JP2003036733A - Flexible flat cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible flat cable which can have contacting points to connectors formed on its one surface and remove the cause of interfering factors to impedance, while improving shielding capacity. SOLUTION: The flexible flat cable is a flexible insulator sheet 2, one side of which is installed with the primary conductive pattern P1 and the other side of which with the secondary conductive pattern P2. The primary conductive pattern P1 comprises a plurality of patterns 3's, each containing a signal pattern S and two ground patterns G's placed on both sides of S, which are extended along the lengthwise direction of the flexible flat cable 2. The secondary conductive pattern P2 comprises a plurality of conductive patterns 5's which are extended along the lengthwise direction of the insulating sheet 2. Each conductive pattern 5 is arranged in a position facing each pattern group 3 sandwiching the insulating sheet 2 between.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat flexible cable having an electromagnetic shield function, and more particularly to a technique that takes into consideration the relationship between the arrangement of signal patterns and ground patterns and connector contacts.

[0002]

2. Description of the Related Art Conventionally, on one surface of a flexible insulating sheet,
A flat flexible cable is known in which a plurality of signal patterns are provided along the longitudinal direction of an insulating sheet and a ground means for electromagnetic shielding is provided on the other surface.

The grounding means provided on the other surface of the insulating sheet may be composed of a metal layer covering the entire other surface of the insulating sheet, or may be composed of a metal net to enhance flexibility. The technique of providing the metal layer is described in, for example, Japanese Utility Model Laid-Open No. 62-5417 (publication 1). A technique using a metal net is disclosed in, for example, Japanese Patent Laid-Open No. Hei 10
No. 112224 (publication 2).

In recent years, miniaturization of various electronic devices,
Along with higher performance, higher density is required. Therefore, the signal cable itself is required to have a high wiring density. When the arrangement pitch of the signal patterns is made small in order to obtain a high wiring density, there is a problem that the impedance deteriorates and crosstalk becomes large. The above-mentioned publication 1 describes a technique in consideration of this point.

That is, this publication 1 describes a technique in which signal patterns and ground patterns are alternately arranged in a zigzag pattern on both surfaces of an insulating sheet. Both end portions of each ground pattern are arranged on the same plane as or overlapping with the end portions of the ground patterns which are diagonally opposed to each other via an insulating sheet.

[0006]

By the way, in such a signal cable having a high density signal pattern, a connector is often used for connection to a device or for connection between cables. This is because the use of the connector can facilitate connection and improve reliability. In that case, the number of contacts corresponding to the number of signal patterns is provided at each end of the signal cable. These contacts are contacts having a function of contacts for electrically connecting with the connector.

In the signal cable described in the above publication 1, since the signal pattern is provided on both sides of the insulating sheet, it is necessary to provide the contacts for the connector on both sides of the insulating sheet. Therefore, there is a problem that the manufacturability of the cable is lowered. Manufacturability also affects the connector. For example, it becomes impossible to use a single-sided contact type connector in which a contact is provided only on the upper surface.

Further, in the above-mentioned publication 1, a signal pattern and a ground pattern are alternately provided on one surface of an insulating sheet,
A technique in which a ground pattern is provided on the entire other surface is also disclosed. However, in this case, a means for electrically connecting the ground pattern on one surface to the ground pattern on the other surface is required. Usually, a structure is provided in which through holes are provided on the front and back of the insulating sheet, and conductors are patterned therein to electrically connect the ground patterns. As a result, this patterned portion causes disturbance of impedance. Specifically, Via
Examples include changing the pitch of holes and pads.

An object of the present invention is to provide a flat type flexible cable in which contacts to a connector can be formed on one surface of a cable, an element causing disturbance of impedance is eliminated, and shield performance can be improved. To do.

[0010]

DISCLOSURE OF THE INVENTION The present invention is a flat type flexible cable having a first conductor pattern provided on one surface of a flexible insulating sheet and a second conductor pattern provided on the other surface thereof. The first conductor pattern includes a plurality of pattern groups each including one signal pattern extending in a length direction of the insulating sheet and two ground patterns arranged on both sides of the signal pattern. The conductor pattern includes a plurality of conductor patterns that extend in the length direction of the insulating sheet and do not conduct electricity, and each conductor pattern is arranged at a position corresponding to each pattern group through the insulating sheet. It has a structure.

