JP2005109355A - Discharge path forming structure of flexible printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a discharging path in a flexible printed wiring board, in order to prevent previously a static electricity received by the flexible printed wiring board from so flowing through the printed wiring board having mounted electronic components as to destroy the electronic components. <P>SOLUTION: In the flexible printed wiring board FPC, there are so arranged in parallel with each other a plurality of conductive lines L1, L2 made of metal foils as to form their end portions as connective terminals. Further, there is formed a window FPC-W for exposing to the external a portion of the grounding conductive line L2 interposed between the connective terminals of the flexible printed wiring board FPC, and the grounding conductive line L2 facing the window FPC-W is so connected with a grounding line as to form a discharging path. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a discharge path forming structure of a flexible printed wiring board that can effectively eliminate static electricity that affects electronic components and the like generated in precision electronic equipment and the like.

  In general, precision electronic devices such as computers and audiovisual devices are configured with a printed wiring board (hereinafter referred to as PCBA) on which electronic components such as semiconductor integrated circuit elements are mounted, and signal processing, data processing, Input / output control and the like are performed with weak signals. Further, in the case of electrically connecting a plurality of PCBAs that are separated inside the apparatus, a flexible printed wiring board (hereinafter referred to as FPC) is usually used.

  FIG. 5 shows a disk device for driving an optical disk constructed using such PCBA and FPC. In order to facilitate understanding of the present invention, an outline of the structure of the device will be described below. To do.

  In the figure, reference numeral 1 denotes a disc tray integrally formed of synthetic resin, and a turntable 2 located at the center is fixed to a drive shaft of a spindle motor 3 built in the disc tray 1. The center hole of the optical disc is clamped and rotated by the clamp head 4 that is integrally constructed. The head unit 5 mainly composed of an optical pickup moves in the radial direction in the slit 1a formed in the disc tray 1 and records / reproduces information on / from the optical disc. The disc tray 1 configured as described above is configured to be supported by the guide rail 6 and fit in the chassis case 7.

  The chassis case 7 includes a bottom chassis 7a and a cover chassis 7b, and the disk tray 1 moves forward and backward through an integrally formed internal space. PCBA1 is disposed on the back side of the bottom chassis 7a, and PCBA2 is disposed on the back surface of the disc tray 1. The PCBA 1 is mounted with an electronic component P such as a semiconductor integrated circuit element that performs data processing with a weak signal obtained by recording / reproducing with an optical disk, and the PCBA 2 is mainly incorporated in the disk tray 1. Electronic components such as a semiconductor integrated circuit element for servo-controlling drive systems such as the spindle motor 3 and the head unit 5 and a semiconductor integrated circuit element for recording / reproducing data on / from an optical disk are mounted.

  The PCBA1 and PCBA2 are mounted with multi-connectors MC1 and MC2, and the multi-connectors MC1 and MC2 are connected to the connection terminals at the ends of the FPCs. The PCBA1 and PCBA2 are electrically bridged by the FPC. Thus, signals can be exchanged between PCBA1 and PCBA2. The end connected to the multi-connector MC2 of the FPC is flexible so that it can follow the movement of the disc tray 1, but the other parts are fixed to the bottom surface of the bottom chassis 7a with an adhesive or double-sided adhesive tape. ing.

The FPC is roughly divided into a signal line L1 and a ground line L2 as shown in FIG. The signal line L1 is connected to the electronic component P mounted on the PCBA1 through the multi-connector MC1, while the ground line L2 is connected to the ground line E of the PCBA1 through the multi-connector MC1. The line E is connected to the bottom chassis 7a via the fixing screw 8 of PCBA1, and is connected to the system ground circuit. (For example, patent document 1).
Japanese Patent Application No. 2002-318324

  As described above, the FPC is usually employed in many cases when bridging between separated PCBAs, and is suitable for bridging the fixed portion and the movable portion as in the disk device described above. By the way, in the case of the disk device, the PCBA 2 disposed on the disk tray which is a movable part is driven by a relatively large current in order to servo-control the drive system, but the PCBA 1 fixed to the bottom chassis 7a. However, since data signal processing is mainly performed, weak signal processing is likely to be affected by static electricity, and the mounted electronic components are destroyed.

  In particular, in the case of a disk device, static electricity flows from the movable part to the PCBA 1 through the FPC when a human finger touches the metal part of the disk tray, which is the movable part, and further flows from the ground line to the signal line on the PCBA 1. There is a case where static electricity passes through the FPC again and enters the total of PCBA2 and destroys the pickup or the like. FIG. 6 shows the effect on PCBA1 when static electricity C flows into the FPC. The static electricity C flowing into PCBA1 flows through the earth line E, but part of it flows into the electronic component P, and the electronic component P itself. Or the data being processed will be destroyed.

  As a simple solution to such a problem, as shown in FIG. 7, the ground line L2 of the FPC is brought into contact with the bottom chassis 7a so that the static electricity C flows directly to the ground circuit of the system and does not flow into the PCBA1. . Therefore, as shown in the figure, a part of the ground line L2 of the FPC is fixed to the bottom chassis with screws 9, and the bottom chassis 7a and the ground line L2 are short-circuited. Therefore, the bottom plate of the disk tray 1 comes into contact with the head, which causes a mechanical problem. In order to avoid this, the thickness of the entire disk device is increased. However, since the disk device is made thinner, it is a large design change and cannot be realized realistically.

