JP3859527B2 - Flexible printed wiring board layout structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an arrangement structure of a flexible printed wiring board (FPC). In particular, the present invention relates to an FPC arrangement structure that can reduce the probability of conductor disconnection even when repeated bending is applied.
[0002]
[Prior art]
In recent years, the development of mobile phones has been remarkable. In particular, taking into account the increased screen size, compactness, fashionability, and protection of operation buttons, mobile phones with two-fold type (shell type) have become mainstream recently, and this trend will continue in the future. Expected to continue.
[0003]
FIG. 5 (A) is a schematic diagram of a state in which a shell-type mobile phone is opened, FIG. 5 (C) is a schematic diagram of a closed state, and FIG. 5 (B) is a schematic diagram of an FPC in a state of opening the mobile phone. (D) is a schematic diagram of the FPC in the closed state. The shell-type mobile phone 60 has a structure in which a display unit 62 such as a liquid crystal screen is foldably connected by a hinge 63 to a key switch unit 61 in which operation buttons (not shown) are arranged. The key switch unit 61 and the display unit 62 are electrically connected via the FPC 64.
[0004]
For example, as shown in FIG. 4, the FPC used here has an offset type shape in which straight portions 50 at both ends are connected by an S-shaped bent portion 51, and the S-shaped bent portion 51 is wound once in the hinge. Thus, folding resistance when the key switch part and the display part are repeatedly bent is obtained.
[0005]
At that time, the bent portion of the FPC is disposed in the cylindrical member of the hinge, but conventionally no special configuration for maintaining the wound shape of the wound FPC has been provided.
[0006]
[Problems to be solved by the invention]
However, the FPC arrangement structure as described above has a problem that the winding diameter of the FPC becomes excessively small as the display unit and the key switch unit are opened and closed. The conventional FPC arrangement structure is not provided with any means for maintaining the wound shape of the wound FPC. For this reason, when the mobile phone is repeatedly opened and closed, as shown in FIG. 5D, the winding diameter may be reduced or the winding shape may be crushed. As a result, poor conduction and disconnection of the conductor occur, and in some cases, FPC breaks.
[0007]
Accordingly, a main object of the present invention is to provide an FPC arrangement structure capable of suppressing conductor disconnection and FPC breakage in a bent FPC.
[0008]
[Means for Solving the Problems]
The present invention achieves the above object by providing a shape-retaining means for the FPC that is bent and arranged.
[0009]
That is, the arrangement structure of the flexible printed wiring board of the present invention is an arrangement structure of a flexible printed wiring board in which a part of the flexible printed wiring board is bent and arranged at a place where repeated bending acts. A support material having a cylindrical surface is arranged inside the bent portion.
[0010]
By disposing a support material inside the bent part of the FPC, the bent part of the FPC is prevented from being crushed and broken, and the conductor breakage and FPC breakage are suppressed.
[0011]
The shape of the support material only needs to have a cylindrical surface. In general, a pipe-shaped one is suitable. In particular, a cylindrical member in which a part of the peripheral surface is notched in the axial direction is preferable because elasticity in the diameter reducing direction of the support material itself is obtained.
[0012]
The material of the support material is preferably plastic or metal. For example, polyethylene, polypropylene, polyethylene terephthalate, aluminum, and copper can be used. Of course, not only these materials but also laminated and composite materials can be used.
[0013]
Although the thickness of the support material depends on the material, it is generally preferably about 0.2 to 1.0 mm.
[0014]
As for the arrangement of the support material and the FPC, the FPC is preferably wrapped around or attached to the support material. And fixing a support material and FPC with an adhesive agent, or providing an engaging part in a support material and inserting FPC in this engaging part, etc. are mentioned. When an adhesive is used, the support material and the FPC may be bonded entirely or partially.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
Example 1
