JP2002100842A - Flexible flat wiring board and method of adjusting its impedance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible flat wiring board, enabling the internal impedance to be adjusted. SOLUTION: An insulation layer 2 for spacing a plurality of conductor wires 1 from a ground layer 3 uses a laminate of a plurality of insulative films 7a, 7b, etc. This facilities adjusting a spacing size T1, between the conductor wire 1 and the ground layer 3 and hence adjusting the internal impedance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible flat wiring board in which a plurality of conductor wires are juxtaposed between a pair of protective layers, and a method of adjusting the internal impedance of the flexible flat wiring board.
In particular, the present invention relates to a flexible flat wiring board having excellent transmission characteristics and a method for adjusting the internal impedance thereof.

[0002]

2. Description of the Related Art Notebook type personal computers, plasma displays, various measuring instruments, DVDs (Digital Vers.
atile Disc) Player, High Resolution LCD (Liquid Cry)
In the field of wiring of devices that use high-speed digital transmission and analog transmission such as devices, printers, copiers, base station backplanes of mobile phones, multiplex communication devices, digital video links, etc. With the transmission technology, the performance of the cable also needs to be improved.

For example, in a cable for connecting a main body substrate of a personal computer to a screen LCD device or the like, conventionally, an insulating layer is provided around a core wire in consideration of transmission characteristics (that is, characteristics for keeping impedance constant). An ultrafine coaxial cable formed by forming a braid as an intervening earth layer is used.
For example, high-speed transmission interface LVDS (Low Voltag
e Differential Signaling) communication.

However, when a micro coaxial cable is used, it is necessary to connect the micro coaxial cable to a main body substrate, an LCD device, or the like by soldering. If connection is performed at a fine pitch in consideration of connection area efficiency, high soldering accuracy will be required, so connection processing cost is high, and cost reduction, stable supply and stable quality Had become a wall.

In view of this, a method is conceivable in which a flexible flat wiring board is used instead of the micro coaxial cable, and the flexible flat wiring board is connected to a main board of a personal computer or a screen LCD device via a connector of the flexible flat wiring board.

However, in the flexible flat wiring board, forming a ground layer at a constant distance around all the conductor wires in order to keep the impedance constant, greatly increases the thickness of the flexible flat wiring board. Will be. Then, not only is it inconvenient to handle, but also results in impairing the flexibility of the flexible flat wiring board.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a flexible flat wiring board which can obtain a given internal impedance equivalent to that of a conventional micro coaxial cable, and which is thin and has sufficient flexibility. To provide.

[0008]

Means for Solving the Problems In order to solve the above problems,
The invention according to claim 1, wherein a plurality of conductor wires are provided side by side on one surface of the insulating layer, a ground layer is formed on a plane on the other surface of the insulating layer, and the conductor wire and the ground are provided. In the flexible flat wiring board having a protective layer formed on the outer surface of the layer, the insulating layer has a plurality of laminated insulating films.

According to a second aspect of the present invention, there is provided the semiconductor device according to the first aspect, wherein a plurality of conductor lines are arranged in parallel on one surface of the insulating layer, and a ground layer is formed on a plane on the other surface of the insulating layer. And a protective layer is formed on the outer surface of the ground layer, and the conductor wire and the ground layer are connected to a predetermined connector or a predetermined substrate at a longitudinal end thereof. At the end, a predetermined insulating spacer for relatively increasing the thickness of the end of the insulating layer is mounted in the insulating layer, and the width of the conductor wire corresponding to the position where the spacer is mounted The dimension is set to be larger than the width dimension of the conductor wire at another position.

The invention according to claim 3 is the flexible flat wiring board according to claim 2, wherein the insulating layer has a plurality of laminated insulating films.

According to a fourth aspect of the present invention, there is provided the flexible flat wiring board according to the first or third aspect, wherein each of the insulating films has a different thickness and / or a different dielectric constant. Is selected from among the above.

According to a fifth aspect of the present invention, there is provided the flexible flat wiring board according to any one of the second to fourth aspects, wherein at least a part or all of a region in a longitudinal direction including at least a part that is curved. In the region, a reinforcing layer for adjusting the thickness of the outside of the conductor wire is formed so that the conductor wire is located at the center in the thickness direction.

