JP2008243665A - Shield flexible flat cable in which characteristic impedance matching is possible - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shield flat cable in which an advantage of the flat cable such as flexibility and simple and convenient connectivity is not lost, in which characteristic impedance matching is possible, which is superior in conductor width precision and pitch precision, and in which many processes and a great time are not required for manufacturing. <P>SOLUTION: A metal foil (2a) on one face formed on an insulating film (1) of a base material is removed in plural numbers of parallel linear forms by etching, plural numbers of parallel linear form metal foil pieces are made to remain to become a signal line (2) row, the metal foil (3a) on the other face is removed by numerous round holes (h1) by etching, repeated patterned arrangement of the metal foil body of the foil removed part is made to remain to make a shield layer (3), an insulating film (4a, 4b) is covered on the signal line row face and a shield layer face while leaving terminal exposed parts (t, t), and the shield flat cable (10) is obtained in which the characteristic impedance matching is possible. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a flexible flat cable (hereinafter abbreviated as a flat cable), and more particularly to a shielded flexible flat cable (hereinafter abbreviated as a shielded flat cable) capable of matching characteristic impedance.

Flat cables are frequently used as printed boards for electronic devices, internal wiring materials, or internal wiring materials for automobiles because of the space saving and simple connection of wiring materials. A conventional flat cable has a structure in which a plurality of conductors are arranged in parallel between two insulating films with both end portions of the conductors exposed, and a wiring method combining this flat cable and an insertion type connector. Is popular. An example of a conventional flat cable will be described with reference to FIG.
Two insulating films (4 ′, 4 ′) having a heat-fusible adhesive layer (not shown) on one side are provided with adhesive layer surfaces on the inner side, and a plurality of flat conductors (2 ′) are provided therebetween. It is preferably arranged in parallel with the interval (pitch) (p), the conductors (2 ′) at both ends are exposed for a predetermined length, and the connection terminal portions (terminal conductor exposed portions) (t, t) are provided and heat-sealed. Has a flat cable (50) with a reinforcing tape (U) attached to the connection terminal (t, t). This conventional flat cable is described in Patent Document 1 below. Although not shown, a shielded flat cable in which a metal foil film such as an aluminum PET (polyethylene terephthalate) film is bonded to one side or both sides of the flat cable to provide a shield layer is also described in Patent Document 2 below. .
JP 2001-43743 A JP-A-5-242736

In recent years, high-speed transmission cables have been widely used in electronic devices, but flat cables have also been used as high-speed transmission cables for liquid crystal, flat TV image interfaces, internal wiring materials, and the like. In order to use a flat cable as a high-speed transmission cable, it is important to match the characteristic impedance to a target value, and the characteristic impedance value is often required to be 100Ω. Usually, the flat cable is a shielded flat cable having a structure in which one surface or both surfaces of the flat cable are covered with a metal foil film such as an aluminum PET film over almost the entire area, and the value of the characteristic impedance is lowered by covering the flat cable with the metal foil film.
In conventional shielded flat cables, when the characteristic impedance value is smaller than the target value, an insulation film between the flat conductor of this flat cable and the metal foil film is usually used to match the characteristic impedance to the target value. A method of increasing the distance between the two by increasing the thickness or a method of reducing the width of the flat conductor has been taken. However, when the width of the flat conductor is reduced, there is a problem that the conductor width accuracy and pitch accuracy for fitting with the connector become strict and the dimensional accuracy of the connector becomes strict. Moreover, when the insulating film between the flat conductor and the metal foil film is made thick, the cable itself becomes thick, so that the flat cable becomes hard, and there is a problem that the advantage of the flat cable called flexibility is reduced. That is, there is a problem that a large number of shielded flat cables with severe fitting accuracy due to poor flexibility and a narrow conductor width can be seen.
The shield flat cable manufacturing method also requires conductor drawing, conductor rolling, conductor alignment, conductor lamination, shield tape lamination, signal line formation and shield layer formation, and in particular, alignment of thin wire conductors and shield tape lamination. It took a lot of time.
The present invention has been made in order to solve the various problems of the prior art described above, and it is possible to match the characteristic impedance without losing the advantages of the flat cable of flexibility and simple connectivity, and the conductor width. An object of the present invention is to provide a shielded flat cable which has good accuracy and pitch accuracy and does not require many steps and a great amount of time as described above for the production of a shielded flat cable.