According to the present invention, the signal pattern is provided only on one surface, the conductor pattern provided on the other surface is insulated by the insulating sheet, and electricity is not applied. As a result, the contact point for the connector can be formed on one surface of the cable, and it is possible to eliminate an element (such as a pitch change of a via hole or a pad portion) that causes impedance disturbance. Further, by disposing the ground patterns on both sides of the signal pattern and arranging the conductor patterns on the other surface side as well to surround the signal pattern, the shield performance can be improved.

In the present invention, it is preferable to adopt a structure in which the ground pattern provided on one surface of the insulating sheet and the conductor pattern provided on the other surface are insulated by the insulating sheet. With this configuration, it is possible to form a so-called floating metal structure in which the conductor pattern is not electrically connected to the ground pattern. This conductor pattern exerts an effect of strengthening coupling with a pattern group composed of one signal pattern and two ground patterns on both sides thereof.

The width dimension of the conductor pattern is preferably set larger than the maximum width of one pattern group. Thereby, the coupling action of the conductor pattern with the pattern group can be further enhanced.

In the present invention, it is desirable to set the interval α between the signal pattern and the ground pattern and the interval β between the ground patterns to be equal to each other from the viewpoint of eliminating the disturbance of the impedance and exhibiting the uniform shield performance. Furthermore, it is desirable to set the width dimensions of the signal pattern and the ground pattern to be substantially equal.

The conductor patterns are arranged at intervals γ in the width direction of the insulating sheet, and among the conductor patterns,
It is desirable that the interval γ between the adjacent conductor patterns is smaller than both the interval α between the signal pattern and the ground pattern and the interval β between the ground patterns of the adjacent pattern groups. With this setting, it is possible to effectively prevent crosstalk by separating the conductor patterns from each other while strengthening the coupling by the conductor patterns.

In each of the pattern groups of the first conductor pattern, a space γ between the conductor patterns is provided at a position corresponding to a space β between the ground patterns of the adjacent pattern groups.
It is desirable that the arrangement position of is set. With this setting, the crosstalk prevention function can be further enhanced.

In the present invention, it is possible to adopt a structure in which a coating layer made of a flexible low dielectric constant insulator is provided on the first conductor pattern. When the coating layer is provided, it is possible to effectively protect both the signal pattern and the ground pattern and prevent abrasion and stains.

Further, an electromagnetic shield layer may be provided on the coating layer. When the electromagnetic shield layer is provided in this way, the shield effect can be further enhanced.

A flexible second insulating sheet is provided on the first conductor pattern, and the flexible second insulating sheet extends on the second insulating sheet in the length direction of the second insulating sheet and does not conduct electricity.
A conductor pattern may be formed, and the third conductor pattern may be arranged at a position corresponding to the second conductor pattern.

As described above, the entire signal pattern is surrounded by the ground patterns arranged on both sides of the signal pattern, the conductor pattern provided on the insulating sheet, and the conductor pattern provided on the second insulating sheet. In this case, the shield performance of this cable can be further improved.

It is desirable that the insulating sheet and the second insulating sheet are made of the same material, and the second conductor pattern and the third conductor pattern are made of the same material. This is because the shielding function can be made more uniform by using the same material for the insulating sheets and the conductor patterns for exhibiting the same function.

Further, it is desirable that an electromagnetic shield layer covering the surface of the cable is formed on each of the second conductor pattern and the third conductor pattern. With this configuration, the shield function of the cable can be further enhanced, and the electromagnetic shield layer exhibits the function of protecting the cable.

In the flat type flexible cable according to the present invention, the first conductor pattern is provided on one surface of the flexible insulating sheet, and the second conductor pattern is provided on the other surface thereof. A plurality of pattern groups each including one signal pattern and one ground pattern extending in the length direction of the second conductive pattern, the second conductor pattern extending in the length direction of the insulating sheet It is possible to adopt a configuration in which each conductor pattern is arranged at a position corresponding to each pattern group via an insulating sheet.

Even with this structure, the contact point for the connector can be formed on one surface of the cable, and the elements that cause the impedance to be disturbed (via holes, pitch change of the pad portion, etc.) can be eliminated. Further, by disposing the ground patterns on both sides of the signal pattern and arranging the conductor patterns on the other surface side as well to surround the signal pattern, the shield performance can be improved.

