Shielded flat cable

Abstract

To provide a shielded flat cable excellent in noise shielding property.SOLUTION: A shielded flat cable has: a plurality of conductors which ae arranged in parallel and include a ground wire; an insulator including a first insulator arranged on the top face of the plurality of conductors and a second insulator arranged on the bottom face of the plurality of conductors; a metal foil which is arranged on the first insulator, and electrically connected with the ground wire; and a shield layer which is electrically connected with the metal foil, and arranged so as to cover an outer periphery of the insulator and the metal foil.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a shielded flat cable. [Background technology]

[0002] Patent Document 1 discloses a bend-resistant shield-coated flexible flat cable in which a plurality of rectangular conductors are arranged at an arbitrary distance from each other and coated on the top and bottom with an insulating layer having an insulating adhesive layer, and the top and bottom surfaces of the flexible flat cable are coated with a shield coating material having an insulating layer as the outermost layer, a metal layer as the middle layer, and an insulating adhesive layer as the innermost layer, wherein any one or more of the rectangular conductors are used as ground conductors, and the metal layer of the shield coating material and the ground conductor are in contact at a predetermined location. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-93178 Summary of the Invention [Problem to be solved by the invention]

[0004] 2. Description of the Related Art Flexible flat cables have been conventionally used for internal wiring of various electronic devices and information devices for the purpose of space saving and easy connection.

[0005] Furthermore, from the viewpoint of preventing the influence of noise, a shielded flat cable, which is a flexible flat cable provided with a shield, has conventionally been used.

[0006] However, conventional shielded flat cables do not have sufficient noise shielding properties, and there has been a demand for shielded flat cables with excellent noise shielding properties.

[0007] Therefore, an object of the present disclosure is to provide a shielded flat cable with excellent noise shielding properties. [Means for solving the problem]

[0008] The shielded flat cable of the present disclosure includes a plurality of conductors arranged in parallel, including ground wires; an insulator including a first insulator arranged on the upper surfaces of the plurality of conductors and a second insulator arranged on the lower surfaces of the plurality of conductors; a metal foil arranged on the first insulator and electrically connected to the ground wires; and a shielding layer electrically connected to the metal foil and arranged to cover the outer periphery of the insulator and the metal foil. [Effects of the Invention]

[0009] According to the present disclosure, a shielded flat cable with excellent noise shielding properties can be provided. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view of a shielded flat cable according to one embodiment of the present disclosure taken along a plane perpendicular to the longitudinal direction. [Figure 2] FIG. 2 is a bottom view of a shielded flat cable according to one embodiment of the present disclosure. [Figure 3] FIG. 3 is a top view of a shielded flat cable according to one embodiment of the present disclosure. [Figure 4] FIG. 4 is a cross-sectional view of a shielded flat cable according to another embodiment of the present disclosure, taken along a plane perpendicular to the longitudinal direction. [Figure 5] FIG. 5 is a cross-sectional view of a shielded flat cable according to another embodiment of the present disclosure, taken along a plane perpendicular to the longitudinal direction. [Figure 6] FIG. 6 is a cross-sectional view of the shielded flat cable produced in Experimental Example 2, taken along a plane perpendicular to the longitudinal direction. [Figure 7] FIG. 7 is a bottom view of the shielded flat cable produced in Experimental Example 2. As shown in FIG. [Figure 8]FIG. 8 is a top view of the shielded flat cable produced in Experimental Example 2. As shown in FIG. [Figure 9] FIG. 9 shows the evaluation results of SSD21 in Experimental Examples 1 and 2. DETAILED DESCRIPTION OF THE INVENTION

[0011] The embodiments for carrying out the invention are described below.

[0012] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described. In the following description, the same or corresponding elements will be denoted by the same reference numerals, and the same description thereof will not be repeated.

[0013] (1) A shielded flat cable according to one embodiment of the present disclosure includes a plurality of conductors arranged in parallel, including a ground wire; an insulator including a first insulator arranged on the upper surface of the plurality of conductors and a second insulator arranged on the lower surface of the plurality of conductors; a metal foil arranged on the first insulator and electrically connected to the ground wire; and a shielding layer electrically connected to the metal foil and arranged to cover the outer periphery of the insulator and the metal foil.

[0014] In a shielded flat cable according to one embodiment of the present disclosure, the ground wire is connected to the shield layer via a metal foil. The ground wire can be easily connected to the metal foil provided on the first insulator by, for example, bending the ground wire. Furthermore, the metal foil and the shield layer can each have a planar shape, allowing for a sufficiently large connection area. This reduces the electrical resistance due to the connections between the ground wire, the metal foil, and the shield layer, thereby improving the noise shielding characteristics of the shielded flat cable.

[0015] (2) In the above (1), the ground line and the metal foil may be metallically connected.

[0016] The metallic connection between the ground wire and the metal foil reduces the electrical resistance between them. The connection area between the metal foil and the shielding layer can be made sufficiently large, which reduces the electrical resistance between the ground wire, metal foil, and shielding layer, thereby improving the noise shielding characteristics of the shielded flat cable.

[0017] (3) In the above (1) or (2), the ground line may be arranged at an end along the arrangement of the plurality of conductors.

[0018] By arranging the ground wire at the end of the arrangement of the multiple conductors, the ground wire can be easily connected to the metal foil, thereby increasing the productivity of the shielded flat cable.

[0019] (4) In any of the above (1) to (3), an intervening member may be disposed between the insulator and the metal foil.

[0020] The shielded flat cable according to one embodiment of the present disclosure has an interposer disposed between the insulator and the metal foil, which makes it possible to easily adjust the distance between the conductor and the metal foil and perform impedance matching.