As a first aspect, the present invention provides a plurality of parallel strips of metal foil on one side (signal line forming surface) of a metal foil formed on both surfaces of an insulating film of a base material by etching. The signal strips are formed by leaving the parallel metal foil strips in parallel to each other, and the foil foil is removed by removing a part of the metal foil on the other surface (shield layer forming surface) in an arbitrary shape by etching. The shield layer is formed by leaving the metal foil body provided with an insulating film, and the terminal line exposed surface is covered with an insulating film, and the shield layer surface is left exposed or insulated over the entire surface. A shielded flat cable coated with a film, wherein the characteristic impedance is matched to a target value due to the fact that the covering area of the metal foil of the shield layer facing the signal line row is reduced. In the shield flat cable capable characteristic impedance matching to symptoms.
Examples of the insulating film for the substrate include a PET film. Moreover, as said metal foil, copper foil is mentioned, for example. Moreover, the said linear metal foil piece is used as a conductor, for example, is a rectangular conductor shape. The etching may be performed by a general processing method such as masking printing, etching processing, and masking material removal.
The characteristic impedance matching will be described. The characteristic impedance can be adjusted by the covering area of the metal foil of the shield layer covering (facing) each signal line (the larger the covering area, the lower the characteristic impedance value, and the smaller the covering area, the characteristic impedance value) Goes up). For example, for two signal lines, if the covering area of the metal foil is large and the other is small, the characteristic impedance is small in the former and the latter is large, so that the matching is achieved. It cannot be said that there is. Therefore, in order to match the characteristic impedance to the target value, it is important to adjust the metal foil of the shield layer so as to have a uniform covering area for any of the plurality of signal lines.
With the shielded flat cable of the first aspect, the characteristic impedance can be matched without losing the advantages of the flat cable such as flexibility and simple connectivity, and the conductor width accuracy and pitch accuracy are good. This eliminates the need for many processes and a great deal of time.

As a second aspect of the present invention, the foil removing portion has a round hole with a diameter (maximum diameter) (hereinafter abbreviated as a diameter) of 0.2 mm to 2.0 mm, or a length with respect to the cable longitudinal direction of 0. A shielded flexible flat cable capable of matching characteristic impedance, characterized in that it is a polygonal hole of 2 mm to 10 mm, and these foil removing portions are arranged in an arbitrary arrangement.
Examples of the round hole include a round hole, an elliptical hole, and an oval hole. Examples of the polygonal holes include square holes such as triangular holes, square holes, rectangular holes, and trapezoidal holes, pentagonal holes, hexagonal holes, and the like.
In the shielded flat cable according to the second aspect, in addition to the function and effect of the shielded flat cable according to the first aspect, the foil removing portion is formed in a round hole having a diameter of 0.2 mm to 2.0 mm, or in the cable longitudinal direction. The length (hereinafter abbreviated as the length in the cable longitudinal direction) is a polygonal hole with a width of 0.2 mm to 10 mm, and these foil removal parts are arranged in an arbitrary arrangement, so that the characteristic impedance is more preferably matched to the target value. Can be made.
The reason why the diameter of the round hole is limited to 0.2 mm to 2.0 mm is that if the diameter is less than 0.2 mm, the diameter of the round hole is too small and the foil removal processing by etching becomes difficult. If the diameter exceeds 2.0 mm, the diameter of the round hole becomes too large compared to the width of the signal line, and the characteristic impedance values are uniformly matched to the plurality of signal lines forming the flat cable. This is not preferable because it becomes difficult. The length of the cable in the longitudinal direction of the polygonal hole is limited to 0.2 mm to 10 mm. If the length in the longitudinal direction is less than 0.2 mm, the length of the polygonal hole in the longitudinal direction becomes too small, and the foil is removed by etching. It is not preferable because the processing becomes difficult, and the foil covering part needs to have the same length in the longitudinal direction for controlling the characteristic impedance. Therefore, if the length of the polygonal hole in the cable longitudinal direction exceeds 10 mm, one piece In this signal line, variation in characteristic impedance between the foil removing portion and the foil covering portion in the longitudinal direction becomes large, which is not preferable.

