JP2001111181A - Flexible wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible wiring board whose wiring pattern is hardly disconnected. SOLUTION: The junction parts 23a of the lands 24 and wiring patterns 23 of a flexible wiring board 16 are arranged in a region 5A on which an electronic component 5 is mounted. The boundaries 10 between the wiring patterns 23 extended from the lands 24 and electrical junction parts 8 are formed directly under the electronic component 5. Even if the flexible wiring board 16 is bent, the boundaries 10 between the wiring patterns 23 and the electrical junction parts 8 and their neighborhoods are kept flat by the electronic component 5, so that the disconnection in the wiring pattern can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible wiring board which is incorporated into various products with bending and bending after mounting an electronic component, and more particularly to a flexible wiring board having a characteristic wiring pattern.

[0002]

2. Description of the Related Art Conventionally, as an electronic circuit board used for electronic equipment and the like, a wiring pattern is formed on a flexible substrate made of polyimide or the like and having flexibility, and an appropriate circuit wiring is formed. 2. Description of the Related Art A flexible wiring board configured to be freely bent or curved by being mounted via a connector is well known.

FIGS. 5 and 6 are a schematic plan view and a schematic sectional view showing a conventional flexible wiring board.

The flexible wiring substrate 1 has a flexible substrate 2 made of polyimide or the like having a wiring pattern 3 on the surface and having flexibility and capable of bending and bending.

[0005] The wiring pattern 3 includes a part of an electronic component 5.
And a land 7 electrically connected to the terminal portion 6 of
Further, on the surface on the side where the wiring pattern 3 is provided, a cover 4 which is a protective member having an insulating property and covers a portion other than the opening 4a formed at a location corresponding to the land 7 is arranged.

The electronic component 5 has its terminals 6 and lands 7 electrically and mechanically connected via an electrical connection 8 formed by electrical connection means such as soldering. It is mounted on the flexible substrate 2.

The flexible board 2 on which the electronic components 5 are mounted, that is, the flexible wiring board 1 is bent or bent in accordance with the size and shape of the space to be arranged when assembled into a product (not shown) to have a desired shape. Is transformed into

[0008]

However, when the flexible wiring board 1 is bent or bent into a desired shape, the bent portion 9 is connected to the electrical connection portion 8 and the wiring pattern 3.
In the case of being located near the boundary 10, the stress caused by bending concentrates locally on the boundary 10, and this boundary 10
There is a possibility that the wiring pattern 3 may be disconnected in the vicinity.

As a flexible wiring board in consideration of such a disconnection, as shown in a schematic sectional view of FIG.
A reinforcing plate 12 for keeping the vicinity of the boundary 10 flat is provided on the back surface of the flexible substrate 2 near the boundary where the electronic component 5 is mounted, particularly near the boundary 10 between the electrical connection portion 8 and the wiring pattern 3. A flexible wiring board 11 that relieves stress at a boundary portion 10 due to bending is well known.

However, such a flexible wiring board 11 is not only thickened by the reinforcing plate 12 and consequently leads to an increase in volume, but also to a cost due to an increase in the number of components and the accompanying steps. To rise.

Further, as shown in FIG.
4, a plurality of joints, each of which is electrically connected to the same land 7, for example, two joints 1
By forming the 4a and 14b, a flexible wiring board that increases the number of boundaries 10 between the electrical connection portion 8 and the wiring pattern 14 to two (a plurality), reduces the probability of disconnection, and avoids disconnection of the wiring pattern 14 13 is also well known.

However, the flexible wiring board 13 can only reduce the probability of disconnection, but cannot completely prevent the disconnection, and the area of the flexible wiring board 13 increases with the branching of the wiring pattern 14. I do.

Further, as shown in FIG. 9, the land 22 is made larger with respect to the opening 4a of the cover 4 so that the electrical connection 8 is formed so as to be connected only to the land 22.
Flexible wiring boards 15 that allow the wiring pattern 3 to be completely covered by the cover 4 are also well known.

However, the flexible wiring board 15 does not strictly control the amount of displacement of the cover 4 so that the opening 4a does not protrude from the land 22 and cover the wiring pattern 3 due to the displacement of the cover 4. This has the disadvantage of lowering productivity.

