JPH08130351A - Multilayer flexible wiring board - Google Patents

Abstract

PURPOSE: To make it possible to bend at the correct position on a multilayer wiring board, to prevent oppression of peripheral parts, and to secure the flatness of mounting parts of an electron part. CONSTITUTION: An electric part is mounted on the region 1A, where sufficient flatness can be obtained, of a multilayer flexible wiring board 1. Also, the region 1B only which is desired to be bent, and the layers other than the conductive layers 4 and 6, a board 5 located between them and coverage layers 11 and 12 are thinned off. As a result, the flexibility of the multilayer flexible wiring board is limited to the specific part which is thinned off, and they are bent at the suitable position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer flexible wiring board used in various electronic equipments and devices for mounting a plurality of electric circuit elements, and more particularly to a multilayer wiring board which is bent and wired in an appropriate place in the equipment. A flexible wiring board.

[0002]

2. Description of the Related Art In a device such as a camera, for example, the internal space in which various components and various mechanical parts are incorporated is extremely limited, and it is desired to incorporate and mount the components in as high a density as possible. Therefore, in such a camera or the like, there is little space for assembling a means for electrically connecting the mechanical parts to each other by wiring, a circuit board for mounting various electric circuit elements, and the like. Flexible wiring boards are generally used so that they can be arranged well.

By the way, in recent years, the multifunctionalization of cameras has rapidly progressed, and the electric circuit scale has increased accordingly. Such an increase in the scale of an electric circuit tends to increase the density of the wiring board and increase the number of constituent layers of the board from a single-layer board to a two-layer board.

However, such a flexible wiring board inevitably has a problem that it becomes difficult to bend as the number of constituent layers increases. In particular, when wiring around a narrow space between each mechanism and the cover parts, such as a camera, it is necessary to provide many bent parts at various places to be assembled. It is difficult to use such a flexible wiring board having a multilayer structure as it is.

Therefore, in this type of multilayer flexible wiring board, as shown in, for example, Japanese Utility Model Publication No. 4-6218, a cover lay (insulating film) is opened or opened at a portion where bending is required. The technique of providing a hole and making it easy to bend was generally adopted.

[0006]

However, even in the multilayer flexible wiring board having the above-described measures capable of being bent, it is difficult to bend the board as the number of layers increases. However, the flexibility originally used as a characteristic of the flexible substrate is impaired, which makes it difficult to fold it at an accurate position and presses the peripheral mechanical parts.

In such a flexible wiring board that is difficult to bend, it is difficult to assemble it into a narrow space inside a camera or the like, and the range of bending on the board is widened. However, there is a problem that it is impossible to secure the flatness in the mounting portion of the electric component, which originally wants to maintain the flatness, and it is desired to take some measures to eliminate such a problem. .

The present invention has been made in view of the above-mentioned circumstances, and the flexibility inherent in the flexible substrate is limited to a necessary area, so that the flexible substrate can be bent in various electric devices and apparatuses. Another object of the present invention is to obtain a multi-layer flexible wiring board that can be wired through a gap space and can be mounted with a plurality of electric circuit elements in a desired state.

[0009]

In order to meet such a demand, a multilayer flexible wiring board according to the present invention has a plurality of electric circuit elements mounted thereon and at least a plurality of conductive layers. When wiring is done by bending the part inside the device by bending it appropriately, the area that contributes to the bending part of this board is made thinner than the component mounting area, which results in sufficient planarity. The electric component is mounted in the region where it can be obtained, and flexibility is utilized only in the region to be bent by reducing the layer thickness.

Further, the multilayer flexible wiring board according to the present invention is configured such that the region contributing to the bent portion of the substrate is made thinner than the component mounting region, and the surface of the region contributing to the bent portion is formed. An opening region is provided in a part or all of the insulating layer, or a part of the region contributing to the bent portion is opened over the entire layer.

[0011]

According to the present invention, in a range in which it is desired to mount an electric component on a flexible wiring board which is incorporated and wired in a device such as a camera, the multi-layer state is maintained, flexibility is suppressed, and flatness is reduced. It is possible to increase the height, and by reducing the layer only in the area you want to bend, it is possible to bend at a more accurate position, which makes it easy to assemble wiring into a narrow and bent gap space at an appropriate place. It

Particularly, by providing an opening region in a part or the whole of the surface insulating layer in the bent portion region or by opening a part of this region over the entire layer, the flatness in the component mounting region and It is possible to further enhance the effect and exhibit the flexibility in the bending region.

