JPH0141270B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a printed wiring board (so-called printed circuit board, hereinafter referred to as a PC board), and particularly to a printed circuit board on which a required wiring pattern is formed and electronic components are mounted. The present invention relates to a printed wiring board in which a sub printed wiring board is attached to a printed wiring board.

[Technical background of the invention and its problems]

The wiring pattern of a PC board is designed and manufactured according to the function and purpose of the PC board, but there may be cases where it becomes necessary to change the function of the PC board, or it becomes necessary to modify it due to a design error. Jumper wiring is used as a countermeasure for such cases. However, conventional jumper wiring is done manually for each PC board, and jumper wiring requires preliminary processing such as cutting the wires by length and stripping the insulation coating. Therefore, wiring work is time-consuming and wiring leakage may occur. Furthermore, the jumper wiring work requires skill, which reduces productivity.

Therefore, in order to streamline the wiring work associated with jumper wiring and to prevent wiring leakage, the inventor first formed a wiring pattern for jumper wiring on a sub-PC board, and The main PC
We proposed a PC board that could be attached to the part of the board where the jumper wiring was to be made and electrical connections could be made (Japanese Patent Application No. 160121/1982).

3 and 4 show an example of the PC board 1 according to the above proposal. As shown in the figure, there are required wiring patterns 5 and lands 6 on the back side of the main PC board 7.
are formed, and leads 3' of various components 3 are inserted through the holes of each land 6 and soldered to the wiring pattern 5 and the land 6 with solder 4. And the Lord
In the part of the PC board 7 where jumper wiring is to be done, there is a
A PC board 8 is attached by adhesive or adhesive tape. Also, for example, a pattern is formed such that the position of the land 10 of the sub-PC board 8 is aligned with the position of the land 6 of the jumper wiring portion of the main PC board 7, and the lead 3' of each component 3 is
The secondary PC board and the main PC board are electrically connected by soldering so that the through hole 11 of the corresponding land 10 of the PC board 8 is also inserted.

However, in the PC board formed in this way, the wiring pattern 5 wired on the main PC board and the cut points 5' for modification thereof are hidden in the sub PC board 8, and the cut points 5' etc. of the wiring pattern are hidden in the sub PC board 8. The disadvantage was that it was not possible to confirm the Furthermore, if you forget to cut the pattern 5' or if you need to make a new cut to the pattern, you will need to perform processes such as peeling off the sub-PC board that has already been mounted, which requires a lot of time and materials for modification work. I had to.

[Purpose of the invention]

An object of the present invention is to facilitate confirmation of whether or not the wiring pattern on the main PC board located below the mounted sub-PC board has been cut.

[Summary of the invention]

In the PC board of the present invention, after the secondary PC board is mounted, the required portions of the wiring pattern of the main PC board are
It is characterized in that the sub-PC board is configured so that it is visible through the PC board.

[Embodiments of the invention]

1 and 2 show an embodiment of the present invention. As shown in the figure, the required wiring patterns 5 and lands 6 are formed on the back surface of the main PC board 7, and the leads 3' of various parts 3 are inserted into the holes of each land 6.
is inserted, and solder 4 is applied to wiring pattern 5 and land 6.
It is soldered by. Then, a sub PC board 8 is attached to a portion of the main PC board 7 where jumper wiring is to be performed. This installation can be done, for example, on a secondary PC.
This may be done by using an adhesive tape provided on the side of the board 8 facing the main PC board 7, or by using an adhesive such as a thermosetting resin between the sub PC board 8 and the main PC board 7. This may also be done by interposing and applying heat press from the side of the sub PC board 8.

Also, for example, a pattern is formed such that the position of the land 10 of the sub PC board 8 is aligned with the position of the land 6 of the jumper wiring portion of the main PC board 7, and the leads 3' of each component 3 are aligned with the position of the land 6 of the jumper wiring part of the main PC board 7. By inserting the through hole 11 of the corresponding land 10 and soldering, the sub PC board and the main PC board are connected.
Make electrical connection with the board. At this time, the secondary PC
The through hole 11 of the substrate is formed slightly larger, and the sub-hole 11 is made slightly larger.
Lay the PC board 8 on the main PC board 7 and land 10
By performing soldering from the side, molten solder flows from the land 10 side to the land 6 side through the through hole 11. Or, first
Solder land 6 of the PC board and lead 3', then overlap the sub PC board 8 and connect lead 3' to land 1.
0 and solder. In this case as well,
The through hole 11 of the PC board connects the main PC board 6 and the lead 3'.
It is best to make it slightly larger to avoid solder fillets (protrusions) when soldering with.