  In addition, when the FPC is mechanically electrically connected by screwing, it is necessary to perform a special shape treatment on the FPC as disclosed in, for example, Japanese Patent Laid-Open No. 8-203580 in order to improve the conduction performance. There is a problem that the manufacturing cost of the FPC is increased.

  Therefore, the present invention solves the above problems by means described below. That is, the invention according to claim 1 is a flexible printed wiring board in which a plurality of conductive paths made of metal foil are arranged in parallel and end portions are formed as connection terminals. A window hole for exposing a part of the grounding conductive path between the connection terminals of the substrate is formed, and the grounding conductive path facing the window hole is connected to the grounding path.

  According to a second aspect of the present invention, in the first aspect of the present invention, the grounding conductive path of the window hole is connected to the grounding path by a conductive adhesive.

  According to a third aspect of the present invention, in the first aspect of the present invention, the grounding conductive path of the window hole is connected to the grounding path by a conductive double-sided adhesive tape.

  According to a fourth aspect of the present invention, in the first aspect of the present invention, the grounding conductive path of the window hole is subjected to solder plating, and the solder plating is connected to the grounding path.

  According to the present invention, since the grounding conductive path of the FPC can be connected to the grounding path of the apparatus while the FPC is fixed in the same manner as in the prior art, a structural problem for the apparatus does not occur. In addition, since the connection structure can be simplified without the need for fixed parts or the like, the cost can be improved and the assembly work can be facilitated.

  The present invention is suitable when implemented in a wiring structure that connects FPC and PCBA, and can protect electronic components from harmful static electricity and improve the reliability of the apparatus.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected and demonstrated to the structure same as the past.

  FIG. 1 is a perspective view showing the main part of the first embodiment of the present invention. In FIG. 1, the FPC connected to the multi-connector MC1 of PCBA1 exposes the ground line L2 on the back surface thereof. A window hole FPC-W is formed. That is, as shown in FIG. 2, the FPC normally has a metal foil conductive path sealed in a laminated state by an insulating base film F1 and a protective film F2. By forming the window hole FPC-W at one or a plurality of arbitrarily defined locations, the insulation state of this portion is removed. Note that the window hole FPC-W may be formed in the manufacturing process of the entire FPC, or the base film F1 may be peeled off after completion of the FPC.

  Next, as shown in FIG. 2A, the conductive adhesive G1 is applied to the window hole FPC-W in which the FPC is formed as described above, and the base film F1 is bottomed with the adhesive or the double-sided adhesive tape S. Adhere to the chassis 7a. As a result, the conductive adhesive G1 is bonded to the bottom chassis 7a as shown in FIG. 2B, so that an electric circuit from the ground line L2 to the bottom chassis 7a is formed, and the static electricity received by the FPC is generated by the bottom chassis 7a. Can lead to.

  In the second embodiment of the present invention, the conductive double-sided adhesive tape G2 is used for attaching the FPC. When the FPC is attached on the bottom chassis 7a as shown in FIG. 3, the window hole FPC- An electric circuit is formed from the W portion ground line L2 to the bottom chassis 7a, and the static electricity received by the FPC can be guided to the bottom chassis.

  In the third embodiment of the present invention, as shown in FIG. 4A, a solder plating G3 is applied to the ground line L2 exposed in advance to the FPC window hole FPC-W, and the base fill F1 is formed with an adhesive or a double-sided adhesive tape S. Is attached to the bottom chassis 7a. As a result, as shown in FIG. 4B, the solder plating G3 contacts the bottom chassis 7a, so that an electric circuit from the ground line L2 to the bottom chassis 7a is formed, and the static electricity received by the FPC is guided to the bottom chassis 7a. Can do.

It is a principal part perspective view of the implementation state of 1st Example of this invention. It is sectional drawing for demonstrating 1st Example of this invention. It is sectional drawing for demonstrating 2nd Example of this invention. It is sectional drawing for demonstrating 3rd Example of this invention. It is a perspective view for demonstrating the structure of a disc apparatus. It is a top view for demonstrating the conventional malfunction. It is a top view for demonstrating the example of a solution of the conventional malfunction.

Explanation of symbols

FPC ... Flexible printed circuit board L1 ... Signal line L2 ... Ground line F1 ... Base film F2 ...・ Protective film PCBA1 ... Printed wiring board PCBA2 ... Printed wiring board MC1 ... Multi connector MC2 ... Multi connector 7 ... Chassis case 7a・ ・ ・ ・ ・ ・ Bottom chassis 7b ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Cover chassis

Claims (4)

A flexible printed wiring board in which a plurality of conductive paths made of metal foil are arranged in parallel and end portions are formed as connection terminals, and a conductive path for grounding between the connection terminals of the flexible printed wiring board A discharge path forming structure for a flexible printed circuit board, wherein a window hole for exposing a part of the window is formed, and a grounding conductive path facing the window hole is connected to the ground path. 2. The discharge path forming structure for a flexible printed wiring board according to claim 1, wherein the grounding conductive path of the window hole is connected to the ground path by a conductive adhesive. 2. A discharge path forming structure for a flexible printed wiring board according to claim 1, wherein the grounding conductive path of the window hole is connected to the ground path by a conductive double-sided adhesive tape. 2. The discharge path forming structure for a flexible printed wiring board according to claim 1, wherein the grounding conductive path of the window hole is subjected to solder plating, and the solder plating is connected to the ground path.

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