According to a third aspect of the present invention, the arbitrary arrangement is based on a series arrangement in which the foil removing portions are arranged in a line at equal pitch intervals, and the basic units are arranged in a plurality of rows in parallel. Characteristic impedance characterized in that the basic unit of the (n + 1) th column is a repetitive pattern arrangement in which a predetermined value is shifted in the arrangement direction with respect to the basic unit of the column (where n is 1 or more) This is a shielded flat cable that can be matched.
In the shielded flat cable according to the third aspect, in addition to the functions and effects of the shielded flat cable according to the first or second aspect, a plurality of wires are provided by arranging the foil removing portions in the repeated pattern arrangement as described above. It can be adjusted so that the metal foil of the shield layer has a uniform covering area for any one of the signal lines, and the characteristic impedance can be more preferably matched to the target value.

According to a fourth aspect of the present invention, the foil removing section is a plurality of parallel lines that are parallel to the signal line array and have the same pitch, and the metal foil body provided with the foil removing section is left. A plurality of parallel linear metal foil pieces (hereinafter abbreviated as linear metal foil piece arrays) which are shield layers are partially overlapped or not overlapped at all at the facing signal line arrays, It is a shielded flat cable capable of matching characteristic impedance, characterized by having a uniform relationship.
It will be described with reference to FIG. 5 that the linear metal foil piece row has a uniform relationship with the signal wire row facing. FIG. 5 is a schematic cross-sectional view showing an example of a state in which the linear metal foil strips of the shield layer partially overlap the facing signal line rows.
As shown in FIG. 5, the signal line (2) row and the linear metal foil piece (m) row formed on both surfaces of the insulating film (1) of the base material are parallel to each other, so that they face the signal line row. Since the overlapping part (n) with the linear metal foil piece row has the same relation in the longitudinal direction of one signal line and the pitch is the same, all the signal lines have the same relation, so the characteristic impedance Can be matched.
In addition, if the linear metal foil piece (m) row does not overlap at all with the facing signal line (2) row, there is a shield portion made of the linear metal foil piece at a certain distance from the signal line. Therefore, similarly to the above, it has a uniform relationship and can match the characteristic impedance.
When the linear metal foil strips (m) all overlap with the facing signal line (2) rows, each signal line is entirely covered with the metal foil strip, so the shield layer The characteristic impedance is almost the same as when the entire surface is a metal foil.
In the shielded flat cable of the fourth aspect, in addition to the action and effect of the shielded flat cable of the first aspect, the linear metal foil piece array has a uniform relationship with the signal line array, Preferably, the characteristic impedance can be matched to a target value.

  In the shielded flat cable of the present invention, the characteristic impedance is set to a target value due to the fact that the covering area of the metal foil on the shield layer forming surface facing the signal line array formed on one side of the insulating film of the base material is reduced. Can be matched. For example, the foil removal portion of the shield layer may be a round hole, and the size, quantity, and arrangement may be selected as appropriate, and the arrangement may be preferably a repeated pattern arrangement. Therefore, it is not necessary to match the characteristic impedance by thickening the insulation film constituting the shielded flat cable so as to impair the flexibility of the cable, and the characteristic impedance can be matched while maintaining the advantage of the flat cable of flexibility. It becomes like this. The shielded flat cable of the present invention has simple connectivity, good conductor width accuracy and pitch accuracy, and does not require many steps and a great deal of time for manufacturing the shielded flat cable. Therefore, the present invention has a great effect of contributing to the industry.

Hereinafter, the contents of the present invention will be described in more detail with reference to embodiments shown in the drawings. Note that the present invention is not limited thereby.
FIG. 1 is a schematic diagram showing an example of a shielded flat cable according to the present invention. FIG. 1 (a) is a top view, FIG. 1 (b) is a bottom view, and FIG. 1 (c) is c in FIG. It is sectional drawing of -c part. FIG. 2 is a plan view for explaining a shield layer having a repeated pattern arrangement in which the foil removing portion has round holes. FIG. 3 is a plan view for explaining a shield layer having a repeated pattern arrangement in which the foil removing portion has a rectangular hole. FIG. 4 is a plan view for explaining a shield layer in which the foil removing portions are linear in parallel. FIG. 5 is a schematic cross-sectional view showing an example of a state in which the linear metal foil strips of the shield layer partially overlap the facing signal wire rows.
In these figures, 1 is an insulating film (PET film) of a substrate, 2 is a signal line (linear metal foil piece), 2a and 3a are metal foil (copper foil), and 3 is a shield layer (foil removal portion is provided) 4a, 4b are insulating films, 10 is a shielded flat cable capable of matching characteristic impedance, c is a cutting portion, and h is a foil removing portion (metal foil body). (Arbitrary shape), h1 is a round hole (round hole), h2 is a polygonal hole (rectangular hole), h3 is a linear foil removal part, j is a cable longitudinal direction, k is a series unit hole arrangement, m is Linear metal foil pieces, n is an overlapping part (covering part), s is a double-sided metal foil insulating film (double-sided copper foil PET film), t is a connection terminal part (linear metal foil piece exposed part), and z is a series hole It is the residual metal foil part (residual copper foil part) between arrangement | sequences.