According to a sixth aspect of the present invention, there is provided the semiconductor device according to the first aspect, wherein a plurality of conductor wires are provided in parallel on one surface of the insulating layer, and a ground layer is formed on a plane on the other surface of the insulating layer. And a method for adjusting the internal impedance of a flexible flat wiring board in which a protective layer is formed on the outer surface of the ground layer, wherein the insulating layer is provided at a longitudinal end connected to a predetermined connector or a predetermined substrate. A predetermined insulating spacer for relatively increasing the thickness of the end portion of the conductor wire is mounted in the insulating layer, and the width dimension of the conductor wire corresponding to the position where the spacer is mounted is changed to another position. By setting the width to be larger than the width of the conductor line, the internal impedance is unified along the longitudinal direction of the flexible flat wiring board.

The invention according to claim 7, wherein a plurality of conductor wires are provided in parallel on one surface of the insulating layer, and a ground layer is formed on a plane on the other surface of the insulating layer, And a method for adjusting the internal impedance of a flexible flat wiring board having a protective layer formed on the outer surface of the ground layer, wherein a plurality of insulating films are selected from among a plurality of types of insulating films having different thicknesses and / or dielectric constants. Are selected and laminated, and the internal impedance of the flexible flat wiring board is adjusted by setting the thickness and the dielectric constant of the insulating layer according to the combination of the insulating films.

The invention according to claim 8 is the method for adjusting the internal impedance of a flexible flat wiring board according to claim 6, wherein a plurality of types of insulating films having different thicknesses and / or dielectric constants are selected. Insulating film is selected and laminated, and the internal impedance of the flexible flat wiring board is adjusted by setting the thickness and dielectric constant of the insulating layer according to the combination of the insulating films.

According to a ninth aspect of the present invention, there is provided a method for adjusting the internal impedance of a flexible flat wiring board according to any one of the sixth to eighth aspects, wherein at least one part of the flexible flat wiring board in the longitudinal direction including at least a part thereof is curved. The reinforcing layer for adjusting the thickness outside the conductor wire is formed so that the conductor wire is located at the center in the thickness direction in the region of the portion or the entire region.

[0017]

FIG. 1 is a perspective view showing a flexible flat wiring board according to an embodiment of the present invention, and FIG.
FIG. 3 is a diagram showing the width dimension of the conductor wire at the end of the flexible flat wiring board, FIG. 3 is a sectional view taken along line AA of FIG. 1, and FIG.
It is -B sectional drawing. Hereinafter, a preferred example of the flexible flat wiring board will be described.

A predetermined connector (not shown) is attached to an end of the flexible flat wiring board, for example, and a plurality of conductor wires are connected to a main board of a personal computer, a screen LCD device, and the like via the connector. As shown in FIGS. 1 to 4, a plurality (for example, about 2
(Zero) conductor wires 1 are intermittently arranged at regular intervals in the horizontal direction, and an earth layer 3 as a copper foil, for example, is separated from the conductor wires 1 in the thickness direction via an insulating layer 2. And covered with protective layers 4 and 5 from both sides. Reference numeral 6 in FIGS. 3 and 4 indicates an adhesive.

Here, the larger the widths W1 and W2 (FIGS. 3 and 4) of the conductor wires 1 are, the larger the area per unit length of the conductor wires 1 is. The reactance (impedance) of the capacitor formed in a pseudo manner with the ground layer 3 is reduced. Conversely, the smaller the widths W1 and W2 of the conductor wires 1 are, the greater the impedance between these conductor wires 1 and the ground layer 3 is (first correlation).

The distances T1, T2 in the thickness direction between the conductor wire 1 and the earth layer 3 determine the reactance (impedance) of the capacitor formed by the conductor wire 1 and the earth layer 3. As the distances T1 and T2 increase, the reactance (impedance) of the simulated capacitor increases. Conversely, when the separation distances T1 and T2 between the conductor wire 1 and the ground layer 3 are small, the impedance of the capacitor formed simulated by these becomes small (second correlation).
More specifically, as shown in FIG.
Is W, and the distance between the conductor wire 1 and the earth layer 3 is T1,
Assuming that T2 is T, the dielectric constant of the insulating layer 2 is ε, and a predetermined coefficient is α, the capacitance C is expressed by the following equation (1). It can be seen that the capacitance C decreases (the internal impedance increases).