[0021] (5) In (4), the intervening portion may be arranged in the area covered by the shielding layer so as to cover the plurality of conductors from a first end to a second end along the length of the conductors.

[0022] In the area covered with the shielding layer, by covering a plurality of conductors with an interposer from the first end to the second end, impedance matching can be achieved from the first end to the second end of the conductors.

[0023] (6) In any of (1) to (5) above, the ground wire may be divided into a plurality of members along its length, and the ends of the divisions may have bent portions that are bent so as to be positioned on the top surface of the metal foil and are metallically connected to the metal foil.

[0024] The bent portion of the ground wire allows the ground wire and the metal foil to be metallically connected, reducing the electrical resistance between the two components. Furthermore, the connection area between the metal foil and the shielding layer can be made sufficiently large, reducing the electrical resistance between the ground wire, metal foil, and shielding layer, thereby improving the noise shielding characteristics of the shielded flat cable.

[0025] (7) In (6), the ground line may have a plurality of the bent portions.

[0026] By providing the ground wire with multiple bent sections, the number of connection points between the ground wire and the metal foil is increased, the electrical resistance due to the connection between the ground wire and the metal foil is reduced, and the noise shielding characteristics of the shielded flat cable are improved.

[0027] (8) In the above (6) or (7), a spacer is disposed between the insulator and the metal foil, In a cross section perpendicular to the longitudinal direction of the shielded flat cable at a position including the bent portion, The folded portion may overlap the insulator, the filler, and the metal foil.

[0028] By overlapping the bent portion with the insulator, the filler, and the metal foil, the distance from the conductor to the bent portion can be stabilized, making it easier to achieve impedance matching.

[0029] (9) In any of the above (1) to (5), the ground wire may include multiple layers, and at one or both longitudinal ends, at least one of the layers may be bent to be positioned on the upper surface of the metal foil, and may have a bent portion that is metallically connected to the metal foil.

[0030] By providing a bent portion at the longitudinal end of the ground wire, the ground wire can be connected to the metal foil without dividing the ground wire, which reduces the number of steps required to manufacture the shielded flat cable and improves productivity.

[0031] (10) In any one of the above (1) to (9), the ground line has an exposed portion at least a part of which is exposed from the first insulator, The exposed portion of the ground line may be metallically connected to the metal foil.

[0032] The ground wire has an exposed portion that is exposed from the first insulator, and the exposed portion is connected to the metal foil, so that the ground wire and the metal foil can be connected more easily than if the ground wire were bent, thereby improving the productivity of the shielded flat cable.

[0033] (11) In any one of the above (1) to (10), in a cross section perpendicular to the longitudinal direction of the shielded flat cable, The metal foil may be disposed so as to cover at least the plurality of conductors excluding the ground line.

[0034] By arranging the metal foil so that it covers at least the conductors excluding the ground wire in a cross section perpendicular to the longitudinal direction of the shielded flat cable, the distance between the metal foil and the conductors excluding the ground wire can be made constant, thereby achieving impedance matching regardless of the conductor and reducing or eliminating impedance gaps that are a source of radiated noise.

[0035] [Details of the embodiments of the present disclosure] Specific examples of a shielded flat cable according to an embodiment of the present disclosure (hereinafter referred to as "the present embodiment") will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims. [Shielded flat cable] Fig. 1 shows a cross-sectional view of a shielded flat cable 10 according to this embodiment taken along a plane perpendicular to its longitudinal direction, Fig. 2 shows a bottom view of the shielded flat cable 10 according to this embodiment, and Fig. 3 shows a top view of the shielded flat cable 10 according to this embodiment. Fig. 1 corresponds to a cross-sectional view taken along line AA in Figs. 2 and 3.

[0036] 4 and 5 show modified shielded flat cables, and are cross-sectional views taken along a plane perpendicular to the longitudinal direction of the shielded flat cable.

[0037] Fig. 6 shows an example of the configuration of a conventional shielded flat cable, and is a cross-sectional view taken along a plane perpendicular to the longitudinal direction of the shielded flat cable. Fig. 7 shows a bottom view of the shielded flat cable 60 shown in Fig. 6, and Fig. 8 shows a top view of the shielded flat cable 60 shown in Fig. 6. Fig. 6 corresponds to a cross-sectional view taken along line BB in Figs. 7 and 8.

[0038] 1, 2, 3, 4, 5, 6, 7, and 8, the X axis is the axis along which the multiple conductors are arranged, the Y axis is the axis along which the thickness of the shielded flat cable 10 is arranged, and the Z axis is the axis along which the multiple conductors are arranged.

[0039] As described above, FIGS. 4 and 5 show modified examples, and FIGS. 6, 7, and 8 are explanatory diagrams of conventional configuration examples. Therefore, the following description will be given mainly using FIGS. 1 to 3, and will also use FIGS. 4 to 8 as necessary.

[0040] For ease of explanation, in this specification, the surface located above along the Y axis in Figures 1 to 8 may be referred to as the upper surface, and the surface located below as the lower surface. However, when using a shielded flat cable, the orientation of use changes depending on the device to which it is connected, and the above notation is not intended to limit use to a mode in which the upper surface is located above the lower surface.

[0041] The drawings are schematic diagrams used to explain the arrangement of each component of the shielded flat cable of the present embodiment, and do not accurately show the size ratios of each component.

[0042] Furthermore, in this specification, the names of components may be described with suffixes such as "first insulator" and "second insulator." The suffixes "first," "second," etc. are used merely to distinguish between components and to prevent confusion during description, and do not represent placement, priority, etc. Therefore, when there is no particular risk of confusion or when components are described together, they may simply be referred to as "insulator."