In addition, in order to ensure that the cover 4 and the land 22 overlap with each other, the land 22 must be provided extremely large in order to obtain a sufficient overlapping amount D. Not only increases but also the cost.

The present invention has been made in consideration of the above-described points, and without increasing the number of parts and the board area.
It is an object of the present invention to provide a flexible wiring board capable of preventing disconnection while maintaining dimensional control at a conventional level.

[0017]

SUMMARY OF THE INVENTION A flexible wiring board according to the present invention comprises a flexible board which can be bent and bent, a wiring pattern formed on the surface of the flexible board, and a part of the wiring pattern. A land electrically connected to the terminal of the electronic component; a protective member having an insulating property arranged to cover at least a part of the wiring pattern; and an electrical member electrically connecting the terminal to the land. A flexible wiring board having a connection portion, wherein a joint between the land and the wiring pattern is formed immediately below the electronic component in a region where the electronic component is mounted.

As a result, the boundary between the electrical connection and the wiring pattern and the vicinity thereof can be kept flat by the mounted electronic component, so that the stress caused by bending is locally applied to the above-mentioned boundary. As a result, it is possible to provide a flexible wiring board that can prevent the occurrence of disconnection of the wiring pattern without increasing the number of components and the board area, and maintaining the same dimensional control as before.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention provides a flexible substrate that can be bent and bent, a wiring pattern formed on a surface of the flexible substrate, and a wiring pattern provided on a part of the wiring pattern. A land that is electrically connected to the terminal of the electronic component, a protective member having an insulating property arranged to cover at least a part of the wiring pattern, and electrically connects the terminal and the land. A flexible wiring board having an electrical connection portion, wherein a bonding portion between the land and the wiring pattern is formed immediately below the electronic component in a region where the electronic component is mounted, thereby forming a flexible wiring board. This has the effect that the junction between the electrical connection and the wiring pattern and the vicinity thereof can be kept flat by the mounted electronic component.

According to a second aspect of the present invention, there is provided the flexible wiring board according to the first aspect, wherein the wiring pattern is provided on the flexible substrate via a through hole provided in the flexible substrate immediately below the electronic component. And is connected to a wiring pattern formed on the back surface or another layer, and has the same function as the first aspect.

(Embodiment) Hereinafter, a flexible wiring board according to the present invention will be described with reference to the drawings.

FIGS. 1 and 2 are a schematic plan view and a schematic sectional view, respectively, showing an embodiment of a flexible wiring board according to the present invention. In the figure, components having the same reference numerals as those in FIG. Is shown.

The flexible wiring board 16 of the present embodiment
Also has basically the same components as the conventionally known flexible wiring board 1 previously shown in FIGS. 5 and 6, that is, it is made of polyimide or the like and has flexibility and can be bent and bent. Flexible substrate 2, wiring pattern 23 formed on the surface of flexible substrate 2 and land 2
4, and an opening 4a for exposing the land 24
And a cover 4 that covers the surface of the wiring pattern 23 with

However, as is clear from FIG. 1, the flexible wiring board 16 of the present embodiment is different from the conventionally known flexible wiring board 1 shown in FIGS. Joint 2 with
3a is configured to be located in a region 5A where the electronic component 5 is mounted.

Accordingly, the terminal portions 6 of the electronic component 5 are electrically connected to the lands 24 by forming the electrical connection portions 8 such as soldering in the openings 4 a of the cover 4, and are connected to the flexible wiring board 16. Land 2
The boundary 10 between the wiring pattern 23 extending from 4 and the electrical connection 8 is formed immediately below the electronic component 5.

For this reason, the flexible wiring board 16
Even if the bent portion 9 is bent or bent into a desired shape according to the arrangement space or the like of the product to be incorporated, the boundary portion 1
Since the portion where 0 is formed and the vicinity thereof are always kept flat by the electronic component 5, the stress applied to the boundary portion 10 with the bending of the bending portion 9 is reduced.

As a result, disconnection of the wiring pattern 23 at the boundary 10 between the electrical connection portion 8 and the wiring pattern 23 can be prevented.

FIGS. 3 and 4 are a schematic plan view and a schematic sectional view, respectively, showing another embodiment of the flexible wiring board according to the present invention. In the drawings, components having the same reference numerals as those in FIGS. 1 and 2 have the same functions. Element.