C = α · ε · W / T (1) Then, in the flexible flat wiring board of this embodiment, while obtaining the same internal impedance (50 Ω or 75 Ω, etc.) as that of a conventional micro coaxial cable, In order to maintain the same internal impedance along the longitudinal direction, the separation distances T1, T2 between the conductor wire 1 and the ground layer 3
Is changed, the width dimension W of the conductor wire 1 is correspondingly changed.
By setting 1, W2, the internal impedance is set uniformly along the longitudinal direction of the flexible flat wiring board.

More specifically, as shown in FIGS. 3 and 4, the insulating layer 2 is composed of a plurality of insulating films 7a and 7b and an adhesive 8, and these are arbitrarily combined to obtain a thickness T1 of the insulating layer 2.
Can be set freely and easily. Each insulating film 7a, 7b is a film body 9a, 9b, respectively.
Adhesives 10a and 10b are applied to one surface of the insulating films 7a and 10b, and are prepared in advance. The thicknesses and the dielectric constants of the plurality of insulating films 7a and 7b are set differently. The insulating layer 2 is formed by selecting a combination of a plurality of the insulating films 7a and 7b. That is, by selecting and laminating the insulating films 7a and 7b and the adhesive 8 in combination, the thickness T1 of the insulating layer 2 is set to a certain allowable level, the separation P1 between the conductor wires 1 and the conductor wire By setting the width dimension W1 of 1, the internal impedance between each conductor wire 1 and the ground layer 3 can be easily set to a predetermined value (50Ω or 75Ω or the like). Although only two insulating films 7a and 7b are used here, three or more insulating films may be used for lamination. Thus, the insulating films 7a, 7
Various materials are prepared in advance as the materials of the film bodies 9a and 9b and the adhesives 10a and 10b, and the thicknesses of the film bodies 9a and 9b and the adhesives 10a and 10b are also set to various dimensions. If it leaves, each insulating film 7a,
The dielectric constant of the adhesive 7b and the adhesive 8 can be made different from each other, and an arbitrary internal impedance can be set by a combination of the insulating films 7a and 7b and the adhesive 8. At this time, the width dimension W1 of the conductor wire 1 is set according to the separation distance T1 between the conductor wire 1 and the ground layer 3. At this time, the distance between the adjacent conductor wires 1 is P1.

The connecting portion (that is, the end in the longitudinal direction) 11 of the flexible flat wiring board with the connector is reinforced for the purpose of conforming to the shape of the connector and for easy gripping at the time of fitting to the connector. For this purpose, a spacer 12 and an adhesive 13 are interposed in the insulating layer 2. That is, a flexible flat wiring board is generally
Since it is necessary to bend at the time of the installation, it is necessary to ensure flexibility as much as possible, and it is necessary to suppress the thickness dimension T1 of the insulating layer 2 to a predetermined thickness which is as thin as possible. Depending on the requirements of the place where the flexible flat wiring board is laid, there is a case where the thickness of the flexible flat wiring board is desired to be reduced. On the other hand, it is preferable that the conductor wire 1 and the ground layer 3 be connected at an end portion which is a connection portion with the connector, with the conductor wire 1 and the ground layer 3 being separated by a distance T2 larger than the thickness T1. In particular, for example, when making a connection while sandwiching both ends of the end of the flexible flat wiring board with a connector, the thickness of the flexible flat wiring board should be more than a predetermined thickness as much as possible to maintain the connection strength. It is desirable to set. It is desirable that the thickness of the end portion of the flexible flat wiring board is set to be larger than that of the intermediate portion 14 even in consideration of ease of gripping at the time of connection.

Therefore, a spacer 12 and an adhesive 13 are interposed in the insulating layer 2 of the connection part 11 of the flexible flat wiring board with the connector, so that the conductor wire 1 and the ground layer 3 are connected to the connection part 11 of the flexible flat wiring board. Is set to T2 (> T1). Here, spacer 1
The total thickness of 2 and the adhesive 13 is (T2-T1).

As described above, the distance T2 between the conductor wire 1 and the ground layer 3 is set to be larger than T1, but the distance between the conductor wire 1 and the ground layer 3 in the flexible flat wiring board is partially reduced. If T1 and T2 are set to different values, the internal impedance of the region denoted by reference numeral 11 will be larger than the internal impedance of the region denoted by reference numeral 14 unless the width dimension W1 of the conductor wire 1 is changed. Impedance cannot be kept constant.