[0013]

1 and 2 show an embodiment of a multilayer flexible wiring board according to the present invention. In these drawings, the multilayer flexible wiring board generally designated by reference numeral 1 has at least a plurality of layers ( In this embodiment, the wiring board has four conductive layers (conductor patterns) 2, 4, 6, and 8. Here, 3, 5 and 7 in the figure are thin substrates having a synthetic resin material such as polyester or polyimide as a base material, and the conductive patterns 2, 4, 6 and 8 are the surfaces of these substrates 3, 5 and 7, It is formed between and on the back surface.

Reference numerals 9, 10; 11 and 12 in the drawing denote coverlay layers made of an insulating film formed so as to cover the surface layers of the upper end surface and the lower end surface of the multilayer flexible wiring board 1. That is, a commonly-used double-sided flexible wiring board has conductor patterns formed on both surfaces of the board, and a coverlay layer is formed on the surface layer of each surface at a portion where insulation is required.

In this embodiment, in order to carry out the patterning of the conductor pattern more easily and in a space-saving manner, the conductor patterns 4, 6 on both sides of the double-sided flexible wiring substrate 5 are further arranged on the substrates 3, 5 respectively. Is formed, and the conductor patterns 2 and 8 and the coverlay layers 9 and 10 are similarly formed on the surface layer thereof. However, since the substrate 1 having the four conductor layers (2, 4, 6, 8) as described above has a thickness twice or more that of the double-sided flexible wiring substrate,
When bending this, it is difficult to bend it at the correct position.

According to the present invention, the multilayer flexible wiring board 1 having three or more conductive layers (conductive patterns 2, 4, 6, 8) is provided with a plurality of electric circuit elements 13, 14, 1.
An area 1A for mounting the components 5 and 16 and an area 1B that contributes to a bent portion (portion indicated by A in FIG. 1) for bending and assembling wiring in a device (not shown) such as a camera.
The area 1B contributing to this bent portion is divided into layers smaller than those of the component mounting area 1A, and the electrical components (13 to 1
6) is mounted, and only the region 1B desired to be bent is characterized in that flexibility can be utilized by reducing the layer thickness.

That is, according to the present invention, the multilayer flexible wiring board 1 is formed in order to accurately bend at the position of the bent portion A, as is apparent from FIGS. 1 and 2A. The region 1B near the position A is provided with the second and third conductive layers 4, 6 and the substrate 5 and the coverlay layers 10, 1 between them.
By omitting the layers other than 1, the layers are reduced. Then, when the bending region 1B is thinned in this way, the thickness of the substrate 1 in this portion is obviously reduced.
The flexibility of the can be limited to only certain parts due to the aforementioned depletion.

Therefore, according to the present invention as described above,
For example, in a range (area 1A) in which it is desired to mount the electric components 13 to 16 on the flexible wiring board 1 that is incorporated and wired in a device such as a camera, the multilayer state is maintained, flexibility is suppressed, and planarity is enhanced. In addition, only the region 1B desired to be bent can be bent at a more accurate position (folded portion A) due to the reduction of the layer thickness, so that the device can be bent in a narrow and appropriate place. Built-in wiring to the gap space can be done very easily and appropriately.

FIG. 3 shows another embodiment of the multilayer flexible wiring board 1 according to the present invention and is a schematic view of the board 1 viewed from the component mounting surface side. In this embodiment, as shown by reference numeral 20 in the figure, the coverlay layer 11, which is a surface insulating layer in the region 1B that contributes to the bent portion formed by reducing the layer in the substrate 1,
An opening region is provided in a part or all of 12. That is, the coverlay layers 11 and 12 are omitted in the bent region 1B where there is no pattern.

In this way, the flexibility in the region 1B that contributes to the bent portion of the substrate 1 is improved by the coverlay layers 11 and 12.
As a result, the flexibility can be further enhanced and exerted, whereby the flatness in the component mounting area 1A can be ensured and the component mounting can be performed easily and appropriately. .

FIG. 4 is a schematic perspective view of a substrate showing still another embodiment of the multilayer flexible wiring board 1 of the present invention,
In this embodiment, in the folded region 1B in which the number of layers is reduced in the multilayer flexible wiring board 1, a part of the region 1B that contributes to the folded portion is opened over all layers (4,5, 6, 11, 12). I am trying to form. 2 in the figure
1 is an opening formed in this way. By doing so, there is an advantage that the bending at the bent portion A in the region 1B contributing to the bent portion can be performed more easily and surely, and the bending is easy.