[0043] As shown in FIG. 1, the shielded flat cable 10 of this embodiment can have a plurality of conductors 11, an insulator 12, a metal foil 13, and a shielding layer 14. (1) About each component Each component will be described below. (1-1) Conductor The plurality of conductors 11 can be arranged in parallel with the longitudinal direction of the conductors 11 along the Z axis in Fig. 1. In Fig. 1, the plurality of conductors 11 are arranged along the X axis.

[0044] The multiple conductors 11 may include ground lines 111. In addition to the ground lines 111, the multiple conductors 11 may also include signal lines 112 that transmit electrical signals between connected devices, power lines (feed lines) that supply power to connected devices, etc. Due to space limitations, in Figure 1 and other figures, only some of the conductors 11 are indicated by reference numerals, but components of the same shape arranged along the X-axis are conductors 11.

[0045] Among the plurality of conductors 11, the arrangement of the ground wire 111 is not particularly limited, but in order to connect to the metal foil 13, it may be arranged at an end along the arrangement of the plurality of conductors 11.

[0046] By arranging the ground wire 111 at the end along the arrangement of the multiple conductors 11, i.e., at the end along the X-axis in Figure 1, the ground wire 111 can be easily connected to the metal foil 13, thereby improving the productivity of the shielded flat cable 10.

[0047] FIG. 1 shows an example in which a total of two ground wires 111 are arranged at both ends along the arrangement of the multiple conductors 11, but this is not limited to this form, and the number of ground wires 111 may be one, or three or more.

[0048] The shape of the multiple conductors 11 is not particularly limited, and can be one or more types selected from flat conductors (rectangular conductors), round conductors, and flat conductors, for example. A flat conductor refers to a conductor having a rectangular cross section perpendicular to its longitudinal direction. A flat conductor refers to a conductor having a thickness shorter than its width in a cross section perpendicular to its longitudinal direction, for example. A round conductor refers to a conductor having a circular cross section perpendicular to its longitudinal direction. A flat conductor refers to a conductor having a shape obtained by squashing a circle, for example, an ellipse in a cross section perpendicular to its longitudinal direction. A flat conductor can be a conductor having a thickness shorter than its width in a cross section perpendicular to its longitudinal direction, for example.

[0049] The material of the conductor 11 is not particularly limited, but may be copper, for example. As the copper, one or more types selected from soft copper and copper alloys may be used. The surface of the conductor 11 may be plated, for example, copper may be plated with nickel, tin, or silver.

[0050] The size of the conductor 11 is not particularly limited, but for example, if the conductor 11 is a flat conductor, the thickness may be 10 μm to 100 μm, and the width may be 0.2 mm to 0.8 mm. If the conductor 11 is a round conductor, the outer diameter may be 25 μm to 500 μm.

[0051] The conductors 11 may include conductors 11 of different sizes and shapes.

[0052] The pitch between the conductors 11 is not particularly limited, but can be, for example, 0.5 mm to 1.0 mm. The pitch between the conductors 11 means the distance between the centers of the conductors 11, specifically the distance between the centers along the width of the conductors 11.

[0053] The ground line 111 of the conductor 11 may be divided into a plurality of members along its length.

[0054] 2 and 3, the ground wire 111 may be cut at a cutting portion 22 and divided into multiple members such as a first member 111A, a second member 111B, and a third member 111C. FIG. 2 is a bottom view of the shielded flat cable 10, and FIG. 3 is a top view of the shielded flat cable 10. For this reason, the multiple conductors 11 cannot be directly seen in FIGS. 2 and 3, but in FIGS. 2 and 3, the state of the multiple conductors 11 is indicated by dotted lines so that it can be seen.

[0055] As shown in Figures 1 and 3, the ground line 111 may have a bent portion 111D at the end resulting from the split that is bent so as to be positioned on the upper surface 131 of the metal foil 13 and is metallically connected to the metal foil 13.

[0056] 3, the bent portion 111D can be electrically connected to a terminal 111E of the ground wire 111 exposed at the end portion 21, which is the end along the length of the shielded flat cable 10. Therefore, the shield layer 14 can be connected to the ground terminal of a device connected to the shielded flat cable 10 via the ground wire 111 and the metal foil 13.

[0057] The bent portion 111D of the ground wire 111 allows the ground wire 111 and the metal foil 13 to be metallically connected, thereby reducing the electrical resistance (connection resistance) between the two components. Furthermore, the connection area between the metal foil 13 and the shielding layer 14 can be made sufficiently large, which sufficiently reduces the electrical resistance between the ground wire 111, the metal foil 13, and the shielding layer 14, thereby improving the noise shielding characteristics of the shielded flat cable 10.

[0058] In this specification, the connection area between the metal foil 13 and the shield layer 14 means the area of ​​the region where the metal foil 13 and the shield layer 14 are electrically connected.

[0059] 3, the ground wire 111 may have multiple bent portions 111D. By having the ground wire 111 have multiple bent portions 111D, the number of connection points between the ground wire 111 and the metal foil 13 is increased, the electrical resistance due to the connection between the ground wire 111 and the metal foil 13 is reduced, and the noise shielding characteristics of the shielded flat cable 10 are improved.

[0060] In a cross section perpendicular to the longitudinal direction of the shielded flat cable 10 at a position including the bent portion 111D, the bent portion 111D may overlap the insulator 12, the filler 15, and the metal foil 13, as shown in Fig. 1. The bent portion 111D may overlap the conductor 11 other than the ground wire 111, that is, be bent so as to cross the conductor 11.