Therefore, in the portion 11 where the separation distance between the conductor wire 1 and the ground layer 3 is set to T2, the width W
1 is set large so that the internal impedance is kept constant over the entire length of the flexible flat wiring board. In this case, the line axis of the conductor wire 1 is not changed as compared with the intermediate portion 14 of the flexible flat wiring board, and the distance between the adjacent conductor wires 1 is set smaller than P1.

The ground layer 3 is formed over the front surface of the flexible flat wiring board, and is formed, for example, in a net shape to ensure the flexibility of the flexible flat wiring board.

In the flexible flat wiring board according to the present embodiment, the conductor wire 1 is connected to the flexible flat wiring board in a region including a portion which is expected to be frequently bent in the intermediate portion 14 in the longitudinal direction of the flexible flat wiring board. As shown in FIGS. 1, 3, and 4, a reinforcing layer 18 for adjusting the thickness of the outside (upper side) of the conductor wire 1 is formed so as to be located at the center in the thickness direction of the plate. As the reinforcing layer 18, an adhesive film in which an adhesive 18b is formed in advance on the lower surface of an insulating resin sheet 18a made of polyimide or the like is used. The thickness of the reinforcing layer 18 is the total thickness of the insulating layer 2 and the earth layer 3. Is set approximately. The region where the reinforcing layer 18 is formed may be limited to a partial region in the longitudinal direction of the flexible flat wiring board, or may be formed in the entire region. Thereby, the thickness of the flexible flat wiring board including the reinforcing layer 18 is set to a predetermined thickness dimension of, for example, 500 μm or less.

Such a flexible flat wiring board is manufactured, for example, as follows. The insulating films 7a, 7
b is an adhesive 10a on one surface of the film bodies 9a, 9b.
It is assumed that 10b is applied and formed in advance.

As a preliminary step, the value of the internal impedance required as a product is determined, the thickness T1 of the insulating layer 2 suitable for the internal impedance is determined, and an appropriate insulating film 7a is obtained from several types of insulating films. , 7
b and the adhesive 8 are selected.

Then, a large sheet having the adhesive 6 applied to one side of the protective layer 4 is prepared. Next, the adhesive 10
A plurality of conductor wires 1 are arranged in parallel on the surface a. In particular,
After the conductor foil is formed on the entire surface of the adhesive material 10a, a mask process is performed to remove a part thereof, thereby forming the conductor wires 1 in parallel.

At this time, the width dimension W1 of the conductor wire 1 is set to be larger at the portion denoted by reference numeral 11 (end portion of the wiring board) in FIG. The spacing dimension P1 between the conductor wires 1 is reduced. still,
Along with this, each conductor line 1 is formed so as to expand toward the portion of the reference numeral 11 between the portion of the reference numeral 11 and the portion of the reference numeral 14.

Then, in the large sheet having the adhesive 6 applied to the lower surface of the protective layer 4, the connector connecting portion of the flexible flat wiring board is cut out, and the conductor wire 1 is formed on the upper surface of the first insulating film 7a. The sheet in which the cutout portion of the sheet (the protective layer 4 and the adhesive 6) is covered so as to expose the conductor wire 1 is further stuck to the upper surface of the film in the state where the film has been set.

The ground layer 3 is formed on the surface of the sheet 9b shown in FIG. 4 in which the adhesive 10b is applied to one surface of the sheet on the adhesive 10b side. Since the ground layer 3 is desirably formed in a net shape, a pattern etching process is performed by a mask process to form the net shape.

Then, in a large sheet in which the adhesive 6 is applied on the upper surface of the protective layer 5, the connector connecting portion of the flexible flat wiring board is cut out, and the ground layer 3 is formed on the lower surface of the second insulating film 7b. On the film in the state of being made, the lower surface is further adhered so that the cutout portion of the sheet (the protective layer 5 and the adhesive 6) exposes the ground layer 3.

