JPH0311796A - Backboard printed board - Google Patents

Abstract

PURPOSE:To improve a printed board of this design in lightning surge resistance and crosstalk resistance by a method wherein a first printed board on which only a pattern mutually connecting the wiring boards is formed, a metal grounding board, and a second printed board on which only an external circuit pattern in printed are stacked up to form the backboard printed board of an electronic device in which many printed wiring boards are housed. CONSTITUTION:A few large externally connecting printed wiring boards 3 are housed as plugged in the side board side of a box-type shelf 1 whose front is open, and many small wiring boards 2 which constitute channel switches are housed as plugged in the central part of the shelf 1. A first printed board 10 on which a pattern mutually connecting the wiring boards 2 is formed, a metal grounding board 15, and a second printed board 20 on which a pattern connecting the printed wiring boards 3 and 2 together is printed are stacked up in this order as a backboard printed board 5, which is mounted on the innermost base of the shelf 1. A circuit lead-in connector A is fixed to the front edge of the wiring board 3, and an external circuit is connected to the wiring board 2 through the intermediary of the wiring board 3 and the printed board 20.

Description

[Detailed Description of the Invention] [Summary] We have developed a backboard printed board that is resistant to lightning surges (and has excellent crosstalk characteristics and is low in cost) for backboard printed circuit boards for electronic devices that accommodate a large number of printed wiring boards in parallel. To provide a backboard printed board for an electronic device in which a large number of printed wiring boards are housed in parallel, a first printed board on which connectors for plugging the printed wiring boards are arranged, and the connectors. The through holes into which the selected connector pins are inserted and connected are constituted by a second printed board arranged as desired, and a metal ground plate interposed between the first printed board and the second printed board.

[Industrial application field]

TECHNICAL FIELD The present invention relates to a backboard print temporary for an electronic device that accommodates a large number of printed wiring boards in parallel.

2. Description of the Related Art Electronic equipment such as electronic exchanges uses electronic devices in which a large number of printed wiring boards are housed on a shelf.

On the other hand, in information systems using electronic exchanges, etc., the exchanges are installed in the main office building, the terminals are installed in remote terminal stations, etc.
The system consists of a terminal, a transmission line, a main distribution board at the main office, a switch, a main distribution board at the main office, a transmission line, and a terminal.

Note that the line cable from the main distribution board is led through the printed wiring board of the electronic equipment of the exchange using a metallic cable.

In this case, lightning strikes on the transmission line wired outdoors cannot be avoided. Therefore, an arrester is installed in the main distribution board where the line is drawn in to absorb the lightning surge voltage and current, but some of this lightning surge voltage and current leaks.
It flows to the electronic equipment that houses the printed wiring boards that make up the electronic exchange.

This leaked lightning surge current is estimated to be (5 (1-100) A), so the pattern width of the printed wiring board directly connected to the line is required to be 0.7M or more, and the pattern spacing is 0.5mm. The above is required.

[Conventional technology]

By the way, if you increase the size of the printed wiring board that makes up the communication path switch and implement multiple lines (8 lines), you will have to replace the large printed wiring board if one line fails due to a lightning surge. , There is a trend to make printed wiring boards smaller and to make printed wiring boards one circuit.

On the other hand, mounting a connector for an external line on each of the printed wiring boards constituting these small communication path switches increases costs.

Therefore, conventionally, an electronic device has a configuration as shown in FIG.

In FIG. 4, l represents several printed wiring boards 3 for external connection.
This is a box-shaped shelf with an open front for an electronic device that accommodates a large number of small printed wiring boards 2 constituting communication path switches and the like in parallel.

On the bottom surface of the shelf 1, there is a connector (not shown) into which the printed wiring board 3 for external connection is plugged, and the printed wiring board 2.
A backboard printed board 30 with a multilayer structure is attached, which is provided with a connector (not shown) for plug-in.

Then, a connector for connecting a line is mounted on the front edge of the printed wiring board 3 for external connection, and the external line is printed via the printed wiring board 3 for external connection - backboard connector backboard printed board 30 - backboard connector. Connected to wiring board 2.

It goes without saying that the printed wiring boards 2 are connected to each other through the patterns of the bank board printed board 30.

[Problems to be Solved by the Invention] By the way, in pattern design, the direction of the running pattern is limited, and cross-pattern running of X/Y is desirable to prevent interlayer crosstalk, and when running patterns in the same direction are adjacent, It is required that this be done through the ground pattern layer.

