JPH0888448A - Flexible printed circuit board - Google Patents

Abstract

PURPOSE: To provide a flexible printed circuit board which will not lose its flexibility and avoids cutting or breaking of its circuit pattern. CONSTITUTION: A reinforcing plate 38 is mounted on a base film 32 on a flexible printed circuit board 30 and the end face 38B of this plate is formed into a wavy face. Accordingly, the film 32 and circuit pattern 32A are folded along the end face 38B moderately within the range between the top and bottom of this end face and this prevents the stress from concentrating on the folded parts of the board 30. Thus, the disconnection and breaking of the circuit pattern little occur.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible printed circuit board, and more particularly to a flexible printed circuit board used for wiring electronic equipment such as cameras and printers.

[0002]

2. Description of the Related Art In recent years, flexible printed boards have been used in electric circuits of electronic devices such as cameras and printers. Known examples of this flexible printed circuit board are shown in FIGS. 6 and 7. In the flexible printed circuit board 10 shown in FIG. 6, a copper foil is printed on the surface of the base film 12, so that the circuit pattern 14 is formed on the surface of the base film 12. Circuit pattern 1
A cover lay 16 is attached to the surface of 4. In this case, the surface of the right end portion of the circuit pattern 14 is exposed.

A reinforcing plate 18 is attached to the rear surface of the right end portion of the base film 12. As a result, the right end portion of the flexible printed board 10 is reinforced by the reinforcing plate 18, so that the right end portion of the flexible printed board 10 is inserted into the connector (not shown) and the circuit pattern 14 is inserted.
The right end of the can be connected to a terminal in the connector.

In the flexible printed board 20 shown in FIG. 7, a copper foil forming an upper circuit pattern 24A is printed on the surface of a base film 22, and an upper cover lay 26A is attached to the surface of the upper circuit pattern 24A. There is. Further, a copper foil forming a lower circuit pattern 24B is printed on the back surface of the base film 22, and a lower cover lay 26B is attached to the back surface of the lower circuit pattern 24B.

A reinforcing plate 28 is attached to the back surface of the lower cover lay 26B. As a result, the flexible printed circuit board 20 is reinforced by the reinforcing plate 28, so that the flexible printed circuit board 20 can be fixed to the device body or the like via screws or double-sided tape. The flexible printed circuit board 20 shown in FIG.
Since A and the lower circuit pattern 24B are provided in two layers, the circuit wiring can be efficiently arranged as compared with the flexible printed board 10 of FIG.

[0006]

The reinforcing plates 18 and 28 shown in FIGS. 6 and 7 are each formed in a rectangular shape. Therefore, in the case of the reinforcing plate 18 of FIG. 6, since the flexible printed circuit board 10 is bent linearly along the left end surface A of the reinforcing plate 18, bending stress concentrates on the bent portion. As a result, the flexible printed circuit board 10 may be cut along the left end surface A of the reinforcing plate 18 or the circuit pattern 14 may be broken.

Further, in the case of the reinforcing plate 28 of FIG. 7, the flexible printed circuit board 20 is bent linearly along the left end surface B and the right end surface C of the reinforcing plate 28, so that bending stress concentrates on the bent portion. As a result, the flexible printed circuit board 20 has the left end surface B and the right end surface C of the reinforcing plate 28.
There is a problem that the upper circuit pattern 24A and the lower circuit pattern 24B are disconnected along the line.

As a method of solving this problem, a method of increasing the thickness of the base film of the flexible printed circuit board to make the flexible printed circuit board strong against bending stress is conceivable. However, if the thickness of the base film is increased, it is flexible. There is a problem that the flexibility of the printed circuit board is impaired. The present invention has been made in view of such circumstances, and prevents the occurrence of cutting or circuit pattern disconnection along the end surface of the reinforcing plate, and a flexible printed board formed so as not to impair flexibility. The purpose is to provide.

[0009]

According to the present invention, in a flexible printed circuit board in which a circuit pattern is sandwiched between a base layer and a cover layer, a reinforcing plate is attached to the base layer, and an end face of the reinforcing plate is attached. The feature is that it is formed in a curved shape.

[0010]

According to the present invention, the reinforcing plate is attached to the base layer of the flexible printed board, and the end surface of the reinforcing plate is formed into a curved shape. Therefore, when the base layer or the circuit pattern bends along the end face of the reinforcing plate, the bending is gentle within the range between the top and the bottom of the curved end face of the reinforcing plate, so stress concentrates on the bent portion of the flexible printed circuit board. Can be prevented.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the flexible printed circuit board according to the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a perspective view of the flexible printed circuit board 30,
The flexible printed board 30 includes a base film (base layer) 32. The base film 32 is formed of, for example, a polyimide resin in a strip shape. Circuit patterns 34A, 34B, 34C are formed on the surface of the base film 32.
Copper foil is printed to form ... A cover lay (cover layer) 36 is attached to the surfaces of the circuit patterns 34A, 34B, 34C ... With the right end surface of the circuit patterns 34A, 34B, 34C ... Exposed.
Like the base film 32, the coverlay 36 is made of a polyimide resin or the like.

