... Sheets 13a to 13c ... Conductor 14 ... First insulating layer 15 ... Shield layer 15a ... Shield layer portion 16 ... Second insulating layer 16a ... Notch

Claims (1)

[Claims] 1. An elongated sheet having flexibility, at least one elongated conductor formed on one surface of the sheet, and one surface of the sheet covered with the elongated conductor. A first insulating layer formed as described above, a shield layer formed on the first insulating layer and made of a conductive material, and a second insulating layer formed on the shield layer. A flexible wiring sheet comprising at least one notch or opening formed in the second insulating layer so as to expose a part of the shield layer.