[0061] By overlapping the bent portion 111D with the insulator 12, the interposer 15, and the metal foil 13, the distance from the conductor 11 to the bent portion 111D can be stabilized, making it easier to achieve impedance matching. (1-2) Insulator The shielded flat cable 10 can have an insulator 12 including a first insulator 12A arranged on an upper surface 11X of the plurality of conductors 11 and a second insulator 12B arranged on a lower surface 11Y of the plurality of conductors 11.

[0062] As shown in FIG. 1, the first insulator 12A and the second insulator 12B can be in direct contact with each other and bonded together in the area where the conductor 11 is not disposed.

[0063] The upper surface 11X and the lower surface 11Y of the conductor 11 refer to the upper surface and the lower surface of the conductor 11 along the Y axis in FIG.

[0064] The configuration of the insulator 12 is not particularly limited, and the thickness and material of the insulator 12 can be selected depending on, for example, the magnitude of impedance required for the conductor 11 of the shielded flat cable 10.

[0065] The first insulator 12A and the second insulator 12B may each have, for example, a base material and an adhesive layer. When the first insulator 12A and the second insulator 12B have a base material and an adhesive layer, the first insulator 12A and the second insulator 12B may each be a laminate of the base material and the adhesive layer.

[0066] The material of the substrate is not particularly limited, but a material with excellent flexibility can be used. Using an insulator with excellent flexibility as the substrate material increases the flexibility of the shielded flat cable 10. The substrate material can be, for example, one or more types selected from polyester resin, polyphenylene sulfide resin, polyimide resin, etc. Examples of polyester resin include resin materials such as polyethylene terephthalate resin, polyethylene naphthalate resin, and polybutylene naphthalate resin. The thickness of each substrate can be, for example, 9 μm or more and 400 μm or less. The thickness and material of the substrate of the first insulator 12A and the second insulator 12B may be different or the same.

[0067] The insulator 12 may have an adhesive layer on the surfaces of the first insulator 12A and the second insulator 12B that face the conductor 11. By having the adhesive layer on the first insulator 12A and the second insulator 12B, for example, it is possible to sandwich a plurality of conductors 11 between them, with the adhesive layers of the first insulator 12A and the second insulator 12B facing each other, and bond them together by applying heat with a heating roller to bond them together, thereby integrating them.

[0068] The adhesive layer may be made of one or more materials selected from polyester resins, polyolefin resins, polyvinyl chloride, etc. Examples of polyolefin resins include polypropylene. The adhesive layer may contain additives such as flame retardants as needed. The thickness of each adhesive layer may be, for example, 3 μm to 200 μm. The thickness and material of the adhesive layer may be different or the same for the first insulator 12A and the second insulator 12B.

[0069] Since the conductor 11 and the insulator 12 do not have to be bonded together, the insulator 12 may have only a base material and not an adhesive layer.

[0070] As shown in Fig. 2, at the end portion 21, which is the end portion along the length of the shielded flat cable 10, the insulator 12 arranged on the upper surface 11X or the lower surface 11Y of the conductor 11 is removed to expose the conductor 11. Fig. 2 shows an example in which the second insulator 12B is removed at the end portion 21, but the first insulator 12A may be removed instead of the second insulator 12B to expose the conductor 11 at the end portion 21.

[0071] The terminal end 21 is a portion for connecting the shielded flat cable 10 to other devices, and may be provided with exposed conductors 11 and a connector for connecting other devices. In addition, a reinforcing member such as a reinforcing tape may be provided to reinforce the terminal end 21. (1-3) Metal foil The shielded flat cable 10 of this embodiment may have a metal foil 13 disposed on the first insulator 12A and electrically connected to the ground wire 111.

[0072] 6, 7, and 8, a conventional shielded flat cable 60 has a method in which a shielding layer 14 is placed on a conductor 11 that is folded back along the longitudinal direction of the conductor 11, and the conductor 11 and the shielding layer 14 are electrically connected with a conductive adhesive. The shielded flat cable 60 will be described in detail in Experimental Example 2.

[0073] However, the electrical resistance of conductive adhesives (conductive resins) is generally higher than that of metals, etc., which increases the electrical resistance between the conductor 11 and the shielding layer 14, making it difficult to sufficiently improve the noise shielding characteristics of the shielded flat cable 60.

[0074] In contrast to this, the shielded flat cable 10 of this embodiment has the metal foil 13, which makes it possible to metallically connect the ground wire 111 and the metal foil 13 without using a conductive adhesive.

[0075] As will be described later, a laminate of a metal layer 141 and a resin layer 142 can be used for the shielding layer 14, but because the shielding layer 14 has the resin layer 142, it has been difficult to metallically connect the ground line 111 to the metal layer 141. In contrast, the metal foil 13 does not include a resin layer, so it is possible to metallically connect it to the ground line 111.

[0076] Since the connection area between the metal foil 13 and the shielding layer 14 can be made sufficiently large, even when the metal foil 13 and the shielding layer 14 are bonded with a conductive adhesive, the electrical resistance value can be made sufficiently small, thereby improving the shielding characteristics of the shielded flat cable 10.

[0077] The metal foil 13 may have a structure in which no resin layer is disposed on the upper surface 131 and the metal is exposed. An adhesive for adhering to the insulator 12 or the interposer 15 may be disposed on the lower surface 132 of the metal foil 13. The material of the metal foil 13 is not particularly limited, and may be, for example, one or more types selected from copper, aluminum, and tin-plated copper.