A reinforcing plate 38 is attached to the back surface of the right end portion of the base film 32. The reinforcing plate 38 is made of glass epoxy resin or polyimide resin, and its right end face 38A is formed in a straight line so as to be flush with the right end face 32A of the base film 32. Further, the left end surface 38B of the reinforcing plate 38 is formed in a corrugated shape. The reinforcing plate 38
The shape of the left end surface 38B is not limited to a corrugated shape and may be a curved shape, for example, a gentle mountain shape.

The operation of the flexible printed board constructed as described above will be described. First, when the right end portion of the flexible printed circuit board 30 is inserted into or removed from the connector (not shown), the flexible printed circuit board 30 is bent along the left end surface 38B of the reinforcing plate 38. In this case, since the left end surface 38B of the reinforcing plate 38 is formed in a corrugated shape, the flexible printed board 30
Is gently bent within the amplitude range D (see FIGS. 2 and 3) of the waveform of the left end surface 38B of the reinforcing plate 38. Therefore, since stress is not concentrated on the bent portion of the flexible printed circuit board 30, it is difficult to cut at the bent portion and the circuit patterns 34A, 34B, 34C ... Are hard to break.

In the above-described embodiment, the case where the present invention is applied to the flexible printed circuit board 30 having the reinforcing plate 38 provided at the end has been described, but the present invention is not limited to this, and as shown in FIG. 4 and FIG. The present invention can also be applied to a flexible printed circuit board provided with a reinforcing plate in addition to the parts. Another embodiment will be described below with reference to FIGS.

As shown in FIG. 5, the flexible printed board 40 has a base film 42. The base film 42 is formed of a polyimide resin as in the above embodiment. Copper foil is printed on the surface of the base film 42 so as to form the circuit patterns 44A, 44B, 44C, .... Circuit patterns 44A, 44B, 44
Circuit patterns 44A, 44B, 44C are provided on the surface of C ...
The cover lay 46 is attached with the surfaces of both end portions of the cover exposed. Like the base film 42, the coverlay 46 is made of a polyimide resin or the like.

A reinforcing plate 48 is attached to the back surface of the right end portion of the base film 32. The reinforcing plate 48 is formed of glass epoxy resin or polyimide resin, and its right end surface 48A and left end surface 48B are formed in a corrugated shape. still,
The shape of both end surfaces 38A and 38B of the reinforcing plate 48 is not limited to a corrugated shape, and may be any shape as long as it is curved and may be, for example, a gentle mountain shape.

The operation of another embodiment configured as described above will be described. First, the flexible printed circuit board 40
The flexible printed circuit board 40 is bent along both end surfaces 48A and 48B of the reinforcing plate 48 when it is fixed to a device body (not shown) via screws or double-sided tape.
In this case, since both end surfaces 48A and 48B of the reinforcing plate 48 are formed in a corrugated shape, the flexible printed circuit board 40 has the waveform amplitude ranges E and F of the both end surfaces 48A and 48B of the reinforcing plate 48.
(Refer to FIG. 4 and FIG. 5) Bent gently. Therefore,
Since stress is not concentrated on the bent portion of the flexible printed circuit board 40, it is difficult to cut at the bent portion and the circuit patterns 44A, 44B, 44C ... Are hard to break.

[0018]

As described above, according to the flexible printed circuit board of the present invention, when the base layer and the circuit pattern are bent along the end face of the reinforcing plate, the curved end face of the reinforcing plate is formed with the top and the bottom. Since it bends gently within the range, it is possible to prevent stress from being concentrated on the bent portion of the flexible printed circuit board. This makes it difficult for the flexible printed circuit board to be cut at the bent portion without increasing the plate thickness of the base film, and it is also difficult for the circuit pattern to break. Furthermore, since it is not necessary to increase the thickness of the base film of the flexible printed circuit board, the flexibility of the flexible printed circuit board is not impaired.

[Brief description of drawings]

FIG. 1 is a perspective view showing a flexible printed circuit board according to the present invention.

FIG. 2 is a plan view showing a flexible printed circuit board according to the present invention.

FIG. 3 is a sectional view showing a flexible printed circuit board according to the present invention.

FIG. 4 is a plan view showing another embodiment of the flexible printed circuit board according to the present invention.

FIG. 5 is a sectional view showing another embodiment of the flexible printed circuit board according to the present invention.

FIG. 6 is a sectional view showing a conventional flexible printed circuit board.

FIG. 7 is a sectional view showing a conventional flexible printed circuit board.

[Explanation of symbols]

30, 40 ... Flexible printed circuit boards 32, 42 ... Base film (base layer) 36, 46 ... Cover lay (cover layer) 34A, 34B, 34C, 44A, 44B, 44C ... Circuit pattern 38, 48 ... Reinforcing plate 38A, 48A , 48B ... End face

Claims (1)

[Claims] 1. A flexible printed board in which a circuit pattern is sandwiched between a base layer and a cover layer, wherein a reinforcing plate is attached to the base layer, and an end surface of the reinforcing plate is formed into a curved shape. Flexible printed circuit board.