After the adhesive 8 is applied to the surface of the first insulating film 7a on the film body 9a side, the spacer 12 and the adhesive 8 are interposed between the first insulating film 7a and the second insulating film 7b. The spacer 12 and the first insulating film 7a are welded with the adhesive 8 by a heating vacuum laminating step, and the second insulating film 7b and the spacer 1
2 are welded and then cut into a predetermined shape by a predetermined cutting die. Finally, a reinforcing layer 18 is attached to a desired region on the upper surface of the flexible flat wiring board, and
Then, solder platings 16 and 17 are formed on portions of the upper surface and the lower surface of the ground layer 3 which face the respective notches (see FIG. 4), thereby completing a flexible flat wiring board. In this way, the flexible flat wiring board of this embodiment can be easily manufactured. Also,
By providing the reinforcing layer 18, when the flexible flat wiring board is bent, the conductor wire 1 is arranged at the center in the thickness direction of the flexible flat wiring board, so that the stress accompanying the bending is reduced around the flexible flat wiring board. And the radius of curvature when the conductor wire 1 is curved can be maintained relatively large as compared with the case where the reinforcing layer 18 is not provided. Therefore, the durability of the conductor wire 1 can be improved.

In the above-described embodiment, an example has been described in which the internal impedance is equivalent to that of the ultrafine coaxial cable of the LVDS system.
Of course, the present invention may be applied to a cable having an internal impedance equivalent to that of a micro coaxial cable employing the DS system, the LDI system or the GVIF system.

Further, in the above embodiment, the insulating layer 2 is formed to have a plurality of insulating films 7a and 7b, but only one of the prepared insulating films 7a and 7b is selected. However, only this one insulating film may be used as the insulating layer 2.

Furthermore, in the above-described embodiment, the mesh layer is used as the earth layer 3, but a flat earth layer 3 formed uniformly thin may be used.

Although each of the above-mentioned insulating films is formed with an adhesive in advance, the film may be directly adhered without an adhesive.

[0041]

According to the first, third, seventh and eighth aspects of the present invention, a plurality of insulating layers for separating a plurality of conductor wires from a ground layer are provided. Since a laminated insulating film is used, it is extremely easy to adjust the thickness of the insulating layer, that is, the separation dimension between the conductor wire and the ground layer, and it is possible to easily adjust the internal impedance. .

According to the second and sixth aspects of the present invention, when the distance between the conductor wire and the ground layer in the thickness direction must be increased when connecting to the connector, the distance between the conductor and the ground layer must be increased. The increase can be compensated for by an increase in the width of the conductor line, and when flexibility is required, the distance in the thickness direction between the conductor line and the ground layer must be reduced. This can be compensated for by a decrease in the width dimension, and as a result, there is an effect that the internal impedance of the flexible flat wiring board can be made uniform, including the connection portion with the connector.

In particular, a plurality of types of insulating films having different thicknesses and / or different dielectric constants are selected from the plurality of types, and these are laminated to form a conductor. Since it is interposed between the wire and the ground layer, the thickness and the internal impedance can be easily adjusted by the combination.

According to the fifth and ninth aspects, by providing the reinforcing layer, when the flexible flat wiring board is curved, the conductor wire can be arranged at the center in the thickness direction of the flexible flat wiring board. . Therefore, it is possible to minimize the stress strain applied to the conductor wire due to the bending, and it is possible to improve the durability of the conductor wire.

[Brief description of the drawings]

FIG. 1 is an external perspective view showing a flexible flat wiring board according to one embodiment of the present invention.

FIG. 2 is a diagram showing a width dimension of a conductor wire at an end of a flexible flat wiring board according to one embodiment of the present invention.

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 is a sectional view taken along line BB of FIG. 1;

FIG. 5 is a schematic diagram showing a flexible flat wiring board according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conductor wire 2 Insulating layer 3 Earth layer 7a, 7b Insulating film 12 Spacer 18 Reinforcing layer