Here, it is desirable that the ground pattern and the conductor pattern are insulated by an insulating sheet. Further, the width dimension of the conductor pattern is preferably set larger than the maximum width of the pattern group. In addition, the conductor patterns forming the second conductor pattern are arranged at intervals γ in the width direction of the insulating sheet, and the interval γ between adjacent conductor patterns in each conductor pattern is
It is desirable to be smaller than both the interval α between the signal pattern and the ground pattern and the interval β between the adjacent pattern groups. Further, it is preferable that, in each pattern group of the first conductor pattern, the arrangement position of the interval γ between the conductor patterns is set at a position corresponding to the region of the interval β between the adjacent pattern groups.

It is also possible to employ a structure in which a coating layer made of a flexible low dielectric constant insulator is provided on the first conductor pattern, and an electromagnetic shield layer is provided on the coating layer. it can.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on the embodiments shown in the drawings. FIG. 1 is a perspective view in which the present invention is applied to a single-ended 3-coplanar type flexible flat cable (FFC). FIG. 2 is a model diagram showing a cross section of the cable.

This flexible flat cable (hereinafter, simply referred to as a cable) 1 has a flexible insulating sheet 2 made of an insulating resin or the like on which one surface (front surface) is formed.
The conductor pattern P1 is provided, and the second surface is formed on the other surface (back surface).
This is a configuration in which the conductor pattern P2 is provided.

The first conductor pattern P1 is a pattern group including one signal pattern S extending in the length direction of the insulating sheet 2 and two ground patterns G, G arranged on both sides of the signal pattern S. 3 sets are provided.
FIG. 1 shows an example in which four sets are provided. The number of sets can be increased or decreased as needed. The minimum unit is two sets, and there may be five or more sets.

The second conductor pattern P2 includes a plurality of conductor patterns 5 extending in the length direction of the insulating sheet 2.
FIG. 1 shows an example including four conductor patterns.
Each conductor pattern 5 is arranged at a position corresponding to each pattern group 3 via the insulating sheet 2.

The signal pattern S, the ground pattern G, and the conductor pattern 5 are made of a metal material having excellent conductivity such as silver or copper. These patterns can be formed by using existing techniques such as a method of bonding wires together and a method of utilizing etching technology.

As described above, the signal pattern S is provided on only one surface, the conductor pattern 5 provided on the other surface is insulated by the insulating sheet 2, and no electric current flows through the conductor pattern 5. . Therefore, a contact point for the contact portion 101A of the terminal 101 of the connector 100 shown in FIG. 12 can be formed on one surface of the cable, and an element that causes impedance disturbance (change in pitch of via hole or pad portion) can be eliminated. . The contact portion 101A of the terminal 101 is located at two positions, upper and lower, but it may be in electrical contact with either. Further, the ground pattern G is arranged on both sides of the signal pattern S, and the conductor pattern 5 is also arranged on the other surface side to surround the signal pattern S, so that the shield performance can be improved.

In this embodiment, the ground pattern G provided on one surface of the insulating sheet 2 and the conductor pattern 5 provided on the other surface are insulated by the insulating sheet 2. That is, each conductor pattern 5 has a so-called floating metal structure that is not electrically connected to the ground pattern G. This conductor pattern 5 is
It is provided in order to exert the action of strengthening the coupling with one signal pattern S and the pattern groups 3 composed of the two ground patterns G on both sides thereof.

The width dimension d2 of each conductor pattern 5 is set larger than the maximum width d1 of one pattern group 3.
This is to further strengthen the coupling action of the conductor pattern 5 with the pattern group 3.

Further, the interval α between the signal pattern S and the ground pattern G and the interval β between the ground patterns G are both set to the same interval. Furthermore, the signal pattern S
And the width dimension of the ground pattern G are set to be substantially equal. With this configuration, it is considered that the disturbance of impedance is eliminated and more uniform shield performance can be exhibited.

The conductor patterns 5 are arranged at intervals γ in the width direction of the insulating sheet 2. Then, in each conductor pattern 5, the interval γ between the adjacent conductor patterns 5 and 5 is smaller than any of the interval α between the signal pattern S and the ground pattern G and the interval β between the adjacent ground patterns G and G. It is set. The reason for setting in this way is to prevent the crosstalk by separating the conductor patterns 5 from each other while strengthening the coupling by the conductor patterns 5.

In each pattern group 3, the ground patterns G of the adjacent pattern groups 3 and 3 and the space β between the G patterns
In the position corresponding to the area of, the arrangement position of the interval γ between the conductor patterns 5 and 5 is set. This is intended to further enhance the crosstalk prevention function. There is no signal pattern S between the ground patterns G and G. Therefore, even if the interval γ portion, which is the gap between the conductor patterns, is arranged in this region, the shield effect for the signal pattern S is not significantly affected.

