JPS58140187A - Printed circuit board device - 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 device constructed by combining a flexible printed wiring board and a hard reinforcing board, and in particular prevents disconnection of narrow copper foil patterns in flexible parts and improves flexibility. It has excellent features, high reliability and workability,
The purpose is to provide a printed wiring board device with excellent serviceability.

Printed wiring circuits have become larger and more complex due to the miniaturization of components used in high-density mounting designs, and the number of input/output terminals has also increased significantly. Therefore, the connection between printed wiring circuit boards or between printed wiring circuit boards and other components or devices has become one of the important issues in printed wiring circuit technology. Today, flexible printed wiring boards are used for these connections. First, the configuration of the conventional example will be described. As shown in FIG. 1, the rigid printed wiring board 1 is generally made of paper or a phenol laminate board, on which copper foil and strips 2 are suitably formed, and then processed with a punching die to form a plurality of slits 1a. , hard printed wiring board removal part 1b, perforation 1C1 division recess 1d, holding hole 1e
It constitutes.

As will be explained in detail later, in the final assembled state, this rigid printed wiring board 1 includes a main wiring board 1aa, an auxiliary wiring board 1bb, and a holding plate 1cc.
They are divided into two parts and used separately. FIG. 1B is a sectional view taken along the line A-A' of FIG. 1, and 3 is a solder resist which is a protective film.

FIG. 2 shows a front view of the flexible printed wiring board. The flexible printed wiring board 11 generally has a copper foil pattern 12 formed on a substrate such as a plastic film. Figure 2B is a cross-sectional view taken along the line B-B' of Figure 2, and the solder resist 13 is not shown for the purpose of insulation and to prevent oxidation of the copper foil chisel turn 12, but it is soldered. is formed so as to cover almost the entire area except for the land portion. The structure of the flexible printed wiring board 11 has excellent characteristics that can guarantee a lifespan that can withstand bending tens of thousands to millions of times, but it has the drawback that it cannot be designed to mount heavy components or heat-generating components.

Therefore, in order to solve the drawbacks of the flexible printed wiring board, printed wiring board devices constructed by combining a hard reinforcing plate and a flexible printed wiring board have recently been increasingly used. A conventional example in which the rigid reinforcing plate is composed of a rigid printed wiring board will be described with reference to FIG. The same parts as in FIGS. 1 and 2 are given the same numbers and their explanations will be omitted. Figure 3B is a front view of the state in which adhesive 30 is applied and attached to the substrate side of the rigid printed wiring board 1 in Figure 1 and the flexible printed wiring board 11 in Figure 2, and Figure 3B is the same. Figure 3: Person C-
FIG.

In the rigid printed wiring board removal section 1b, the printed wiring board is made up of only the flexible printed wiring board 11, with an end x1 in contact with the main wiring board Ia& and an end X? in contact with the auxiliary wiring board 1bb. are formed in a straight line. Although not shown, a rigid printed wiring board 1 and a flexible printed wiring board 11
The combined part has the advantage that any parts can be mounted thereon, and the copper foil pattern 12 formed on the 7-lexiple printed wiring board 11 performs electrical connection between the main wiring board 1aa and the auxiliary wiring board 1bb.

However, according to such a connection structure, when the flexible printed wiring board 11 is bent in the direction of the arrow indicated by the solid line B in FIG. Copper foil pattern 12
Small cracks and breaks are likely to occur on the copper foil pattern 12, and the copper foil pattern 12 is particularly vulnerable to bending in the direction of arrow B, and cracks grow after being bent several times, often causing the copper foil pattern 12 to break easily. In this case, it goes without saying that the narrower the copper foil pattern portion is, the more likely it is to break. Said arrow.

Using the B-direction with no bending stress is a design and structure aspect that takes advantage of the advantages of the 7-lexiple printed wiring board.
Furthermore, in the production process, soldering is performed after all mounted components are inserted into the printed wiring board, and then the board is divided and assembled, making it impossible. Moreover, once micro cracks have appeared, there is a risk that defects such as disconnection of the copper foil pattern may occur depending on the subsequent usage conditions.

Therefore, although not shown in the drawings, as a method to solve the above-mentioned drawbacks, the abutting ends of the flexible printed wiring board and the hard reinforcing plate are filled with a reinforcing plate (vinyl tape, etc.) or a viscoelastic material such as silicone rubber. method was being used. 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.

The present invention eliminates the drawbacks of the prior art as described above. The basic technical idea of the present invention is to form a copper foil pattern as wide as possible near the contact end of the flexible printed wiring board and the hard reinforcing plate, where bending stress is concentrated due to bending, and to The center of the hard reinforcing plate is located on the side, and a substantially circular protective film removal part 5o with a convex shape is formed on the copper foil pattern surface on the flexible part 11aa, thereby forming the protective film removal part 60. By attaching solder and relieving the concentration of bending stress on the abutting edge, bending of the flexible printed wiring board near the abutting edge (which can be caused by cracking or failure of the copper foil pattern) can be prevented. This is what I did.

An embodiment of the present invention will be described below with reference to the drawings of FIGS. 4 to 7. FIG. 4 is an enlarged front view of main parts of the conventional example of the present invention shown in FIG. 3. The same parts as those in the conventional example are given the same numbers, so the explanation will be omitted. Contact end of both plates x
1. Although x2 is a straight line and bending stress is concentrated, the copper foil pattern 12 is generally formed with a narrow copper foil pattern, a wide copper foil pattern, and no copper foil pattern.