1st Embodiment (Example 1) of the shielded flat cable of this invention is demonstrated using FIG. 1, FIG.
A PET film having a width of 16.5 mm, a length of 310 mm, and a thickness of 75 μm was used as the insulating film (1) of the base material, and a thickness of 30 μm as a metal foil (2a) was formed on the entire surface of one side (signal line forming surface) of this PET film. A copper foil having a thickness of 10 μm is adhered as a metal foil (3a) to the entire other surface (shield layer forming surface), and a double-sided metal foil insulating film having a total thickness of 105 μm (double-sided copper foil PET) Film (s) (however, in FIG. 1 (c), the metal foils on both sides are etched).
Next, the metal foil (2a) on the signal line forming surface is removed in parallel with an etching process, the width is 0.3 mm, and the cable foil is parallel to the cable longitudinal direction (j) at a pitch of 0.5 mm. 30 signal line (2) columns were formed (only five signal lines are shown in FIG. 1).
Next, with respect to the copper foil (3a) on the shield layer forming surface, as shown in FIG. 2, a shape that is partially removed in an arbitrary shape by etching is made into a large number of round holes (h1) having a diameter of about 1.0 mm. Etching is performed to provide a foil removal portion (h), and the foil removal portions (h) are arranged in a line at regular pitch (e.g., 2.01.5 mm) intervals as a basic unit. Further, when the basic units are arranged in a plurality of rows in parallel, the basics of the second row similar to the first row are shifted in the hole arrangement direction by 1/5 pitch with respect to the hole pitch of the basic unit of the first row. Units are arranged, and the basic unit in the (n + 1) th column is predetermined with respect to the basic unit in the nth column, such that the basic unit in the third column is shifted by 1/5 pitch with respect to the basic unit in the second column. Repeated pattern arrangement that shifts the value of Forming metal foil and the shield layer sequence (3). In addition, the direction of the serial hole arrangement (k) of the basic unit and the cable longitudinal direction (j) are orthogonal to each other.
Next, with respect to the signal line (2) row and the shield layer (3) surface, a width as an insulating film (4a, 4b) is provided so that a connection terminal portion (t, t) having a length of 5 mm is provided at each end. A shielded flat cable (10) capable of matching the characteristic impedance was manufactured by heat laminating a polyester film with a heat-fusible adhesive layer of 17 mm × length 300 m × thickness 60 μm.
In addition, when mass-producing and manufacturing shielded flat cables, although not shown in particular,
First, for example, a metal foil is continuously bonded to both surfaces of a base insulating film having a width of 500 mm and continuous in the length direction to form a double-sided metal foil insulating film.
Next, on both metal foil surfaces of the double-sided metal foil insulation film, a shield layer is formed by leaving a metal foil body in which the signal line array and the foil removal part are repeatedly arranged in pattern by etching treatment, and etching treatment double-sided metal foil insulation A film.
Next, a predetermined width and length, for example, an insulating film with a heat-fusible adhesive layer cut into a width of 500 mm × a length of 300 mm is formed on the signal line array surface and the shield layer surface of the double-sided metal foil insulating film. Then, heat laminating is performed at the location, and then slitting is performed so that the number of signal lines of the shielded flat cable of the product is, for example, 30, to obtain a flat cable body.
Next, a shield flat cable is manufactured by cutting the end of the flat cable body at a predetermined position, for example, a position of 5 mm, from the front end of the insulating film.

