JPS58132987A - Printed circuit board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printed wiring board constructed by combining a flexible printed wiring board and a hard reinforcing board, and in particular, prevents disconnection of narrow copper foil patterns in the flexible part and improves flexibility. Our objective is to provide printed wiring boards with excellent features, high reliability, and excellent workability and serviceability.

Printed wiring circuits are becoming larger and more complex as the components used become smaller and more densely packaged, and the number of input/output terminals is also increasing significantly. Therefore, the connection of printed wiring circuit boards to each other or to other parts or devices has become one of the important issues in printed wiring circuit technology. Furthermore, flexible printed wiring boards are being used for these connections. First, the configuration of the conventional example will be described. As shown in FIG. 1A, a rigid printed wiring board 1 is generally made of a substrate made of paper, phenol laminate, etc., on which a copper foil pattern 2 is appropriately formed. ) 1a, a hard printed wiring board removal part 1b, a perforation 1c, a dividing recess 1d, and a holding hole 1e. As will be described in detail later, in the final state, this hard printed wiring 1 is divided into a main wiring board 1 aa , an auxiliary wiring board 1 bb , and a holding plate I OC for use. FIG. 1B is a sectional view taken along the line AA' in FIG. 1A, and 3 is a solder resist which is a protective film.

FIG. 2A shows a front view of the flexible printed wiring board. The flexible printed wiring board 11 is generally a board made of a plastic film or the like with a copper foil pattern 12 appropriately formed thereon. FIG. 2B is a cross-sectional view taken along the line B-B' in FIG. It is formed to cover almost the entire area except for the land portion. The structure of the flexible printed wiring board 11 has outstanding characteristics that can guarantee a lifespan that can withstand bending tens of thousands to millions of times, but it has the disadvantage that it cannot be designed to mount heavy components or heat-generating components. Therefore, in order to solve the above-mentioned drawbacks of flexible printed wiring boards, printed wiring boards constructed by combining a hard reinforcing board and a flexible printed wiring board have been increasingly used recently. A conventional example in which the rigid reinforcing plate is composed of a rigid printed wiring board will be described with reference to FIG. Note that the same parts as in FIGS. 1 and 2 are given the same numbers and their explanations will be omitted. Figure 3A
I-j: A front view of a state in which adhesive 3o is applied to the substrate side of the rigid printed wiring board 1 in FIG. 1 and the substrate side of the flexible printed wiring board 11 in FIG. 2, and both wiring boards 1 and 11 are pasted; FIG. 3B is a sectional view taken along the line C-σ of FIG. 3A. In the rigid printed wiring board removal section 1b, the flexible printed wiring board 11
The printed wiring board has a configuration of only X1. Even at the end with the auxiliary wiring board 1 bb, the abutting end X of both boards 1 and 11
2 in a straight line. Although not shown in the drawings, the combined part of the rigid printed wiring board 1 and the flexible printed wiring board 11 has the advantage that any parts can be attached to it, and the electrical connection between the main wiring board 1 aa and the auxiliary wiring board 1 bb is possible. This is done by the copper foil pattern 12 formed on the flexible printed wiring board 11. However, according to such a connection structure, when the flexible printed wiring board 11 is bent in the directions indicated by arrows A and B in FIG. Due to the concentration of stress caused by the bending, minute cracks and breaks are likely to occur on the copper foil pattern 12. Especially when bending in the direction of arrow B, cracks can easily grow and grow due to several bends due to extremely fluffy waste. Breakage of the copper foil pattern 12 often occurs. At this time, it goes without saying that the narrower the copper foil pattern portion is, the more likely it is to break. Using the bending stress in directions A and B at all is important from the standpoint of design and structure to take advantage of the advantages of flexible printed wiring boards, and also in the production process, after all mounted components are inserted into printed wiring boards, soldering is not required. The work will be done,
This was also made impossible because it was then divided into parts and reassembled. And once a small crack has appeared,
Although illustration is omitted because there is a risk of causing defects such as disconnection of the copper foil pattern depending on the subsequent usage conditions, as a method to solve the above-mentioned defect, the abutting end of the flexible printed wiring board and the rigid reinforcing plate The method used was to fill the area with a reinforcing circumferential plate (vinyl tape, etc.) or silicone rubber as a viscoelastic material. However, this method has many drawbacks and problems, such as requiring many independent parts and materials to prevent breakage of the copper foil pattern and having extremely poor workability.

This invention solves the above-mentioned conventional drawbacks, improves the shape of the narrow copper foil pattern part and the hard reinforcing plate part formed on the flexible part, and eliminates the need to add special parts or operations to the abutment end. This is intended to prevent cracks and disconnection defects in the copper foil pattern of the flexible printed wiring board due to bending of the flexible printed wiring board in the vicinity of the flexible printed wiring board.

The basic technical idea of the present invention is to increase the length of the abutting end of the flexible printed wiring board and the hard reinforcing plate part, where bending stress is concentrated, by forming an uneven curve instead of making it a straight line. The abutting end of the narrow copper foil pattern formed on the flexible printed wiring board and the hard reinforcing plate has a concave structure on the side where the hard reinforcing plate is attached from the other abutting end.

An embodiment of the present invention will be described below with reference to FIGS. 4 and 5. Only the points that are different from the conventional example shown in FIG. 3A are shown in the main configuration diagram and will be described in detail below.