As shown in FIG. 4, the FPC used in the arrangement structure of the present invention has an offset type shape in which straight portions at both ends are connected by S-shaped bent portions as shown in FIG. In general, such an FPC has connection electrode portions (not shown) connected to a counterpart substrate at both ends. Conductors other than the connection electrode portion are sandwiched between resin films such as polyimide to constitute an FPC. In this example, a conductor is composed of a copper foil having a thickness of 18 μm, and the conductor is sandwiched between a polyimide upper surface resin film and a lower surface resin film each having a thickness of 12.5 μm.
[0016]
Such an FPC and a support material are shown in FIG. Here, a polyethylene pipe 20 in which a part of the peripheral surface is cut out in the axial direction is used as a support material. As shown in FIG. 1 (B), the FPC 10 is wound around the outer periphery of the polyethylene pipe 20 once. The number of windings is not particularly limited. Here, the FPC is simply wrapped around the support material and is not bonded.
[0017]
Such a support material and FPC are used by being disposed in the hinge portion of a shell-type mobile phone, for example.
[0018]
Repeated bending tests were performed using the FPC and support material thus configured. As a comparison, the same bending test was performed on an arrangement structure in which only the FPC was wound once without a support material. The test conditions are as follows.
The FPC is mounted on the actual shell type mobile phone, and the key switch unit and the display unit are repeatedly opened and closed. Here, the opening / closing operation was repeated in a cycle of 2 seconds between “fully open” and “closed”. The inner diameter of FPC is about 5mmφ.
[0019]
As a result, in the FPC arrangement structure using the support material, no conductor breakage or FPC breakage was observed after repeated bending of 100,000 times. In contrast, the FPC arrangement structure without a support material showed conductor breakage after repeated bending of 80,000 times.
[0020]
(Example 2)
In Example 1 described above, the FPC is wound once on the support material. However, as shown in FIG. 2, it may be wound 0.5 times. Thus, even with an arrangement structure in which the FPC 10 is wound around the pipe 20 by 0.5 turns, the bent shape of the FPC can be prevented from being reduced as in the first embodiment, and the conductor disconnection can be suppressed.
[0021]
Example 3
Further, as shown in FIG. 3, an arrangement structure may be employed in which the FPC 10 is waved along the cylindrical support member 30. Even with such an arrangement structure, it is possible to prevent the bent shape of the FPC from being reduced as in the first embodiment, and it is possible to suppress conductor disconnection.
[0022]
【The invention's effect】
As described above, according to the present invention, by arranging a support material at the bent portion of the FPC, the bent portion of the FPC can be retained, and the conductor disconnection and the FPC fracture probability against repeated bending. Can be reduced.
[Brief description of the drawings]
FIG. 1A is an explanatory view showing a state before an FPC is wound around a support material, and FIG. 1B is an explanatory view of the arrangement structure of the present invention showing a state after the FPC is wound around a support material.
FIG. 2 is an explanatory diagram of an arrangement according to the present invention in which FPC is wound around a support member half a turn.
FIG. 3 is an explanatory view of an arrangement structure according to the present invention in which FPC is waved on a support material.
FIG. 4 is a schematic explanatory view of a conventional FPC.
FIGS. 5A and 5B are explanatory diagrams showing changes in the shape of an FPC bent portion in a mobile phone, wherein FIG. 5A is a schematic diagram of a shell-type mobile phone opened, and FIG. 5C is a schematic diagram of a closed state; B) is a schematic diagram of the FPC in a state where the mobile phone is opened, and (D) is a schematic diagram of the FPC in a state where the mobile phone is closed.
[Explanation of symbols]
10 FPC 20 Pipe 30 Support member 50 Straight part 51 Bent part
60 Mobile phone 61 Key switch 62 Display 63 Hinge 64 FPC

Claims (2)

It is an arrangement structure of a flexible printed wiring board in which a part of the flexible printed wiring board is bent at a place where repeated bending acts,
An arrangement structure of a flexible printed wiring board, wherein a bent portion is formed by winding the flexible printed wiring board at least once on a cylindrical support member having a part of the peripheral surface cut in the axial direction .   The flexible printed wiring board arrangement structure according to claim 1, wherein the support member is made of plastic.

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