In particular, the opening 2 is formed in part or all of the surface insulating layer (coverlay layers 11 and 12) in the bent region 1B.
By providing 0 or opening a part of the region 1B by the opening 21 over the entire layer, the flatness in the component mounting region 1A and the flexibility in the bending region 1B can be improved.
It is possible to further enhance the effect and exert the effect.

The present invention is not limited to the structure of the embodiment described above, but the shape, structure, etc. of each part of the multilayer flexible wiring board 1 can be appropriately modified and changed, and various modifications are conceivable. For example, in the above-described embodiment, as the multilayer flexible wiring board 1, four conductive layers 2, 4, 6,
However, the present invention is not limited to this, and at least a plurality of layers (for example, three layers or more) can be applied to exert the effect. Further, in the above-described embodiment, the camera is exemplified as the device in which the wiring board 1 is incorporated, but it goes without saying that the invention is not limited to this.

[0024]

As described above, according to the multilayer flexible wiring board according to the present invention, a multilayer flexible wiring board having a plurality of electric circuit elements mounted thereon and having at least a plurality of conductive layers is provided inside a device. When wiring by assembling by bending properly with the bent part, the area contributing to the bent part of this board was reduced from the part mounting area, so even though it was a simple structure, it was multilayered. The electrical components should be mounted in the area where sufficient flatness can be obtained, and flexibility can be utilized by reducing the layer in the area to be bent, and accurate bending can be performed in the area to be bent of this wiring board. You can

Thus, according to the present invention, it is possible to prevent the peripheral mechanical parts from being pressed by the multilayer flexible wiring board, and to expand the area where the flatness of the multilayer flexible wiring board can be maintained. It is possible to perform high-density mounting of electric components, and at the same time, it is possible to avoid a defect such as contact failure of the electric components due to bending of the wiring board.

Further, according to the present invention, since the wiring board can be mounted at a more accurate position inside the equipment such as the camera, it is possible to make an accurate electrical connection with another flexible wiring board. There is also an advantage.

Further, according to the present invention, the region of the multilayer flexible wiring board that contributes to the bent portion is made thinner than the component mounting area, and the surface insulating layer of the region that contributes to the bent portion is formed. By providing an opening region in a part or all of, or by opening a part of the region that contributes to this bent portion over the entire layer, the required flexibility can be obtained at the required site, This has the advantage that the bending at the required position can be performed more reliably.

[Brief description of drawings]

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

2A and 2B are schematic cross-sectional views of the multilayer flexible wiring board shown in FIG. 1 taken along the center line in the longitudinal direction of FIG. 1, and FIG.

FIG. 3 is a schematic front view showing another embodiment of the multilayer flexible wiring board according to the present invention viewed from the component mounting surface of the board.

FIG. 4 is a schematic perspective view showing still another embodiment of the multilayer flexible wiring board according to the present invention.

[Explanation of symbols]

1 ... Multilayer flexible wiring board, 1A ... Component mounting area,
1B ... Bending region, 2 ... First layer conductive pattern, 3, 5,
7 ... Double-sided flexible wiring board, 4 ... 2nd layer conductive pattern, 6 ... 3rd layer conductive pattern, 8 ... 4th layer conductive pattern, 9 ... 1st coverlay layer, 10 ... 4th coverlay layer, 11 ... second coverlay layer, 12 ... third coverlay layer, 13,14,15,16 ... electric component, 20 ... opening of coverlay layer, 21 ... opening in board bending region.

Claims (4)

[Claims] 1. A multilayer flexible wiring board having a plurality of electric circuit elements mounted thereon, having at least a plurality of conductive layers, and being incorporated and wired in a device, wherein the multilayer flexible wiring board has a bent portion. The multilayer flexible wiring board is characterized in that it is configured to be bent and wired inside the device, and the region contributing to the bent portion is reduced in thickness from the component mounting region. 2. The multilayer flexible wiring board according to claim 1, wherein an area of the multilayer flexible wiring board that contributes to the bent portion is made thinner than a component mounting area and contributes to the bent portion. A multilayer flexible wiring board, characterized in that an opening region is provided in a part or all of the surface insulating layer. 3. The multilayer flexible wiring board according to claim 1, wherein an area of the multilayer flexible wiring board that contributes to the bent portion is made thinner than a component mounting area and contributes to the bent portion. A multilayer flexible wiring board, characterized in that a part of the above is opened over all layers. 4. The multilayer flexible wiring board according to claim 1, 2, or 3, wherein a camera is used as a device for incorporating and wiring the multilayer flexible wiring board.