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H01B 7/08 H01B 7/08 H05K 1/11 H05K 1/11 D (72) Inventor Masahiro Ito Nishisuehiro, Yokkaichi, Mie Prefecture 1-114, Sumidenso Mediatech Co., Ltd. (72) Inventor Masayuki Yagyu 1-114, Nishisuehiro-cho, Yokkaichi-shi, Mie Prefecture Inside Sumidenso Mediatech Co., Ltd. (72) Inventor Kenji Ikeda, Nishi-Suehiro, Yokkaichi-shi, Mie No. 1-14, Sumitomo Electric Industries Co., Ltd. (72) Inventor Kazuya Kakiuchi 2-1-1 Kagahara, Tsuzuki-ku, Yokohama-shi, Kanagawa Prefecture Inside Kyocera Elco Co., Ltd. 2-1-1 Kagahara Inside Kyocera Elco Co., Ltd. (72) Inventor Tsutomu Kaneko 852 Susagi, Sagara-cho, Haibara-gun, Shizuoka Prefecture F-term in Hachimaru Electronics Co., Ltd. (Reference) CC01 CC04 CC06 CD13 CD14 CD32 EE13 5G309 FA01 FA02 FA07 5G311 CA01 CB01 CD03 CD10 CF02 CF04

Claims (9)

[Claims] 1. A plurality of conductor wires are arranged in parallel on one surface of an insulating layer, a ground layer is formed on a plane on the other surface of the insulating layer, A flexible flat wiring board having a protective layer formed on a surface thereof, wherein the insulating layer has a plurality of laminated insulating films. 2. A plurality of conductor wires are provided side by side on one surface of the insulating layer, a ground layer is formed on a plane on the other surface of the insulating layer, A protective layer is formed on a surface of the flexible flat wiring board, wherein the conductor wire and the ground layer are connected to a predetermined connector or a predetermined board at a longitudinal end. The insulating layer is formed at the longitudinal end. A predetermined insulating spacer for relatively increasing the thickness of the end portion of the conductor wire is mounted in the insulating layer, and the width dimension of the conductor wire corresponding to the position where the spacer is mounted is different from that of the other position. A flexible flat wiring board set to be larger than the width of the conductor wire. 3. The flexible flat wiring board according to claim 2, wherein the insulating layer has a plurality of laminated insulating films. 4. The flexible flat wiring board according to claim 1, wherein each of the insulating films is selected from a plurality of types of insulating films having different thicknesses and / or different dielectric constants. Flat wiring board. 5. The flexible flat wiring board according to claim 1, wherein the conductor wire is provided in at least a part or all of a region in a longitudinal direction including at least a part that is curved. A flexible flat wiring board, wherein a reinforcing layer for adjusting the thickness of the outside of the conductor wire is formed so as to be located at the center in the thickness direction. 6. A plurality of conductor wires are provided side by side on one surface of the insulating layer, and a ground layer is formed on a plane on the other surface of the insulating layer. A method for adjusting the internal impedance of a flexible flat wiring board having a protective layer formed on a surface thereof, wherein a thickness of an end of the insulating layer is relatively set at an end in a longitudinal direction connected to a predetermined connector or a predetermined substrate. A predetermined insulating spacer for increasing the size is mounted in the insulating layer, and the width of the conductor line corresponding to the position where the spacer is mounted is made larger than the width of the conductor wire at another position. A method for adjusting the internal impedance of a flexible flat wiring board in which the internal impedance is unified along the longitudinal direction of the flexible flat wiring board by setting a large value. 7. A plurality of conductor wires are provided side by side on one surface of the insulating layer, and a ground layer is formed on a plane on the other surface of the insulating layer. A method for adjusting the internal impedance of a flexible flat wiring board on which a protective layer is formed on a surface, wherein a plurality of insulating films are selected and laminated from a plurality of types of insulating films having different thicknesses and / or dielectric constants, A method for adjusting the internal impedance of a flexible flat wiring board, wherein the internal impedance of the flexible flat wiring board is adjusted by setting the thickness and the dielectric constant of the insulating layer according to the combination of the insulating films. 8. The method for adjusting the internal impedance of a flexible flat wiring board according to claim 6, wherein a plurality of insulating films are selected from a plurality of types of insulating films having different thicknesses and / or dielectric constants. A method for adjusting the internal impedance of a flexible flat wiring board, wherein the internal impedance of the flexible flat wiring board is adjusted by stacking and setting the thickness and the dielectric constant of the insulating layer by a combination of the insulating films. 9. The method for adjusting the internal impedance of a flexible flat wiring board according to claim 6, wherein at least a part or all of a region in a longitudinal direction including at least a part that is curved. 3. The method for adjusting the internal impedance of a flexible flat wiring board according to claim 1, wherein a reinforcing layer for adjusting the thickness outside the conductor wire is formed so that the conductor wire is positioned at the center in the thickness direction.