FIG. 3 shows the impedance (Ω) on the Y axis,
Insulator (insulating sheet 2) with conductor width (mm) on X axis
3 is a graph showing the relationship between impedance and shape parameter when the relative dielectric constant of εr = 2.5 and when εr = 4.3. Here, the data is shown when the thickness of the insulator (insulating sheet 2) is 30 μm, and the interval α between the signal pattern S and the ground pattern G and the interval β between the ground patterns G are 1 mm pitch. There is.

From FIG. 3, the larger the conductor width,
It can be confirmed that the impedance drops. Also, under the same conditions, it can be confirmed that the impedance decreases as the relative permittivity εr increases.

FIG. 4 shows impedance (Ω) on the Y axis,
6 is a graph showing the relationship between impedance and shape parameter when the insulator thickness (μ) is taken on the X axis and the relative permittivity of the insulator (insulating sheet 2) is εr = 4.3.
From this FIG. 4, it can be confirmed that the impedance increases as the insulator thickness increases.

FIG. 5 shows the result of a three-coplanar electromagnetic field analysis when an electric signal is applied to the signal pattern S in the pattern group 3. In this embodiment, the advantage that the cable 1 can be made thin is obtained. Further, the manufacturability is good and it can be provided at a low cost.

(Embodiment 2) In FIG. 6, a coating layer 6 made of a flexible low dielectric constant insulator is provided on the first conductor pattern P1, and an electromagnetic shield layer is further provided on the coating layer 6. 7 shows an example in which 7 is provided. Here, the top of the first conductor pattern P1 is the surface opposite to the surface of the first conductor pattern P1 in contact with the insulating sheet 2 in FIG. The top of the coating layer 6 means that the coating layer 6 is the first conductor pattern P.
It is on the surface opposite to the surface in contact with 1. In this case, the coating layer 6 has a structure in which flexible sheets are laminated from above. The electromagnetic shield layer 7 can be formed by applying a metal plating film to the surface of the coating layer 6, for example. Alternatively, a sheet material having a film made of a magnetic material, for example, Maxell tape or amorphous tape, may be attached to one or both surfaces of the cable 1 having the electromagnetic shield layer 7. When the sheet material is provided on the second conductor pattern P2, the conductor pattern 5 can be protected.

The coating layer 6 and the electromagnetic shield layer 7 are
Can be provided in a separate step. Further, it is also possible to use a sheet material in which the coating layer 6 and the electromagnetic shield layer 7 are integrally provided and to stick the sheet material.

When the coating layer 6 is provided in this manner, both the signal pattern S and the ground pattern G can be effectively protected so as not to be worn or soiled. Also,
By providing the electromagnetic shield layer 7 on the coating layer 6, the shield effect can be further enhanced.

FIG. 7 is a diagram showing an electromagnetic field analysis result of a three coplanar shield type including the electromagnetic shield layer 7. From this FIG. 7, it can be confirmed that the electromagnetic shield action is effectively exhibited by the existence of the electromagnetic shield layer 7.

In the second embodiment, compared with the first embodiment, the noise resistance performance can be improved, but the cable 1 is thicker by the amount of the coating layer 6 and the electromagnetic shield layer 7.

(Third Embodiment) FIG. 8 shows an embodiment in which the present invention is applied to a cable 10 of a single-ended two-coplanar type. That is, in this cable 10, the first conductor pattern P1 is provided on one surface of the flexible insulating sheet 2, and the second conductor pattern P1 is provided on the other surface.
Two are provided. The first conductor pattern P1 includes a plurality of pattern groups 30 each including one signal pattern S and one ground pattern G extending in the length direction of the insulating sheet 2.

The second conductor pattern P2 includes a plurality of conductor patterns 50 extending in the length direction of the insulating sheet 2, and each conductor pattern 50 is located at a position corresponding to each pattern group 30 via the insulating sheet 2. It is arranged.

Ground pattern G and conductor pattern 50
Are insulated by the insulating sheet 2. The width dimension d4 of the conductor pattern 50 is set larger than the maximum width d3 of the pattern group 30. Interval α between the signal pattern S and the ground pattern G in the pattern group 30
Is set to be smaller than the interval β between the adjacent pattern groups 30.

