JPH0538934U - Printed wiring board - Google Patents

Abstract

(57) [Summary] [Structure] A hard substrate 4 is attached to the back surface of a flexible insulating film 1 having a printed wiring 2 formed on the front surface. The reinforcing plate 6 that is inclined from the upper end of the substrate 4 to the insulating film 1 is formed of an elastic member. [Effect] At the boundary between the rigid portion 7 and the flexible portion 8, the rigidity of the flexible portion 8 gradually decreases, so that the insulating film 1 can be prevented from being sharply bent. Therefore, it is possible to prevent the circuit from being broken due to the disconnection of the printed wiring 2 and the cracking or peeling of the solder resist 3.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a printed wiring board having both a rigid portion and a flexible portion, and is particularly effective when applied to a printed wiring board formed by using a conductive paste for a wiring pattern.

[0002]

[Prior Art]

 A conventional printed wiring board having both a rigid portion and a flexible portion will be described with reference to FIG. 4 and FIG. 5 showing a soot cross section thereof.

Reference numeral 1 is a bendable insulating film such as polyethylene terephthalate or polyimide. Reference numeral 2 denotes a printed wiring, which is formed on the surface of the insulating film 1 by screen printing or the like using a conductive printing material in which conductive particles such as Ag paste or carbon paste and a binder resin are mixed. Reference numeral 3 is a solder resist formed so as to cover the upper surface of the printed wiring 2, and protects the circuit surface. Reference numeral 4 denotes a substrate such as a glass / epoxy substrate or a phenol substrate, which is laminated and adhered to the back surface of the film 1 with an adhesive 5 or the like.

The flexible wiring board configured as described above has a structure having a rigid portion 7 in which the substrate 4 is attached to the insulating film 1 and a flexible portion 8 that remains as the insulating film 1. Since it can be deformed to any shape, it can be placed on a movable part or a bent part of an electronic device.

[0005]

[Problems to be solved by the device]

 However, in the printed wiring board having the above structure, for example, when the flexible portion 8 is deformed in the direction of arrow A, the insulating film 1 is formed at the boundary line 1a between the rigid portion 7 and the flexible portion 8 as shown in FIG. It may bend sharply.

In such a case, the printed wiring 2 formed on the surface of the film 1 is cracked to cause disconnection, and also the solder resist 3 for protecting the circuit surface and ensuring electrical insulation is used. The circuit will be destroyed by cracks.

The present invention was devised by focusing on such conventional problems. In a printed wiring board having both a rigid portion 7 and a flexible portion 8, stress was applied to the insulating film 1 at the boundary portion. Even in the case, it is an object to provide a printed wiring board in which the insulating film 1 does not bend sharply.

[0008]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the printed wiring board of the present invention has a reinforcing plate formed of an elastic member, which is gradually thinned from the rigid portion to the flexible portion near the boundary between the rigid portion and the flexible portion. is doing.

[0009]

[Action]

 According to the above configuration, the rigidity of the reinforcing plate gradually decreases from the rigid portion to the flexible portion, and excessive pressure is not applied to the insulating film at the boundary portion between the rigid portion and the flexible portion.

[0010]

【Example】

 Hereinafter, a printed wiring board of the present invention will be described in detail with reference to the drawings showing an embodiment thereof. FIG. 1 is a perspective view of a printed wiring board according to an embodiment of the present invention, and FIG. 2 is a sectional view of the same. The same components as those of the conventional one are designated by the same reference numerals, and the description thereof will be omitted. The configurations of different components will be described below.

As shown in FIGS. 1 and 2, on the same surface of the insulating film 1 on which the substrate 4 is formed, a reinforcing plate 6 whose cross-sectional shape is gradually thinned from the upper end of the substrate 4 to the insulating film 1 is provided. Is forming. The reinforcing plate 6 is a member that is more elastic than the substrate 4, and is laminated and bonded adjacent to the substrate 4 with an adhesive 5.

With this structure, the rigidity of the reinforcing plate 6 gradually decreases from the rigid portion 7 toward the boundary line 1 a of the flexible portion 8. Therefore, even when the flexible portion 8 is deformed in the direction of the arrow A, the insulating film 1 does not sharply bend at the boundary line as shown in FIG. 3, so that the printed wiring 2 is prevented from being broken or the circuit being destroyed. You can

At this time, the bending angle when the flexible portion 8 is stressed can be changed by changing the inclination angle and the material of the end portion of the reinforcing plate 6 to change the rigidity of the reinforcing plate 6. Since it is possible, it can be used properly according to the purpose. It is desirable that this bending half diameter be larger than the critical radius at which wire breakage occurs, which is obtained by repeated bending tests.

In the above embodiment, the portion of the substrate 4 may be formed of the same elastic material as the reinforcing plate 6 so that the substrate 4 and the reinforcing plate 6 have an integrated structure. It is also possible to form the insulating film 1 by placing it in a mold and then performing injection molding instead of stacking layers.

[0015]

[Effect of the device]

 As described above, according to the present invention, in a printed wiring board having both a rigid portion and a flexible portion, an elastic material is arranged so that its rigidity becomes gradually smaller near the boundary line between the rigid portion and the flexible portion. However, by making the boundary part flexible, it is possible to prevent abrupt bending of the flexible film part. Therefore, especially when a conductive paste is used for the wiring, it is possible to prevent disconnection of the circuit due to bending. In addition, in the above-mentioned embodiment, when the printed wiring is overcoated, there is an effect of preventing disconnection or destruction of the circuit due to cracking or peeling of the overcoat.

[Brief description of drawings]

FIG. 1 is a perspective view of a printed wiring board according to an embodiment of the present invention.

FIG. 2 is a sectional view of the same printed wiring board.

FIG. 3 is a perspective view showing one usage state of the printed wiring board.

FIG. 4 is a perspective view of a conventional printed wiring board.

FIG. 5 is a sectional view of the same printed wiring board.

FIG. 6 is a perspective view showing one usage state of the printed wiring board.

[Explanation of symbols]

 1 Insulating film 1a Boundary between rigid part and flexible part 2 Printed wiring 3 Solder resist 4 Substrate 5 Adhesive 6 Reinforcement plate 7 Rigid part 8 Flexible part

Claims (2)

[Scope of utility model registration request] 1. A printed circuit board in which printed wiring is formed on the surface of a flexible film, and a substrate harder than the film is partially formed on the back surface of the film,
A printed wiring board, characterized in that a reinforcing plate having a shape such that the thickness thereof is thinned from the upper end of the substrate formed on the film to the film is formed of an elastic member. 2. The printed wiring board according to claim 1, wherein the substrate and the reinforcing substrate are integrally formed of the same member.