JP2003324256A - Flexible printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible printed wiring board in which the generation of dust from a reinforcing board is restrained without performing chemical etching. <P>SOLUTION: On both surfaces of connector insertion parts A positioned on both ends of a flexible printed wiring board 1 and both surfaces of a part mounting part B positioned on an intermediate part of the board 1, a reinforcing board 2 whose working end surface is coated with a resin coating 3 is stuck, respectively, with an adhesive agent 4. By applying the resin coating to the cut end surface, the peel-off and fall-out of a small piece of a material from the end surface are restrained. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible printed wiring board having a reinforcing plate adhered to a required portion. In particular, the present invention relates to a flexible printed wiring board capable of preventing generation of dust from a reinforcing plate. 2. Description of the Related Art A flexible printed wiring board uses a rigid board because its flexibility (flexibility) is suitable for wiring of a driving section and there is a degree of freedom in wiring. More functional than wiring. Therefore, it is generally used as internal wiring of small electronic devices. [0003] However, in a portion requiring rigidity because of its flexibility, for example, in a portion to be inserted into a connector, a component mounting portion, or a portion requiring mechanical fixation, a reinforcing plate made of a hard material is used. Are integrated by bonding with an adhesive. Conventionally, a material such as a glass epoxy plate, an aluminum plate, or a polyimide film is used for the reinforcing plate. [0004] These reinforcing plates are used after being cut and punched into a shape suitable for the application.
When a physical method is used for cutting, the state of the processing end surface is not controlled at all. For this reason, the material of the reinforcing plate may be separated into small pieces from the end face and fall off. And the small piece of the end surface of the reinforcing plate generated in this way becomes dust. In small precision electronic devices such as a hard disk drive (HDD) and a mobile phone, dust generated from the reinforcing plate becomes a foreign substance, which adversely affects micro bonding, component mounting, sliding characteristics, etc. of a flexible printed wiring board. A problem has arisen. On the other hand, if chemical etching is used for cutting the reinforcing plate, the generation of dust as described above can be suppressed. However, there are materials for the reinforcing plate to which chemical etching cannot be applied. Further, when chemical etching is used, there is also a problem that processing cost is increased. [0007] Therefore, a main object of the present invention is to provide a flexible printed wiring board capable of suppressing generation of dust from a reinforcing plate without performing chemical etching. [0008] The present invention is to prevent a small piece of material from falling off the end face by applying a resin coating to the processed end face of the reinforcing plate. That is, the present invention is a flexible printed wiring board in which a reinforcing board is attached to a flexible printed wiring board, wherein the reinforcing board is provided with a resin coating on an outer surface subjected to a cutting process. . When a reinforcing plate is adhered to a required portion of a flexible printed wiring board, if the reinforcing plate is processed by physical cutting using a blade or the like, small pieces of the material of the reinforcing plate fall off the processed end face and the wiring board is cut off. Had various problems. In view of the above, according to the present invention, a resin coating is applied to a processed end surface that has been subjected to a physical cutting process, thereby preventing peeling and falling off of a small piece of material. In the present invention, the resin coating applied to the reinforcing plate needs to protect the cut end face of the reinforcing plate, and the coating method is not particularly limited. For example, various methods such as dip coating, spray coating, and screen coating can be adopted. When coating is performed, it is preferable to support a portion other than the cut end surface that does not require coating, that is, the joint surface of the reinforcing plate with the flexible printed wiring board and the opposing surface thereof. For example, as shown in FIG. 2, the front surface (joining surface with the flexible printed wiring board) 11A of the reinforcing plate 11 and the back surface (opposite surface of the joining surface) 11B are sandwiched by a jig 12, and the cut end face 11C is placed in the resin solution 13. How to immerse
(Dip coat). As another method, as shown in FIG. 3, the reinforcing plate 11 is arranged on the turntable 14 so that either of the front and back surfaces is in contact with the turntable 14, and the resin is injected by the spray nozzle 15 while rotating the turntable 14. Method (spray coat). As another method, as shown in FIG. 4, the reinforcing plate 11 is arranged on the work table 16 so that one of the front and back surfaces is in contact with the work table 16, and the resin 18 placed on the mesh sheet 17 is dropped by a squeegee 19. A method (screen coating) of applying one end face 11C and applying the other end face 11C with a return squeegee 19 may be used. In this method, the mesh sheet 17 is previously set so that the cut end surface 11C of the reinforcing plate 11 can be coated with resin.