Further, the conductor patterns 50 are arranged at intervals γ in the width direction of the insulating sheet 2, and among the conductor patterns 50, the interval γ between adjacent conductor patterns 50.
Is set to be smaller than both the interval α between the signal pattern S and the ground pattern G in the pattern group 30 and the interval β between the adjacent pattern groups 50. further,
In each pattern group 30, the arrangement position of the interval γ between the conductor patterns 50 is set at a position corresponding to the region of the interval β between the adjacent pattern groups 30.

Also in this embodiment, the contact point for the connector can be formed on one surface of the cable, and the elements that cause the impedance to be disturbed (via hole, change in the pitch of the pad portion, etc.) can be eliminated. Further, the ground pattern G is arranged on both sides of the signal pattern S, and the conductor pattern 50 is also arranged on the other surface side so as to surround the signal pattern S, so that the shield performance can be improved.

In the cable 10 of this embodiment, the number of signal patterns S can be increased and the density can be substantially increased, as compared with the cable 1 of the single-ended three-coplanar type in Embodiment 1, but The noise resistance performance deteriorates. That is, as can be confirmed from the coplanar electromagnetic field analysis result shown in FIG. 9, the electromagnetic shield effect is slightly reduced.

(Embodiment 4) In FIG. 10, a coating layer 6 made of a flexible low dielectric constant insulator is provided on the first conductor pattern P1, and an electromagnetic shield layer is further provided on the coating layer 6. 7 shows an example in which 7 is provided. Here, the top of the first conductor pattern P1 is the surface opposite to the surface of the first conductor pattern P1 in contact with the insulating sheet 2 in FIG. The top of the coating layer 6 is the surface opposite to the surface of the coating layer 6 in contact with the first conductor pattern P1. In this case, the coating layer 6 has a structure in which flexible sheets are laminated from above. The electromagnetic shield layer 7 can be formed by applying a metal plating film to the surface of the coating layer 6, for example. Further, a sheet material having a film made of a magnetic material, such as a Maxell tape or an amorphous tape, may be laminated on one or both surfaces of the cable 1.

FIG. 11 is a diagram showing an electromagnetic field analysis result of a single-ended two-coplanar shield type including the electromagnetic shield layer 7. From this FIG. 11, it can be confirmed that the electromagnetic shield action is effectively exhibited by the existence of the electromagnetic shield layer 7.

In comparison with the third embodiment, the fourth embodiment has a characteristic that the noise resistance performance is good, but
The coating layer 6 and the electromagnetic shield layer 7 become thicker as much as they exist.

(Fifth Embodiment) FIG. 13 shows the first embodiment.
An example is shown in which an insulating sheet and a conductor pattern are further added to the single-ended 3-coplanar type flexible flat cable shown in.

In this embodiment, the first conductor pattern P
1. A flexible second insulating sheet 22 is provided on the first
A third conductor pattern P3 that extends in the length direction of the second insulating sheet 22 and does not conduct electricity is provided on the insulating sheet 22. The third conductor pattern P3 is the second conductor pattern P2.
It is located at the position corresponding to. Here, the top of the first conductor pattern P1 is the surface opposite to the surface of the first conductor pattern P1 in contact with the insulating sheet 2 in FIG. The insulating sheet 22 is first on the insulating sheet 22.
It is on the surface opposite to the surface in contact with the conductor pattern P1.

The third conductor pattern P3, like the second conductor pattern P2, includes a plurality of conductor patterns 5 that do not conduct electricity.
It is equipped with 5. Each conductor pattern 55 constitutes a so-called floating metal that is not electrically connected to the ground pattern G. Each conductor pattern 5 of the second conductor pattern P2 has a conductor width d2 smaller than that of the conductor pattern 5 shown in FIG. In FIG. 12, the conductor pattern 5 and the conductor pattern 55 have the same width and are arranged at positions facing each other.

Therefore, the interval γ1 between the adjacent conductor patterns 5 and 5 and the interval γ2 between the conductor patterns 55 and 55 are both set to be equal. Conductor patterns 5, 5
The conductor width of 5 is smaller than that of FIG. However, the conductor patterns 5 and 55 are considered to have at least conductor widths reaching the ground patterns G and G on both sides of the signal pattern S, respectively.

Each conductor pattern 5 of the second conductor pattern P2
And the conductor patterns 55 of the third conductor pattern P3 are made of the same material. Further, the second insulating sheet 22 and the insulating sheet 2 are also made of the same material.