[0078] In a cross section perpendicular to the longitudinal direction of the shielded flat cable 10, the metal foil 13 may be arranged so as to cover at least the conductors 11 excluding the ground wires 111, as shown in Fig. 1. Specifically, the metal foil 13 can be arranged so as to cover, for example, region R1 in Fig. 1. By arranging the metal foil 13 so as to cover at least the conductors 11 excluding the ground wires 111 in a cross section perpendicular to the longitudinal direction of the shielded flat cable 10, the distance L1 between the metal foil 13 and the conductors 11 excluding the ground wires 111 can be made constant. Therefore, impedance matching can be achieved regardless of the conductors 11, and impedance gaps, which are a source of radiation noise, can be reduced or eliminated.

[0079] As shown in FIG. 3 , the metal foil 13 may be provided in the region covered by the shielding layer 14 so as to completely cover the entire length of the multiple conductors 11, excluding at least the ground wire 111, from the first end 31A to the second end 31B without being interrupted at the cut portion 22. By covering the multiple conductors 11 along the length of the multiple conductors 11 with the metal foil 13 in the region covered by the shielding layer 14, the distance L1 between the multiple conductors 11 and the metal foil 13 can be made constant, and impedance matching can be achieved regardless of the conductor 11. In other words, impedance matching can be achieved from the first end 31A to the second end 31B for each conductor 11. This reduces or eliminates impedance gaps, which are a source of radiation noise.

[0080] In addition, in order to expose the conductors 11 at the end portion 21 and its vicinity, the metal foil 13 may be configured not to cover the plurality of conductors 11 . (1-3) Shield layer The shielded flat cable 10 of this embodiment may have a shielding layer 14 arranged to cover the outer periphery of the insulator 12 and the metal foil 13 .

[0081] Shield layer 14 may be disposed on the exterior of insulator 12 and metal foil 13, specifically on the exterior surface.

[0082] The shielding layer 14 can be electrically connected to the metal foil 13. A conductive adhesive can be disposed between the metal foil 13 and the shielding layer 14, and the metal foil 13 and the shielding layer 14 can be electrically connected by the conductive adhesive. Therefore, the shielding layer 14 is electrically connected to the ground line 111 by the metal foil 13.

[0083] In the shielded flat cable 10 of this embodiment, the ground wire 111 is connected to the shielding layer 14 via the metal foil 13. The ground wire 111 can be easily connected to the metal foil 13 provided on the first insulator 12A by, for example, bending the ground wire 111. Furthermore, the metal foil 13 and the shielding layer 14 can each have a planar shape, allowing for a sufficiently large connection area. This reduces the electrical resistance due to the connection between the ground wire 111, the metal foil 13, and the shielding layer 14, thereby improving the noise shielding characteristics of the shielded flat cable 10.

[0084] The shield layer 14 may have a metal layer 141, and may have a structure in which the metal layer 141 and a resin layer 142 are laminated together, as shown in FIG.

[0085] The metal layer 141 may be, for example, a metal foil, or a metal vapor deposition film formed on the resin layer 142. The material of the metal layer 141 may be any material as long as it has conductivity, and may be, for example, copper or aluminum, which are relatively inexpensive and have excellent conductivity.

[0086] The resin contained in the resin layer 142 is not particularly limited as long as it is a material that can support the metal layer 141, but examples thereof include polyester such as polyethylene terephthalate resin (PET) and polyethylene naphthalate resin (PEN).

[0087] The thickness of the shield layer 14 is not particularly limited, but can be, for example, 200 pm or more and 200 μm or less.

[0088] The shield layer 14 can be arranged such that the metal layer 141 is located inside the resin layer 142, i.e., the metal layer 141 is located closer to the multiple conductors 11 than the resin layer 142. Therefore, the resin layer 142 is located on the outside of the shielded flat cable 10, and may be the surface exposed to the outside.

[0089] An adhesive layer may be provided between the shield layer 14 and the insulator 12, if necessary.

[0090] From the viewpoint of improving workability, the adhesive placed between the shield layer 14 and the insulator 12 may also be a conductive adhesive. (1-4) Intervention The shielded flat cable 10 of this embodiment may also have an interposer 15 to adjust the distance between the conductor 11 and the shielding layer 14 or metal foil 13, which is a conductor arranged outside the conductor 11, and to adjust the impedance of the conductor 11.

[0091] In particular, from the viewpoint of adjusting the distance between the conductor 11 and the metal foil 13, the shielded flat cable 10 of this embodiment may have an interposer 15, specifically a first interposer 15A, arranged between the insulator 12 and the metal foil 13.

[0092] The shielded flat cable 10 of this embodiment includes the interposer 15 disposed between the insulator 12 and the metal foil 13, which allows for easy adjustment of the distance L1 between the conductor 11 and the metal foil 13 and impedance matching. As shown in FIG. 1, the interposer 15 may also be provided at the location where the bent portion 111D is provided. If FIG. 1 is a longitudinal cross section of FIG. 2, and FIG. 2 is a transverse cross section, i.e., a cross section parallel to the Z axis, the interposer 15 may also be provided at the location where the cut portion 22 is provided, so as to overlap with the multiple conductors 11. That is, as shown in FIG. 3, the interposer 15 may be provided in the area covered by the shielding layer 14 so as to cover the entire length of the multiple conductors 11 from the first end 31A to the second end 31B, without being interrupted by the cut portion 22, as with the metal foil 13. In the area covered by the shielding layer 14, by covering multiple conductors 11 with interposers 15 from the first end 31A to the second end 31B, impedance matching can be achieved from the first end 31A to the second end 31B of the conductors 11.

[0093] The first end 31A and the second end 31B refer to the ends along the length of the conductor 11 in the area covered with the shielding layer 14.

[0094] Examples of materials for the filler 15 include polyester resins and polyolefin resins. Examples of polyolefin resins include polyethylene and polypropylene. The filler 15 may contain additives such as flame retardants as needed. The thickness of the filler 15 can be selected depending on the characteristics required of the conductor.