First, patterning adapted to the cut end face 11C is performed. As the material to be coated, various materials such as polyurethane, epoxy, polyimide, acrylic, or a mixture thereof can be applied. The thickness of the coating is not particularly limited, but if it is too thin, it is difficult to obtain the effect of preventing detachment of small pieces, and if it is too thick, unnecessary properties are given. Therefore, the thickness is preferably 3 μm or more and 30 μm or less, particularly 5 μm or more and 15 μm or less. The material of the reinforcing plate is preferably a glass epoxy plate, an aluminum plate, a polyimide plate or the like, and may be appropriately selected according to the application. These reinforcing plates may be subjected to a pretreatment for improving the adhesiveness of the resin before applying the resin coating. Such pretreatment includes, for example, washing with an acid or alkali, treatment with a silane coupling agent, and the like. Further, it is preferable to apply the adhesive for bonding the reinforcing plate to the flexible printed wiring board after resin coating. This is because it is generally difficult to perform resin coating after applying the adhesive, and there is a possibility that the performance of the adhesive may be impaired. Embodiments of the present invention will be described below. FIG. 1 is a schematic sectional view showing an example of the flexible printed wiring board of the present invention. The flexible printed wiring board 1 of the present invention has both sides of the connector insertion portion A located at both ends,
On both surfaces of the component mounting portion B located in the middle, a reinforcing plate 2 having a resin coating 3 applied to a processed end surface is adhered. In this embodiment, the reinforcing plate 2 is made of a glass epoxy plate, and is formed into a desired shape by cutting using a blade. A polyurethane coating is applied to the processed end face. The coating was performed by dip coating shown in FIG. 2, and the coating thickness was 10 μm. In this example,
After applying the polyurethane coating 3, the reinforcing plate 2 is joined to the flexible printed wiring board 1 by the adhesive 4. In this example, the reinforcing plates 2 are joined to both sides of the flexible printed wiring board 1, but may be provided on only one side. With this configuration, the flexible printed wiring board of the present invention can effectively prevent and prevent the generation of dust of the small material pieces peeled from the processing end surface of the reinforcing plate. Therefore, the flexible printed wiring board of the present invention does not cause problems in micro joining, component mounting, sliding characteristics, and the like. As described above, according to the flexible printed wiring board of the present invention, there is an excellent effect that it is possible to suppress and prevent the detachment and detachment of the small material pieces from the cut end face of the reinforcing plate. obtain. That is, the present invention makes it possible to eliminate the generation of foreign matter on the flexible printed wiring board, and does not adversely affect the characteristics of precision electronic devices. Further, the present invention can be applied to various reinforcing plates because the generation of dust is suppressed by applying a resin coating to the cut end surface of the reinforcing plate instead of the chemical etching. Further, the manufacturing cost can be reduced as compared with the chemical etching.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic sectional view showing an example of the flexible printed wiring board of the present invention. FIG. 2 is a schematic explanatory view showing a resin coating method of a reinforcing plate, showing a dip coating. FIG. 3 is a schematic explanatory view showing a method for coating a reinforcing plate with a resin, showing spray coating. FIG. 4 is a schematic explanatory view showing a method of coating a reinforcing plate with a resin, showing a screen coating. [Description of Signs] 1 Flexible Printed Wiring Board 2 Reinforcement Plate with Resin Coating 3 Coating 4 Adhesive 11 Reinforcement Plate 11A Surface 11B Backside 11C Cutting End Face 12 Jig 13 Resin Solution 14 Turntable 15 Spray Nozzle 16 Worktable 17 Mesh sheet 18 Resin 19 Squeegee

Claims (1)

Claims 1. A flexible printed wiring board comprising a flexible printed wiring board and a reinforcing plate adhered to the flexible printed wiring board, wherein the reinforcing plate has a resin coating applied to an outer surface which has been cut. A flexible printed wiring board.