Also in the fifth embodiment, the contact to the contact 101A of the connector 100 shown in FIG. 12 can be formed on one surface of the cable, and the element causing the disturbance of the impedance can be eliminated. Furthermore, the entire signal pattern S is composed of the ground patterns G, G arranged on both sides of the signal pattern S, the conductor pattern 5 provided on the insulating sheet 2, and the conductor pattern 55 provided on the second insulating sheet 22. It has a surrounding form. As a result, the shield performance of this cable 1 can be further improved as compared with the cable 1 shown in the first embodiment.

(Sixth Embodiment) FIG. 14 shows a fifth embodiment.
In addition to the single-ended 3 coplanar type flexible flat cable 1 shown in, the electromagnetic shield layer 6
An example in which 1 and 62 are added is shown. Electromagnetic shield layer 6
1 is provided on the second conductor pattern 5, and the electromagnetic shield layer 62 is provided on the third conductor pattern 55.
Here, the upper side of the second conductor pattern 5 is the side opposite to the side where the second conductor pattern 5 is in contact with the insulating sheet 2 in FIG. The top of the third conductor pattern 55 is the surface opposite to the surface of the third conductor pattern 55 in contact with the second insulating sheet 22.

The electromagnetic shield layers 61 and 62 can be formed by applying, for example, a metal plating film to the surfaces of the conductor patterns 5 and 55 and the exposed insulating sheet. However, here, the cable 1 has a structure in which a sheet material having a film made of a magnetic material, for example, a Maxell tape or an amorphous tape is attached to both surfaces of the cable 1. Thus, when the electromagnetic shield layers 61 and 62 are added to both surfaces of the cable 1, the electromagnetic shield effect of the cable can be further enhanced. Further, the electromagnetic shield layers 61, 62
Forms the surface of the cable and thus serves to protect the cable itself.

In the fifth and sixth embodiments, an example in which the present invention is applied to a single-ended three-coplanar type flexible flat cable is shown.
The same can be applied to the coplanar type flexible flat cable as in the fifth and sixth embodiments.

[0065]

As described above, according to the flat type flexible cable of the present invention, the contact to the connector can be formed on one surface of the cable, the element causing the impedance disturbance is eliminated, and the shield performance is also provided. Can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view of a flat flexible cable according to a first embodiment of the present invention.

FIG. 2 is a model diagram showing a cross section of the flat flexible cable according to the first embodiment of the present invention.

FIG. 3 is a graph showing the relationship between the impedance and the shape parameter of the flat flexible cable according to the first embodiment of the present invention.

FIG. 4 is a graph showing the relationship between the impedance and the shape parameter of the flat flexible cable according to the first embodiment of the present invention.

FIG. 5 is a diagram showing an electromagnetic field analysis result according to the first embodiment of the present invention.

FIG. 6 is a model diagram showing a cross section of a flat flexible cable according to a second embodiment of the present invention.

FIG. 7 is a diagram showing an electromagnetic field analysis result of the flat flexible cable according to the second embodiment of the present invention.

FIG. 8 is a model diagram showing a cross section of a flat flexible cable according to a third embodiment of the present invention.

FIG. 9 is a diagram showing an electromagnetic field analysis result of a flat flexible cable according to a third embodiment of the present invention.

FIG. 10 is a model diagram showing a cross section of a flat flexible cable according to a fourth embodiment of the present invention.

FIG. 11 is a diagram showing an electromagnetic field analysis result of the flat flexible cable according to the third embodiment of the present invention.

FIG. 12 is a sectional view of a connector to which a flat flexible cable can be connected.

FIG. 13 is a model diagram showing a cross section of a flat flexible cable according to a fifth embodiment of the present invention.

FIG. 14 is a model diagram showing a cross section of a flat flexible cable according to a sixth embodiment of the present invention.