On the other hand, in the case of backboard printing as described above, the pattern for connecting the printed wiring board 3 for external connection and the printed wiring board 2 is designed so that the pattern width and pattern spacing are set as desired in order to prevent lightning surges, as described above. It needs to be bigger. Furthermore, the traveling direction of these connection patterns and most of the patterns that connect the printed wiring boards 2 to each other is the X direction.

Therefore, the backboard printed board 30 has a multilayer structure consisting of many signal pattern layers and ground pattern layers.
For example, it has a 6.8 layer structure.

Generally, the cost of a printed wiring board is not directly proportional to the number of layers, and as the number of layers increases, the cost increases rapidly.

Therefore, the above-mentioned conventional backboard printed board has a problem of high cost.

The present invention was created in view of these points, and an object of the present invention is to provide a backboard printed board that is resistant to lightning surges, has excellent crosstalk characteristics, and is inexpensive.

[Means to solve the problem]

In order to achieve the above object, the present invention, as illustrated in FIG. A first printed board 1 on which a large number of connectors 2A for plugging in and a connector 3A for plugging in a small number of large external connection mark separate wire boards 3 are mounted in parallel.
0 and connector bin 12- for the external line of connector 2A.
1 is inserted and connected through hole 22, and connector 3A
Through holes 23 into which all connector bins 13 are inserted and connected
A second printed board 20 is provided in which the printed circuit board 20 is arranged in a desired manner.

Then, the first printed board 10 and the second printed board 20
It is configured to be attached to the shelf 1 with a metal ground plate 15 interposed therebetween.

[Function] The backboard printed board 5 configured as described above forms only the external line pattern, that is, the pattern connecting the external connection printed wiring board 3 and the printed wiring board 2, on the second printed board 20, Only patterns connecting printed wiring boards 2 to each other are formed on the first printed board 10.

Therefore, the pattern formed on the second printed board 20 can easily have a desired pattern width and pattern interval, and is resistant to lightning surge current and voltage.

In addition, the second printed board 20 has at most two layers, which is low cost, and the first printed board IO only needs to form patterns that connect the printed wiring boards 2. The number of layers is small and the cost is low.

Further, since the metal ground plate 15 is interposed between the first printed board 10 and the second printed board 20, crosstalk occurs between the first printed board 10 and the second printed board 20. There is no fear.

[Example] The present invention will be specifically described below with reference to the drawings. Note that the same reference numerals indicate the same objects throughout the figures.

Fig. 1 is a diagram of an embodiment of the present invention, (a) is a perspective view shown in separated form, (b) is a side sectional view, Fig. 2 is a wiring diagram of the second printed board, and Fig. 3 is a FIG. 1 is an overall perspective view of an embodiment of the present invention.

In Fig. 3, a box-shaped shelf 1 with an open front has a small number of large printed wiring boards 3 for external connections plugged into the side plate side, and small printed wiring boards 3 constituting communication path switches etc. in the center. A large number of printed wiring boards 2 are plugged in and accommodated.

On the bottom surface of the shelf l, a first printed board IO1 metal ground plate 15 is formed with a pattern connecting the printed wiring boards 2 to each other. A backboard printed board 5 in which a printed wiring board 3 for external connection and a second printed board 20 on which a pattern for connecting the printed wiring board 2 is formed are superimposed in this order.
It is equipped with.

Then, a connector IA for connecting a line is mounted on the front edge of the printed wiring board 3 for external connection, and an external line is connected to the printed wiring board 3 for external connection. It is configured to be connected to each printed wiring board 2 via a second printed wiring board 20, and the connection between each printed wiring board 2 is made using the first printed wiring board 10.
It is configured to do so via .

The first printed board 10 of the backboard printed board 5 is
As shown in detail in FIG. 1, a large number of small connectors 2A into which printed wiring boards 2 are plugged are arranged on the front side, and printed wiring boards 3 for external connection are arranged on both sides of the arranged connectors 2. Relatively large connector 3A to plug in
are installed in parallel.

Connector pins 12-1.12- of these connectors 2A
The connector pins 13 of the connector 2 and the connector 3A are each press-fit pins. That is, in the connectors 2A and 3A, the respective pins are press-fitted into the holes of the connector housing, and the bulges provided at the tips of the connectors come into elastic contact with the through-holes of the first printed board 10, so that the first printed board 10 is connected to the first printed board 10. It is fixedly mounted on the plate 10.

The two connector pins 12-1 for the external line of the connector 2A are long enough to be inserted and soldered into the through holes 22 of the second printed board 20, which will be described later, on the back side of the first printed board 10. It stands out.