[0095] 1 shows an example in which the shielded flat cable 10 has a first spacer 15A arranged above the conductor 11 and a second spacer 15B arranged below the conductor 11, but the present invention is not limited to this. The shielded flat cable 10 may have only one of the first spacer 15A and the second spacer 15B. When the shielded flat cable 10 has the first spacer 15A and the second spacer 15B, the first spacer 15A and the second spacer 15B may be made of the same material or may be different in size. (2) Connection between the ground wire and the metal foil The ground line 111 and the metal foil 13 can be electrically connected, and the form of the connection is not particularly limited, but they may be metallically connected.

[0096] In this specification, the ground line 111 and the metal foil 13 being metallically connected means that they are connected by a metal material, such as ultrasonic bonding or soldering, without using a resin such as a conductive adhesive. Note that bonding includes laser welding and direct bonding in addition to ultrasonic bonding and soldering.

[0097] The metallic connection between the ground wire 111 and the metal foil 13 reduces the electrical resistance due to the connection between the ground wire 111 and the metal foil 13. Furthermore, the connection area between the metal foil 13 and the shielding layer 14 can be made sufficiently large, which reduces the electrical resistance due to the connection between the ground wire 111, the metal foil 13, and the shielding layer 14, thereby improving the noise shielding characteristics of the shielded flat cable 10.

[0098] The ground line 111 and the metal foil 13 only need to be metallically connected.

[0099] For example, as shown in FIGS. 1 and 3, the ground line 111 can be divided into a first member 111A, a second member 111B, and a third member 111C. The ends resulting from the division may have bent portions 111D that are bent so as to be positioned on the upper surface of the metal foil 13 and are metallically connected to the metal foil 13. One bent portion 111D may be provided on each of the first member 111A and the third member 111C, and two bent portions 111D may be provided on the second member 111B. At least one bent portion 111D may be provided on any one of the first member 111A, the second member 111B, and the third member 111C.

[0100] Of the multiple conductors 11, the conductors 11 at both ends of the arrangement of the conductors 11 can also be used as ground lines. When the multiple conductors 11 include ground lines 111 at both ends, the ground lines 111 at both ends may each have the bent portion 111D, or only one of the ground lines 111 may have the bent portion 111D.

[0101] Up to this point, an example has been described in which the ground line 111 is divided into three members: a first member 111A, a second member 111B, and a third member 111C. However, the ground line 111 may be divided into two members along its length, or into four or more members. The ground line 111 does not have to be divided. In this case, the ground line 111 may include two or more layers, and at least one of the layers may have a bent portion 111D that is bent so as to be positioned on the upper surface 131 of the metal foil 13. When the ground line 111 has two layers, the layer closest to the metal foil 13 may have the bent portion 111D, and the layer farthest from the metal foil 13 may function as a terminal.

[0102] The bent portion 111D may be provided at one or both longitudinal ends of the ground wire 111. In a cross section of the shielded flat cable 60 perpendicular to the longitudinal direction at a position including the bent portion 111D, the bent portion 111D overlaps the two-layered ground wire 111, the insulator 12, and the metal foil 13. In other words, the bent portion 111D is bent along the Z-axis. By providing the bent portion 111D at an end along the longitudinal direction of the ground wire 111, the ground wire 111 and the metal foil 13 can be metallically connected without dividing the ground wire 111. This reduces the number of steps in manufacturing the shielded flat cable 10, thereby improving productivity.

[0103] As shown in the shielded flat cable 40 in Fig. 4 and the shielded flat cable 50 in Fig. 5, at least a part of the ground wire 111 may have an exposed portion 111X exposed from the first insulator 12A. The exposed portion 111X may be metallically connected to the metal foil 13.

[0104] The ground wire 111 has an exposed portion 111X exposed from the first insulator 12A, and the exposed portion 111X is connected to the metal foil 13, which makes it easier to connect the ground wire 111 and the metal foil 13 than when the ground wire 111 is bent. This improves the productivity of the shielded flat cable.

[0105] 4, the exposed portion 111X of the ground wire 111 that is exposed from the first insulator 12A is metallically connected to the metal foil 13 by the solder layer 41. Note that the ground wire 111 and the metal foil 13 may be connected by a metal material other than solder instead of the solder layer 41.

[0106] 5, the metal foil 13 is bent and connected to an exposed portion 111X, which is a portion of the ground wire 111 that is exposed from the first insulator 12A. The shielded flat cable 50 shown in FIG. 5 may be joined to the ground wire 111 by ultrasonic bonding, soldering, or the like. The shielded flat cable 40 and the shielded flat cable 50 shown in FIGS. 4 and 5 can be the same as the shielded flat cable 10 shown in FIG. 1 and the like, except for the connection form between the ground wire and the metal foil, and therefore a description thereof will be omitted.

[0107] However, for example, in order to increase the connection area between the ground line 111 and the metal foil 13, the width of the ground line 111 may be made wider than the width of the other conductors 11.

[0108] In addition, in the shielded flat cable 10 shown in FIG. 1 , the ground wire 111 is cut at the cutting portion 22 and divided into multiple components. However, in the shielded flat cable 40 and the shielded flat cable 50, the ground wire 111 may be a single continuous component. This is because the ground wire 111 does not need to be bent in the shielded flat cable 40 or the like. The number of exposed portions 111X per ground wire 111 may be one or two or more. The exposed portions 111X may be provided on the entire surface of the ground wire 111. Even when the exposed portions 111X are provided on the entire surface of the ground wire 111, the number of locations where the ground wire 111 and the metal foil 13 are metallically connected may be one or two or more. [Example]

[0109] Specific examples will be described below, but the present invention is not limited to these examples and includes equivalents and modifications within the scope of the effects of the present invention. (1) Evaluation method The Ssd21 was measured for the shielded flat cables produced in the following experimental examples.