As is clear from the drawings, the flexible wiring board 17 of the present embodiment is an example in which a multi-terminal electronic component 18 is assumed as an electronic component to be mounted.

In the case of the multi-terminal electronic component 18, the electronic component 1
Depending on the shape of the wiring pattern 8, it may be difficult to form the wiring pattern 19 corresponding to the number of terminals directly below the mounting position. Is considered in the arrangement.

Also in this embodiment, a plurality of lands 25 corresponding to the number of terminals of the electronic component 18 provided on a flexible substrate 21 made of polyimide or the like and having flexibility and capable of bending and bending are provided. The plurality of joints 19a with the wiring pattern 19 extending from each of the lands 25
As in the previous embodiment, the area 1 where the electronic component 18 is mounted
8A.

Further, region 1 where electronic component 18 is mounted
A through hole 20 penetrating in the thickness direction is provided in a flexible substrate 21 in 8A.

The through hole 20 is formed on the flexible substrate 21
The wiring pattern 19 is formed through the through hole 20 to connect to the wiring 19b disposed on the back surface of the flexible substrate 21 or another layer (not shown) through the through hole 20. Is done.

The flexible wiring board 17 of the present embodiment
Also, by mounting the electronic component 18, a plurality of joints 19a between the wiring pattern 19 extending from the land 25 and the land 25 are formed directly below the multi-terminal electronic component 18, so that the wiring pattern 19 and the electrical Boundary 1 with Dynamic Connection 8
0 and its vicinity are always kept flat, so that the stress on the boundary 10 due to the bending of the bending portion 9 is reduced, and the boundary 1
The disconnection of the wiring pattern 19 at 0 can be prevented. further,
The wiring pattern 19 composed of a large number of wirings can be distributed to both the front and back surfaces of the flexible substrate 21 or to a plurality of layers.

[0035]

As described above, the flexible wiring board of the present invention is configured such that the joint between the land and the wiring pattern is located in the mounting area of the electronic component, and the electrical component and the land and the solder are formed by soldering or the like. Since the boundary between the electrical connection with the wiring pattern and the wiring pattern is located immediately below the mounted electronic component, the boundary and the vicinity thereof can be kept flat by the mounted electronic component. Therefore, it is possible to avoid concentration of stress on the above-mentioned boundary portion due to bending of the flexible wiring board. As a result, without increasing the number of parts and the board area, the occurrence of disconnection of the wiring pattern while maintaining the conventional dimensional management is possible. This has the effect of providing a flexible wiring board capable of preventing the occurrence of the problem.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing an embodiment of a flexible wiring board according to the present invention.

FIG. 2 is a schematic sectional view showing the same embodiment.

FIG. 3 is a schematic plan view showing another embodiment of the flexible wiring board according to the present invention.

FIG. 4 is a schematic cross-sectional view showing another embodiment.

FIG. 5 is a schematic plan view showing an example of a conventional flexible wiring board.

FIG. 6 is a schematic sectional view of the same example.

FIG. 7 is a schematic sectional view showing another example of a conventional flexible wiring board.

FIG. 8 is a schematic plan view showing still another example of a conventional flexible wiring board.

FIG. 9 is a plan view showing still another example of the conventional flexible wiring board.

[Explanation of symbols]

 2,21 Flexible board 4 Cover 4a Opening 5,18 Electronic component 6 Terminal 8 Electrical connection 9 Bend 10 Boundary 16,17 Flexible wiring board 19,23 Wiring pattern 19a, 23a Junction 19b Wiring 20 Through hole 24 , 25 Land

Claims (2)

[Claims] A flexible substrate capable of bending and bending, a wiring pattern formed on a surface of the flexible substrate, and a land provided on a part of the wiring pattern and electrically connected to a terminal of an electronic component. And a flexible wiring board comprising: a protective member having an insulating property disposed so as to cover at least a part of the wiring pattern; and an electrical connection portion that electrically connects the terminal and the land. A flexible wiring board, wherein a joint between the land and the wiring pattern is formed immediately below the electronic component in a region where the electronic component is mounted. 2. The wiring pattern according to claim 1, wherein the wiring pattern is connected to a wiring pattern formed on a back surface of the flexible substrate or another layer through a through hole provided in the flexible substrate immediately below the electronic component. The flexible wiring board as described.