A second embodiment (Example 2) of the shielded flat cable of the present invention will be described with reference to FIGS.
Using the same double-sided copper foil PET film (s) as in Example 1 above, the metal foil (2a) on the signal line forming surface is removed in parallel by etching, and the width is 0.2 mm, Thirty signal line (2) rows arranged in parallel at a pitch of 0.5 mm with respect to the cable longitudinal direction (j) were formed.
Next, as shown in FIG. 3, an etching process is performed on the copper foil (3a) on the shield layer forming surface, as shown in FIG. Are arranged in a line at regular pitch (for example, 4.0 mm) intervals as a basic unit, and when arranging these basic units in a plurality of rows in parallel, the first row in the hole arrangement direction The basic unit of the second row similar to the first row is arranged by shifting by 0.2 mm with respect to the hole pitch of the basic unit, and the basic unit of the third row is shifted by 0.2 mm with respect to the basic unit of the second row. As described above, a repetitive pattern arrangement is performed in which the basic unit in the (n + 1) th column is shifted by a predetermined value with respect to the basic unit in the nth column, and the shield layer (3) of the metal foil body in which the foil removing unit is repeatedly arranged in the pattern arrangement Formed. In addition, the width | variety of the residual metal foil part (residual copper foil part) (z) between the serial hole arrangement | sequences of a basic unit was 0.2 mm. Further, the direction of the series unit hole arrangement (k) and the cable longitudinal direction (j) are orthogonal to each other.
Next, although not particularly shown, the characteristic impedance of the signal line (2) row surface and the shield layer (3) surface is thermally laminated with the insulating films (4a, 4b) in the same manner as in the first embodiment. A shielded flat cable capable of matching was manufactured.

A third embodiment (Example 3) of the shielded flat cable of the present invention will be described with reference to FIGS.
The same double-sided copper foil PET film (s) as in Example 1 was used, and the metal foil (2a) on the signal line forming surface was removed in parallel lines by etching treatment in the same manner as in Example 2. 30 signal line (2) rows having a width of 0.2 mm and arranged in parallel at a pitch of 0.5 mm with respect to the cable longitudinal direction (j) were formed.
Next, with respect to the copper foil (3a) on the shield layer forming surface, as shown in FIG. 4, 31 wires (only 7 in FIG. 4) are parallel to the signal line (2) row and have the same pitch. The linear foil removal part (h3) is provided by removing the parallel line of (shown), 0.3 mm wide parallel to the signal line (2) row, and the pitch is 0.5 mm. 30 shielded metal foils (m) (only 6 are shown in FIG. 4) were left to form a shield layer (3).
Next, although not particularly illustrated, matching of characteristic impedance is performed by thermally laminating insulating films (4a, 4b) on the signal line (2) row surface and the shield layer (3) surface in the same manner as in Example 1. Manufactured a shielded flat cable capable of

  The shielded flat cable of the present invention obtained by the above Examples 1 to 3 had good conductor width accuracy and pitch accuracy without losing the advantages of the flat cable such as flexibility and simple connectivity.

(Comparative Example 1)
Although not particularly illustrated, the description will be given with reference to the conventional flat cable (50) of FIG.
Two insulating films having a width of 15.5 mm × length of 300 mm × thickness of 60 μm each having a heat-fusible adhesive layer on one side, with the adhesive layer surfaces facing each other and 30 widths of 0.2 mm × length A flat cable body is formed by arranging 310 mm × 35 μm-thick rectangular conductors in parallel at a pitch of 0.5 mm, exposing the conductors at both ends 5 mm long, and providing connection terminal portions (terminal conductor exposed portions). It was.
Next, an aluminum PET film with a heat-sealing conductive adhesive having a width of 15.5 mm × a length of 300 mm, an aluminum thickness of 1 μm, a PET thickness of 12 μm, and an adhesive thickness of 40 μm was applied to the aluminum foil surface. The shielded flat cable was manufactured by heat-sealing to the insulating film surface above the flat cable body with a hot roll at 140 ° C. without performing metal foil removal treatment such as etching.

(Comparative Example 2)
Although not shown in particular, a flat conductor having a width of 0.3 mm × length of 310 mm × thickness of 35 μm is used, and as an insulating film, a width of 15.5 mm × length of 300 mm × having a heat-fusible adhesive layer on one side is used. A shielded flat cable was manufactured in the same manner as in Comparative Example 1 except that two insulating films having a thickness of 75 μm were used.