FIG. 4A is a back view showing the configuration of the main parts, and the rigid printed wiring board 10 serving as the rigid reinforcing plate has slits 1 and 10 as in the conventional example.
a (not shown), hard printed wiring board removal part 1ob, perforation 1C1 dividing concave part 1dK, it has a shape that can be divided into main wiring board 10aa, auxiliary wiring board 10bb, and holding plate 1oa. The flexible printed wiring board 11 and the copper foil pattern 12 are the same as those in the conventional example shown in FIG. The major difference from the conventional example is that the shape of the rigid printed wiring board removal section 10b is such that the abutting end X11. The point that X12 is not a straight line but an uneven curve, and the flexible printed wiring board 11
The upper narrow copper foil pattern 12 is a hard stamp on the wiring board 1.
The main wiring board 10aa and the auxiliary wiring board 10bb of the rigid printed wiring board 10 form contact end recesses X'111 and X'12 at the portions where they intersect with Q. Fourth
Figure B is a front view of essential parts of the embodiment. Here, illustrations of mounting electronic component 9 component insertion holes, soldering lands, etc. are omitted.

By having the above-described configuration, after electronic components (not shown) are attached, the flexible portion of the flexible printed wiring board 11 located in the hard printed wiring board removal section 10b is bent and used by incorporating it into general consumer equipment. Even if the contact ends of both printed wiring boards 10 and 11 X11. The concentrated bending stress is no longer applied to X12 and is dispersed near the abutting end. Furthermore, no matter which direction the flexible printed wiring board 11 is bent, the bending stress is applied only to the wide part of the copper foil pattern 12 or to the part of the board without the copper foil pattern 12, which causes cracks in the narrow copper foil pattern part. It is possible to prevent the possibility of occurrence of breakage or breakage defects. Further, it is possible to prevent disconnection of the copper foil pattern without requiring independent parts or materials such as a reinforcing patch plate or a viscoelastic material used in the conventional example.

FIGS. 5A and 5B show other embodiments of the present invention. OA is a back view showing the main structure, and FIG. 5B is a front view of the same.

The shape of the hard printed wiring board removal section 2ob is different from that in the embodiment shown in FIG. The hard printed wiring board 2o serving as a hard reinforcing plate has a slit 1a (not shown), a hard printed wiring board removal part 20b, a perforation 1c, and a dividing recess 1d.
The shape is such that it can be divided into a main wiring board 20aa, an auxiliary wiring board 20bb, and a holding plate 2occ. And flexible printed wiring board 11 and both boards 20aa, 20bb
In the configuration of the abutting end X21°X22, the portion other than the vicinity of the narrow copper foil pattern 12 is formed into the abutting end convex portion X'21.
They are formed to protrude from the main wiring board 2 oaa and the auxiliary wiring board 2 obb, respectively, at an angle of X'2°. Although there is a difference in that this embodiment has the advantage of having a larger mounting area for various electronic components than the embodiment shown in FIG. 4, it goes without saying that almost the same effects and actions can be obtained. In addition, in the configuration of the abutting ends X211X22 of both plates 11 and 20, a copper foil pattern is designed such that the length of the abutting end in the narrow copper foil pattern part is smaller than the length of other abutting parts. This will further enhance the implementation effects and effects of the present invention.

In both of the above embodiments, a hard printed wiring board is used as the hard reinforcing plate, but the present invention is also applicable to a case where a hard insulating board is simply used.

Furthermore, it is also conceivable to use it in combination with the use of reinforcing plates, viscoelastic materials, etc. used in the conventional example.

As is clear from the above description, the printed wiring board of the present invention does not make the equivalent ends of the hard reinforcing board part and the flexible printed wiring board part straight, but rather the abutting end of the drawing board when the uneven curved printed wiring board part is bent. The force acting on the printed wiring board is significantly relaxed, and therefore there is no risk of breakage of the copper foil pattern due to cracks occurring on the copper foil pattern on the printed wiring board, and it has excellent flexibility. Highly reliable and workable.

The present invention realizes mass production of inexpensive printed wiring boards with excellent serviceability, and its practical effects are extremely large.

[Brief explanation of the drawing]

FIG. 1 shows the structure of a conventional rigid printed wiring board related to the present invention, A is a front view, B is a sectional view, and FIG. 2 is a flexible printed wiring board. 3B is a front view, B is a sectional view, FIG. 3A is a front view of a conventional printed wiring board, B is a sectional view, and FIG. 4 is a main part configuration of a printed wiring board in an embodiment of the present invention. A is a back view, B is a front view, and FIG. 6 shows a main part configuration of another embodiment of the present invention, A is a back view, and B is a front view. 1o 2o... Rigid printed wiring board, 10aa. 20aa... Main wiring board, 10bb, 20bb.
...Auxiliary wiring board, 10cc, 20cc...
・Holding plate, 11...Flexible printed wiring board,
12...Copper foil pattern, X11. X12. X2
1. X22...Abutting end of both plates, X'11. X
'12...Concave portion at the contact end of both plates, x', x'
...Protrusion at the contact end of both plates. 21 22 Name of agent Patent attorney Toshio Nakao and one other famous person
2 figure

Claims (1)

[Scope of Claims] O) A flexible board is provided with a copper foil pattern forming a circuit, and a hard reinforcing plate is attached thereto, and a flexible portion consisting only of a flexible printed wiring board without the hard reinforcing board is provided on the flexible board, and the above-mentioned The abutting end of the narrow copper foil pattern formed on the flexible part and the hard reinforcing plate is configured with a concave portion closer to the hard reinforcing plate pasting side than the abutting end of the other flexible printed wiring board part and the hard reinforcing plate. A printed wiring board characterized by: (2) Claim 1, characterized in that the length of the abutting end of the narrow copper foil pattern portion and the hard reinforcing plate is smaller than the length of the other abutting end of both plates. Printed wiring board as described.