FIG. 5 is an enlarged front view of main parts of a printed wiring board device showing an embodiment of the present invention, and compared to the conventional example shown in FIG. 4, some of the copper foil patterns 12 are 62
The foil width near the abutting ends X, , X2 of both plates 1, 11 is increased, and a new copper foil pattern 61 is similarly formed, thereby forming the abutting ends X1, . x2 Top Teno copper foil putter: /12
. The difference is that a plurality of new patterns are newly formed on the foil patterns 12, 51 and 52.

FIG. 6 is a sectional view taken along line D-D' in FIG.
, 11 and the copper foil patterns 12, 51, 52 in the vicinity thereof, the protective film (solder resist) 63 on the surface thereof is removed to form many protective film removed parts 60.
Although not shown in the figure, when soldering electronic components, this removed portion 6 is formed during the soldering process.
The approximately hemispherical solder 7o can be attached on the copper foil patterns 12, 51, 52 at the position o.

The state after the soldering process will be explained using the main part sectional view of FIG. 7 showing the completed state of the printed wiring board device. Approximately hemispherical solder T is placed at the abutting ends X, X2 of both plates and in the vicinity thereof.
The mechanical strength is improved by attaching multiple cylinders of o. Therefore, even if the 7-lexiple printed wiring board 11 is bent in the direction indicated by dotted lines M and B in FIG. , it is dispersed and relaxed into a concave and convex curve with a width of about the size that protrudes from the end of the hard reinforcing plate and the flexible part 11aa of 7 degrees of solder. Protective film removal section 60
The shape is not limited to the illustrated example and may be set to any shape as long as the portion protruding into the flexible portion 11aa is approximately circular. The point is, when soldering is completed, use the roughly hemispherical solder T.

If the center of the terminal is located on the hard reinforcing plate side and the soldering is reliable, it is possible to use the same soldering method for electronic component terminals. Furthermore, the thickness of the protective film removed portion 6o can be freely determined depending on the shape of the copper foil pattern. Although not shown in the drawings, adding the removed portion enlarged fins extending radially from the center of the protective film removed portion 60 located on the hard reinforcing plate side produces the effect of preventing the solder 7o and the copper foil pattern from floating. Solder 7 protruding toward the flexible part 11aa side
The dimension 0 is the protective film removal part 5 formed on the copper foil pattern.
It is determined approximately in proportion to the size of o, and it is not necessary to always set it to a constant size. It has been experimentally known that for a substantially circular protective film removal section, setting the diameter to approximately μ is most effective and results in mechanical strength being obtained. The present invention is realized by appropriately setting the number of protective film removal parts 5o in the wide copper foil pattern. With the above-described configuration, even if the flexible portion 11aa is bent and used in general consumer equipment after electronic components (not shown) are attached to the printed wiring board, both printed wiring boards 1. 11
The concentrated bending stress is no longer applied to the abutting ends x, lX2 and is dispersed in the vicinity of the abutting ends. Furthermore, even if the flexible printed wiring board 11 is bent in either direction M or B, the bending stress is applied to the wide area of the copper foil pattern, so there is no risk of cracks or disconnection occurring in the narrow copper foil pattern area. .

In the above embodiments, a rigid printed wiring board is used as the rigid reinforcing plate, but the present invention also includes the case where a rigid insulating substrate is simply used.

As is clear from the above explanation, the printed wiring board device of the present invention is a simple method in which a protective film removal part is formed on the copper foil pattern on the abutting ends of the hard reinforcing plate and the flexible printed wiring board, and solder is applied thereto. With this structure, even if the flexible printed wiring board section is bent, the force acting on the abutting end of the drawing board is not concentrated in a straight line, but is dispersed and alleviated in a concave and convex curve. There is no risk of cracking or breaking the foil pattern.

It also has excellent flexibility, is highly reliable, and has excellent workability and serviceability, making it possible to mass-produce inexpensive printed wiring board devices, and has extremely large practical effects. It is possible to provide.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram when the rigid reinforcing plate according to the present invention is a rigid printed wiring board, where M is a front view, B is a sectional view taken along line A', and Fig. 2 is the configuration of a conventional flexible printed wiring board. In the figure, B is a front view, B is a sectional view taken along the line B-B', FIG. 3 is an enlarged front view of a main part of a part related to the present invention, FIG. 5 is an enlarged front view of a main part of a printed wiring board device according to an embodiment of the present invention, and FIG. 6 is a line nn of FIG. 6. FIG. 7 is a cross-sectional view of essential parts showing a completed printed wiring board device according to an embodiment of the present invention. 1...Hard printed wiring board, 1aa...Main wiring board, 1bb...Auxiliary wiring board, 1cc...
...Holding plate, 12゜51.52...Copper foil pattern, 3,13.63...Solder resist (
Protective film), 11... Flexible printed wiring board, 30... Adhesive, 60... Protective film removed section, X, , X2... Both boards abutting end of 1a
...Slit, 1b...Hard printed wiring board removed section, 1c...Perforation, 1d...
・Dividing recess, 1e...Retaining hole, 11aa・
...Flexible part, 70...Solder. Name of agent: Patent attorney Toshio Nakao and one other person. Figure 2

Claims (1)

[Claims] A hard reinforcing plate is attached to a flexible printed wiring board using plastic, film, etc. as a substrate, and a flexible part consisting only of the flexible printed wiring board part without the hard reinforcing plate is provided on this flexible printed wiring board, and the above-mentioned flexible printed wiring The hard reinforcing plate is attached in a generally circular shape with the center at the center without forming a protective film such as solder resist on the entire surface of the copper foil pattern at the contact end of the flexible part of the board and the hard reinforcing plate and on the copper foil pattern in the vicinity. By forming a curved protruding protective film removed part on the copper foil pattern located on the side and on the flexible part, solder is applied to the protective film removed part in the soldering process and the contact end is A printed wiring board device characterized by relieving concentration of bending stress on the printed wiring board device.