―Measurement of characteristic impedance―
For the shielded flat cables obtained in Examples 1 to 3 and Comparative Examples 1 and 2, using a TDR measuring device, the shield layer is dropped to the ground, and the signal line train is G (ground line) -S (signal line). As a result of measuring the characteristic impedance as -S-G, the characteristic impedances of the shielded flat cables of Examples 1, 2, and 3 were all matched with the target value at about 100Ω. On the other hand, the characteristic impedances of the shielded flat cables of Comparative Examples 1 and 2 were 81Ω and 84Ω, respectively, and were not matched with the intended values.

  The shielded flat cable of the present invention is suitable for use as a high-speed transmission cable because the characteristic impedance can be matched to a target value by reducing the coating area of the metal foil of the shield layer facing the signal line row. Therefore, it can be used for liquid crystal, flat TV image interfaces, internal wiring materials, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic which shows an example of the shield flat cable of this invention, The figure (a) is a top view, The figure (b) is a bottom view, The figure (c) is the cc part of the figure (a). It is sectional drawing. It is a top view for demonstrating the shield layer of a repeating pattern-like arrangement | sequence where a foil removal part is a round hole. It is a top view for demonstrating the shield layer of a repeating pattern shape arrangement | sequence where a foil removal part is a rectangular hole. It is a top view for demonstrating the shield layer whose foil removal part is a linear form parallel. It is a schematic cross-sectional view showing an example of a state in which a linear metal foil piece row of a shield layer partially overlaps a facing signal line row. It is a perspective view which shows an example of the conventional flat cable.

Explanation of symbols

1 Base insulating film (PET film)
2 signal lines (linear metal foil pieces)
2a, 3a Metal foil (copper foil)
3 Shield layer (metal foil body provided with a foil removing portion) (metal foil body having a repeated pattern arrangement of the foil removing portion)
4a, 4b Insulating film 10 Shield flat cable capable of matching characteristic impedance c Cutting part h Foil removing part (arbitrary shape)
h1 Round hole (round hole)
h2 Polygonal hole (rectangular hole)
h3 Linear foil stripping part j Cable longitudinal direction k Basic unit serial hole arrangement m Linear metal foil pieces n Overlapping part (covering part)
s Double-sided metal foil insulation film (double-sided copper foil PET film)
t Connection terminal part (exposed part of linear metal foil)
z Residual metal foil between the series of holes (residual copper foil)

Claims (4)

By removing the metal foil on one side (signal line forming surface) of the metal foil formed on both surfaces of the insulating film of the base material into a plurality of parallel lines by etching, a plurality of parallel linear metal foils The signal lines are formed by leaving the pieces, and the metal foil on the other side (shield layer forming surface) is partially removed in an arbitrary shape by etching to leave the metal foil body provided with the foil removing portion. The shield flexible flat is formed by forming a shield layer, and covering the signal line row surface with an insulating film leaving the terminal exposed portion, and leaving the terminal layer exposed portion or covering the entire surface with the insulating film. A cable,
A shielded flexible flat cable capable of matching a characteristic impedance, characterized in that the characteristic impedance is matched to a target value because a covering area of the metal foil of the shield layer facing the signal line row is reduced.   The foil removing portion is a round hole having a diameter (maximum diameter) of 0.2 mm to 2.0 mm, or a polygonal hole having a length with respect to the cable longitudinal direction of 0.2 mm to 10 mm. 2. The shielded flexible flat cable capable of matching characteristic impedance according to claim 1, wherein the shielded flexible flat cable is aligned in an arbitrary arrangement.   The arbitrary arrangement is based on a series arrangement in which the foil removing portions are arranged in a line at equal pitch intervals, and a plurality of the basic units are arranged in parallel. The n-th column (where n is 1 or more) 3. The characteristic impedance matching according to claim 1, wherein the basic unit in the (n + 1) -th column is a repetitive pattern array in which the basic unit is shifted by a predetermined value in the array direction. Shielded flexible flat cable. The foil removing portion is a plurality of parallel lines that are parallel to the signal line array and have the same pitch, and a plurality of parallel that are shield layers in which the metal foil body provided with the foil removing portion is left. 2. The characteristic impedance matching according to claim 1, wherein said linear metal foil piece has a uniform relationship by partially overlapping or not overlapping at all to the signal line array facing each other. Shielded flat cable.