[0110] Ssd21 indicates the amount of conversion of an input differential signal to a common mode signal at the output terminal. Therefore, when comparing Ssd21 with a conventional shielded flat cable, the wider the relatively low frequency range, the better the noise shielding characteristics.

[0111] The length of the shielded flat cable to be measured for Ssd21 was 3 m, and measurements were taken using a network analyzer (Keysight Corporation, Models M9037A and M9375A). (2) Shielded flat cable manufacturing conditions The following describes the conditions and results of Experimental Examples 1 and 2. Experimental Example 1 is an example, and Experimental Example 2 is a comparative example. [Experimental Example 1] A shielded flat cable 10 was produced, the cross section of which perpendicular to the longitudinal direction has the structure shown in Fig. 1. The shielded flat cable thus produced has a bottom surface and a top surface having the structures shown in Figs. 2 and 3, respectively.

[0112] The manufactured shielded flat cable 10 has multiple conductors 11 arranged in parallel, an insulator 12 including a first insulator 12A and a second insulator 12B, a metal foil 13, a shielding layer 14 arranged to cover the outer periphery of the insulator 12 and the metal foil 13, and an interposer 15. (conductor) The conductors 11 were flat copper conductors with a width of 0.3 mm and a thickness of 0.035 mm. The conductors 11 were arranged so that the center-to-center distance between adjacent conductors 11 was equal, and the conductors 11 at both ends of the arrangement were used as ground lines 111.

[0113] 2 and 3, the ground wire 111 is cut at the cutting portion 22 and divided into a plurality of members, such as a first member 111A, a second member 111B, and a third member 111C, along the length of the ground wire 111. Then, as shown in FIGS. 1 and 3, the ground wire 111 has a bent portion 111D at the end resulting from the division, which is bent so as to be positioned on the upper surface 131 of the metal foil 13 and is metallically connected to the metal foil 13. The bent portion 111D is joined to the metal foil 13 by soldering.

[0114] As shown in FIG. 3, each ground wire 111 has four bent portions 111D, and each ground wire 111 is joined to the metal foil 13 at four locations. (insulator) A first insulator 12A is disposed on the upper surface 11X of the plurality of conductors 11, a second insulator 12B is disposed on the lower surface 11Y of the plurality of conductors 11, and the first insulator 12A and the second insulator 12B are bonded together to form the insulator 12. The first insulator 12A and the second insulator 12B are bonded together and in direct contact with each other in areas where the conductors 11 are not disposed.

[0115] The first insulator 12A and the second insulator 12B each have a base material and an adhesive layer. The first insulator 12A and the second insulator 12B have the same structure and material, and both use a base material made of polyethylene terephthalate with a thickness of 11 μm. The adhesive layer is made of polypropylene with a thickness of 5 μm.

[0116] 2, at the end portion 21, which is the end portion along the length of the shielded flat cable 10, the second insulator 12B arranged on the underside 11Y of the conductor 11 is removed to expose the end portion along the length of the conductor 11. For example, the bent portion 111D of the ground wire 111 and the terminal 111E of the ground wire 111 exposed at the end portion 21 are located at both ends of the first member 111A and are electrically connected to each other. (metal foil) Copper foil was used as the metal foil 13. As shown in Fig. 1, the metal foil 13 was arranged so as to cover a region R1 in which the multiple conductors 11, excluding the ground wires 111, were arranged in a cross section perpendicular to the longitudinal direction of the shielded flat cable 10. Furthermore, as shown in Fig. 3, in the region covered by the shielding layer 14, the metal foil 13 completely covers the multiple conductors 11, excluding the ground wires 111, from the first end 31A to the second end 31B along the longitudinal direction of the multiple conductors 11. (intervention) A first insulator 15A and a second insulator 15B were respectively disposed on the upper surface of the first insulator 12A and the lower surface of the second insulator 12B, as shown in Fig. 1. The first insulator 15A was disposed between the first insulator 12A and the metal foil 13.

[0117] The intervening material was polyethylene.

[0118] 1, the interposer 15 is arranged so as to cover a region R1 in which the plurality of conductors 11, excluding the ground wires 111, are arranged in a cross section perpendicular to the longitudinal direction of the shielded flat cable 10. Also, as shown in FIG. 3, the interposer 15 entirely covers the plurality of conductors 11, excluding the ground wires 111, from the first end 31A to the second end 31B along the longitudinal direction of the plurality of conductors 11 in the region covered by the shielding layer 14. (shield layer) A shielding layer 14 was disposed on the outside of the insulator 12 .

[0119] 1, the shield layer 14 is disposed so as to cover the outer periphery of the insulator 12 and the metal foil 13. A conductive adhesive is disposed on the surface of the shield layer 14 facing the metal foil 13, and the metal foil 13 and the metal layer 141 of the shield layer 14 are connected by the conductive adhesive.

[0120] 1, the shielding layer 14 has a structure in which a metal layer 141 and a resin layer 142 are laminated together, with aluminum foil being used for the metal layer 141 and polyethylene terephthalate (PET) being used for the resin layer 142. The thickness of the shielding layer 14 was 9 μm. The shielding layer 14 was arranged so that the metal layer 141 was on the inside, i.e., facing the multiple conductors 11.