The above points are substantially the same as the PC board shown in FIGS. 3 and 4, but the PC board according to the present invention differs in that through holes 12 are provided at various locations on the sub PC board 8.
This through hole 12 is provided in the wiring pattern 7 at a position corresponding to a cutting location and a location where cutting may be necessary due to a future design change or the like.

In this way, in the PC board of the above embodiment, the secondary PC
A through hole is provided in the board, and the main PC is inserted through this hole.
Since the presence or absence of a cut in the wiring pattern on the board can be visually confirmed, inspection can be carried out easily and in a short time. In addition, located under the sub-PC board,
Even when it becomes necessary to cut a new wiring pattern on the main PC board, the cutter can be inserted through the through hole and the wiring pattern can be cut, eliminating the need to peel off the sub PC board for cutting.

In the above embodiment, the wiring pattern on the main PC board can be seen by providing a through hole in the sub PC board, but instead, the sub PC board may be formed of a transparent or semi-transparent plate. You can also use it as In this case, by forming the sub-PC board from a material that is easy to cut, the wiring pattern 5 can be cut and removed together with the sub-PC board. Therefore,
There is no need to peel off the sub-PC board in order to cut the wiring pattern 5.

If a pattern or a land that does not need to be connected to the main PC board 7 is formed on the side of the sub PC board 8 facing the main PC board 8, an insulation treatment such as providing an insulating layer covering the pattern or land is performed. By rubbing, contact with the pattern on the main PC board 7 side can be prevented.

When the sub PC board 8 is formed of a thin flexible PC board, workability is improved, such as being able to easily attach it to the main PC board 7. Moreover,
The difference in unevenness between the back side of the PC board 1 where the sub PC board 8 is provided and the part where the sub PC board 8 is not provided, in other words, the difference (projection length) from the back surface of the main PC board 7 to the back surface of the sub PC board 8. ) becomes smaller, making it easier and more reliable to conduct soldering work and circuit tests by bringing the contactor into contact with the land. Furthermore, cutting of the wiring pattern 5 becomes easier.

〔Effect of the invention〕

As described above, according to the present invention, it is possible not only to improve the efficiency of wiring work and prevent wiring leakage, but also to easily and reliably check whether the wiring pattern on the main PC board has been cut.

Note that the pattern formed on the sub-printed board is not limited to the jumper wiring pattern. In other words, if the desired electrical circuit can be formed by locally increasing the number of wiring layers without having to increase the number of wiring layers over the entire surface of the main printed wiring board, the sub printed wiring board may be mounted on the main printed wiring board. This goal can thus be achieved. The cost of increasing the number of wiring layers on the main printed wiring board is equivalent to the cost of one single layer board per layer, but this cost can be reduced by installing a sub printed wiring board instead. .

[Brief explanation of drawings]

Fig. 1 is a diagram showing a PC board according to an embodiment of the present invention, Fig. 2 is a sectional view taken along the line - - in Fig. 1, Fig. 3 is a diagram showing a PC board previously proposed by the present inventor, and Fig. 4 is the third
FIG. 3...Parts, 3'...Lead, 4...Solder, 5
...Wiring pattern, 6...Land, 7...Main PC
Board, 8...Sub-PC board, 9...Wiring pattern,
10...Land, 11...Through hole, 12...Through hole.

Claims (1)

[Scope of Claims] 1. A sub-printed wiring board on which a wiring pattern is formed separately from the wiring pattern on the main printed wiring board is attached to a corresponding location on the main printed wiring board to make the required electrical connection. In the printed wiring board, the sub printed wiring board is configured such that a required portion of the wiring pattern of the main printed wiring board is visible through the sub printed wiring board after the sub printed wiring board is mounted. A printed wiring board characterized by: 2. The printed wiring board according to claim 1, wherein the sub printed wiring board is provided with a through hole at a position corresponding to the required portion of the wiring pattern. 3. A jumper wiring pattern for changing or adding to the wiring pattern of the main printed wiring board is formed on the sub printed wiring board. Printed wiring board described in .