Further, all the connector pins 13 at the three corners of the connector protrude long toward the back side of the first printed board 10 so that they can be inserted and soldered into the through holes 22 of the second printed board 20.

Incidentally, on the back surface of the first printed board 10, an elongated earth pattern 11-1 is provided along the upper edge, and an elongated earth pattern 11-2 is provided along the lower edge.

The metal ground plate 15 has the same external shape as the first printed board 10, and is connected to the connector bin 12-1. A slit 17 is provided corresponding to the connector pin 13, and each connector pin 12-1. This is so that the slit 17 passes through it without touching it.

Further, a spacing band 16-1 having a channel shape in side view is provided at the upper edge of the metal ground plate 15, and a spacing band 16-2 having a channel shape in side view is provided at the lower edge. and the front side of the spacing strip 16-2 are brought into contact with the earth pattern 11-1 and the front surface of the spacer band 16-2 is brought into contact with the earth pattern 11-2, respectively.

The second printed board 20 has the same external shape as the first printed board 10, has through holes 22 arranged therein for inserting and soldering connector pins 12-1 for the external line of the connector 2A, and further has through holes 22 arranged therein for insertion and soldering connection. All the connector pins 13 are inserted and soldered through the through holes 23 for connection.

Note that on the front side of the second printed board 20, there is a spacing band 16.
-1.16-2, respectively, are provided with elongated borrowed earth patterns that are in close contact with the rear sides of each of them.

As mentioned above, the first printed board 10, the metal ground plate 1
5. The backboard printed board 5 consisting of the second printed board 20 has screws 25 passed through the screw holes provided at the four corners of each board, and the front side of the first printed board 10 is attached to the shelf l. It is attached to the shelf l by touching it to the frame on the back and tightening the screws.

As illustrated in FIG. 2, the wiring pattern of the second printed circuit board 20 is such that external line patterns are drawn outward from through holes 23 arranged in two rows into which the connector pins 13 of the connector 3A are inserted. By connecting to the through hole 22 into which the connector pin 12-1 of the connector 2A is inserted, the external line pattern width and pattern spacing can be made as thick as desired.

That is, the backboard printed board has an external line pattern that is resistant to lightning surge current and voltage.

Moreover, since it is only necessary to form the first printed circuit board 10 with a pattern that connects the printed wiring boards 2, the number of layers is small, resulting in low cost.

Furthermore, a first printed board 10 and a second printed board 20
Since the metal ground plate 15 is interposed between the first printed board 10 and the second printed board 20, there is no risk of crosstalk occurring between the first printed board 10 and the second printed board 20.

〔Effect of the invention〕

As explained above, the present invention overlaps a first printed board on which only a pattern for connecting printed wiring boards is formed, a metal ground plate, and a second printed board on which only an outgoing line pattern is formed. The present invention is a double backboard printed board constructed of two types of backboards, and has excellent practical effects such as being resistant to lightning surges, having excellent crosstalk characteristics, and being low cost.

[Brief explanation of drawings]

Fig. 1 is a diagram of an embodiment of the present invention, (a) is a perspective view shown in separated form, (b) is a side sectional view, Fig. 2 is a wiring diagram of the second printed board, and Fig. 3 is a FIG. 4 is a perspective view of the entire embodiment of the present invention, and FIG. 4 is a perspective view of a conventional example. In the figure, 1 is a shelf, 2 is a printed wiring board, 3 is a printed wiring board for external connection, 18, 2A, 3A are connectors, 5.30 is a backboard printed board, 10 is a first printed wiring board, 11- 1.11-2 is the ground pattern, 12-1.12
-2.13 is the connector pin, 15 is the metal ground plate, 16-1.16-2 is the spacing band, 17 is the slit, 20 is the second printed board, (CL) Unexploded Hut >f'fix sword? Japanese needle 2 Tomi 3 Ko

Claims (1)

[Claims] In a backboard printed board of an electronic device in which a large number of printed wiring boards are housed in parallel, a connector (2, 3) into which the printed wiring boards (2, 3) are plugged is provided.
2A, 3A) is arranged on a first printed board (10);
Selected connector pin (1) of the connector (2A, 3A)
Through holes (22, 2-1, 13) are inserted and connected
3), a second printed board (20) arranged in a desired manner;
The first printed board (10) and the second printed board (2
1. A backboard printed board comprising: a metal grounding plate (15) interposed between the backboard printed board (15) and a metal grounding plate (15) interposed between the backboard printed board (15)