[Explanation of symbols]

1 cable 2 Insulation sheet 3 patterns 5 conductor pattern 6 coating layer 7 Electromagnetic shield layer 10 cables 22 Second insulation sheet 30 patterns 50 conductor pattern 55 conductor pattern 61 Electromagnetic shield layer 62 Electromagnetic shield layer S signal pattern G ground pattern P1 First conductor pattern P2 Second conductor pattern P3 Third conductor pattern

Claims (23)

[Claims] 1. A flat flexible cable in which a first conductor pattern is provided on one surface of a flexible insulating sheet, and a second conductor pattern is provided on the other surface thereof, wherein the first conductor pattern comprises: A plurality of sets of pattern groups each including one signal pattern extending in the length direction of the insulating sheet and two ground patterns arranged on both sides of the signal pattern are provided, and the second conductor pattern is formed of the insulating sheet. A flat flexible cable, comprising a plurality of conductor patterns that extend in the length direction and do not conduct electricity, and each conductor pattern is arranged at a position corresponding to each pattern group via the insulating sheet. 2. The flat flexible cable according to claim 1, wherein the ground pattern and the conductor pattern are insulated by the insulating sheet. 3. The flat flexible cable according to claim 1, wherein the width dimension of the conductor pattern is set to be larger than the maximum width of one pattern group. 4. The flat flexible cable according to claim 1, wherein an interval α between the signal pattern and the ground pattern and an interval β between adjacent ground patterns are set to be equal to each other. 5. The flat flexible cable according to claim 1, wherein the width dimensions of the signal pattern and the ground pattern are set to be substantially equal to each other. 6. The flat flexible cable according to claim 1, wherein the conductor patterns are arranged at intervals γ in a width direction of the insulating sheet. 7. The distance γ between adjacent conductor patterns in each of the conductor patterns is smaller than both the distance α between the signal pattern and the ground pattern and the distance β between the ground patterns of the adjacent pattern groups. Claim 1
Flat flexible cable described. 8. An arrangement position of an interval γ between the conductor patterns is set at a position corresponding to a region of an interval β between the ground patterns of adjacent pattern groups in each pattern group of the first conductor patterns. The flat flexible cable according to claim 1, wherein 9. A coating layer made of a flexible low dielectric constant insulator is provided on the first conductor pattern.
The flat flexible cable according to any one of claims 1 to 8. 10. The flat flexible cable according to claim 9, wherein an electromagnetic shield layer is provided on the coating layer. 11. The flat flexible cable according to claim 1, wherein the first conductor pattern electrically contacts a terminal of the connector. 12. A flexible second insulating sheet is provided on the first conductor pattern, extends on the second insulating sheet in the length direction of the second insulating sheet, and does not conduct electricity. A conductor pattern is formed, and the third conductor pattern is
The flat flexible cable according to claim 1, wherein the flat flexible cable is arranged at a position corresponding to the second conductor pattern. 13. The flat mold according to claim 12, wherein the insulating sheet and the second insulating sheet are formed of the same material, and the second conductor pattern and the third conductor pattern are formed of the same material. Flexible cable. 14. The flat flexible cable according to claim 12, wherein an electromagnetic shield layer covering a surface of the cable is formed on each of the second conductor pattern and the third conductor pattern. 15. A flat flexible cable in which a first conductor pattern is provided on one surface of a flexible insulating sheet and a second conductor pattern is provided on the other surface thereof, wherein the first conductor pattern is A plurality of pattern groups each including one signal pattern extending in the length direction of the insulating sheet and one ground pattern are provided, and the second conductor pattern extends in the length direction of the insulating sheet and does not conduct electricity. A flat flexible cable, comprising a plurality of conductor patterns, wherein each conductor pattern is arranged at a position corresponding to each pattern group via the insulating sheet. 16. The flat flexible cable according to claim 15, wherein the ground pattern and the conductor pattern are insulated by the insulating sheet. 17. The flat flexible cable according to claim 15, wherein a width dimension of the conductor pattern is set to be larger than a maximum width of the pattern group. 18. The flat flexible cable according to claim 15, wherein the conductor patterns forming the second conductor pattern are arranged at intervals γ in the width direction of the insulating sheet. 19. The interval γ between adjacent conductor patterns in each of the conductor patterns is smaller than both the interval α between the signal pattern and the ground pattern and the interval β between adjacent pattern groups. Flat flexible cable described. 20. An arrangement position of a gap γ between the conductor patterns is set at a position corresponding to a region of a gap β between adjacent pattern groups in each pattern group of the first conductor pattern. Item 18. A flat flexible cable according to Item 15. 21. The flat flexible cable according to claim 15, wherein a coating layer made of a flexible low dielectric constant insulator is provided on the first conductor pattern. 22. The flat flexible cable according to claim 21, wherein an electromagnetic shield layer is provided on the coating layer. 23. The flat flexible cable according to claim 15, wherein the first conductor pattern electrically contacts a terminal of the connector.