[0121] The shielded flat cable 10 thus obtained was evaluated for SSD21. The evaluation results are shown in FIG. [Experimental Example 2] A shielded flat cable 60 was produced, the cross section of which perpendicular to the longitudinal direction has the structure shown in Fig. 6. The shielded flat cable 60 thus produced has a bottom surface and a top surface having the structures shown in Figs. 7 and 8, respectively.

[0122] The manufactured shielded flat cable 60 has multiple conductors 11 arranged in parallel, an insulator 12 including a first insulator 12A and a second insulator 12B, and a shield layer 14 arranged to cover the outer periphery of the insulator 12.

[0123] As shown in FIG. 7 , the shielded flat cable 60 has a window 71 on its underside, where the second insulator 12B has been removed. The ground wire 111 is cut at the window 71, dividing the ground wire 111 into a first member 111A, a second member 111B, and a third member 111C. The first member 111A and the third member 111C of the cut ground wire 111 are folded back along the longitudinal direction of the ground wire 111 together with the first insulator 12A. The ground wire 111 is positioned second from both ends along the arrangement of the multiple conductors 11. An insulator made of the same material as the second insulator 12B is again placed in the window 71. Because of the presence of the window 71, no interposer 15 is provided where the window 71 is located, as viewed in cross section in FIG. 7 . This means that the conductors 11 have portions where impedance matching is not achieved.

[0124] Therefore, as shown in FIG. 6, in a cross section perpendicular to the longitudinal direction of the shielded flat cable 60, a third insulator 12C, which is the folded-back first insulator 12A, is arranged on the first insulator 12A, and a folded-back portion 61, which is a further folded-back ground wire 111, is arranged.

[0125] The shield layer 14 is disposed so as to cover the outer periphery of the insulator 12 and the folded portion 61. A conductive adhesive is disposed on the surface of the shield layer 14 facing the folded portion 61, and the folded portion 61 and the metal layer 141 of the shield layer 14 are connected by the conductive adhesive.

[0126] Other than the above-described structure, the shielded flat cable 60 uses the same materials and members as the shielded flat cable 10 of Experimental Example 1, and therefore a description thereof will be omitted.

[0127] The SSD21 was evaluated for the obtained shielded flat cable 60. The evaluation results are shown in FIG.

[0128] 9, it was confirmed that the shielded flat cable 10 of Experimental Example 1 had improved SSD21 measurements across almost the entire frequency range compared to the shielded flat cable 60 of Experimental Example 2. In a significant frequency band, it was confirmed that the shielded flat cable 10 of Experimental Example 1 was 20 dB lower than the shielded flat cable 60 of Experimental Example 2. Therefore, it was confirmed that the shielded flat cable structure of Experimental Example 1, in which the metal foil 13 is disposed between the ground wire 111 and the shielding layer 14 and connected, can provide a shielded flat cable with excellent noise shielding characteristics. [Explanation of symbols]

[0129] 10 Shielded flat cable 11 Conductor 111 Grand Line 111A First member 111B Second member 111C Third component 111D Bending section 111E terminal 111X Exposed part 112 signal line 11X Top 11Y Bottom 12 Insulators 12A First Insulator 12B Second insulator 13 Metal foil 131 Top surface 132 Bottom surface 14 Shielding layer 141 Metal layer 142 Resin layer 15 Intervention 15A 1st intervention 15B 2nd intervention L1 distance R1 area 21 End 22 Cut section 31A 1st end 31B 2nd end 40 Shielded Flat Cable 41 Solder layer 50 Shielded Flat Cable 60 Shielded Flat Cable 61 Folded section 12C third insulator 71 Window

Claims

1. A plurality of conductors including a ground line arranged in parallel; an insulator including a first insulator disposed on an upper surface of the plurality of conductors and a second insulator disposed on a lower surface of the plurality of conductors; a metal foil disposed on the first insulator and electrically connected to the ground line; a shielding layer electrically connected to the metal foil and arranged to cover the outer periphery of the insulator and the metal foil.

2. 2. The shielded flat cable according to claim 1, wherein the ground wire and the metal foil are metallically connected.

3. 3. The shielded flat cable according to claim 1, wherein the ground wire is disposed at an end of the plurality of conductors along an arrangement thereof.

4. 3. The shielded flat cable according to claim 1, further comprising a filler disposed between the insulator and the metal foil.

5. 5. The shielded flat cable according to claim 4, wherein the filler is arranged to cover the plurality of conductors from a first end to a second end along the length of the conductors in the area covered by the shielding layer.

6. 3. The shielded flat cable according to claim 1, wherein the ground wire is divided into a plurality of members along its length, and each end of the divided members has a bent portion that is bent so as to be positioned on an upper surface of the metal foil and is metallically connected to the metal foil.

7. The shielded flat cable according to claim 6 , wherein the ground wire has a plurality of the bent portions.

8. a separator disposed between the insulator and the metal foil; In a cross section perpendicular to the longitudinal direction of the shielded flat cable at a position including the bent portion, The shielded flat cable according to claim 6 , wherein the bent portion overlaps the insulator, the filler, and the metal foil.

9. 3. The shielded flat cable according to claim 1, wherein the ground wire includes a plurality of layers, and at one or both longitudinal ends thereof, at least one of the layers is bent to be positioned on an upper surface of the metal foil and to be metallically connected to the metal foil.

10. the ground line has an exposed portion at least a part of which is exposed from the first insulator; 3. The shielded flat cable according to claim 1, wherein the exposed portion of the ground wire is metallically connected to the metal foil.

11. In a cross section perpendicular to the longitudinal direction of the shielded flat cable, 3. The shielded flat cable according to claim 1, wherein the metal foil is disposed so as to cover the plurality of conductors excluding at least the ground wire.

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