JPH05149990A - Printed wiring board - Google Patents

Abstract

PURPOSE:To accurately and reliably inspect in a short time by cutting a part of a loop circuit of a circuit pattern in a manner to be easily connected. CONSTITUTION:A pattern 8 is provided to suppress influences of the signal delay at the farthest land 4 among lands 2, 3, 4 for input pins of signals sequentially connected by a land 1 at an output pin of signals and a pattern 7. The pattern is cut at an optional point of the pattern 8, and lands 5, 6 for through holes are provided at the confronting end points of the cut pattern. In the case, for example, where the pin is brought in touch with the lands 1 and 4 to conduct checking, it is possible to check even if either of the patterns 7 and 8 is opened. In other words, it is possible to detect an opening if the route of lands 5-1-2-3-4-6 is opened somewhere by bringing the pin in touch with the lands 5 and 6. After the inspection, the lands 5 and 6 are connected through a jumper wire.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board used for electronic equipment and the like.

[0002]

2. Description of the Related Art With the development of electronic technology, the operating frequency of an electric circuit mounted on a printed wiring board becomes higher, and problems such as delay of signal transmission time, occurrence of crosstalk, and generated noise become apparent. In order to solve these problems, a method of forming a wiring pattern in a loop has been devised.

FIG. 4 is a diagram showing a conventional example of a loop circuit for preventing signal delay, and FIG. 5 is a diagram showing a conventional example of a loop circuit for preventing crosstalk noise.

In FIG. 4, four lands 11, 1 are provided.
2, 13, 14 are sequentially connected by the pattern 17,
Further, only the lands 11 and 14 at both ends are connected by another pattern 18, and the patterns 17 and 18 form a loop circuit. This prevents a signal delay between the lands 11 and 14.

In FIG. 5, a ground pattern 21 is formed as a loop circuit around the signal pattern 20. This prevents crosstalk noise to and from the signal pattern 20.

[0006]

Conventionally, a bare board checker for electrically conducting a continuity check and a visual inspection by a human are known as an inspection method in a manufacturing process of a printed wiring board. In the loop circuit section, if there is an open (cut) point 19 in the loop section, the bare board checker cannot detect it. In general, the operation of the bare board checker is conducted by contacting the tip end of the pattern to be inspected, that is, both ends in the case of a single line, and the tip ends of three points in the case of T-branch with a pin or a conductive rubber to conduct the pattern. Detects its own open and short circuit with other patterns. In the case of the circuit as shown in FIG. 4, the pins are brought into contact with the land 11 and the land 14, but even if the open portion 19 exists, the land 1
Opening cannot be detected because current flows in the path of 1-pattern 18-land 14. Therefore, in such a case, there is no method other than relying on a human visual inspection, and it is difficult to perform an accurate and reliable inspection in a short time.

It is an object of the present invention to provide a printed wiring board which can accurately and reliably inspect open (cut) in a short time even if there is a loop circuit.

[0008]

A printed wiring board according to the present invention is a printed wiring board in which a part of a circuit pattern arbitrarily formed on an insulating substrate electrically forms a loop circuit. It is characterized in that a part of the circuit is cut so that it can be easily connected.

[0009]

According to the present invention, a printed wiring board is manufactured in a state where any portion in the loop is cut in advance, and the printed wiring board is a non-defective product by a bare board checker or the like using two cut points facing each other. It is possible to manufacture an electrically excellent printed wiring board as originally designed, by confirming that, and then connecting and using the two points.

[0010]

FIG. 1 is a diagram showing an embodiment of the present invention.

Of the lands 2, 3 and 4 provided for the signal input pins which are sequentially connected by the pattern 1 and the land 1 provided to the signal output pin, the influence of the signal delay on the land 4 at the farthest point is considered. Pattern 8 provided to suppress
The pattern is cut at an arbitrary point, and through-hole lands 5 and 6 are provided at the opposing end points.

FIG. 2 is a wiring diagram of the logic circuit which is the basis of this embodiment.

According to the present embodiment, for example, when the pins are brought into contact with the lands 1 and 4 for checking, patterns 7 or 8
Can be detected even if either one of them is open. That is, by contacting the pins with the lands 5 and 6 and checking them, it is possible to detect if there is an open portion somewhere in the route of the land 5-1-2-3-4-6.
After the inspection is completed, connect lands 5 and 6 with jumper wires.

In the above-described embodiment, the cutting points made in advance are connected by jumper wires, but any connection can be made as long as reliable and inexpensive connection can be made at the time of mounting the parts. For example, as shown in FIG. As shown, the end points of the cut pattern and the wide portions 5a and 6a are opposed to each other, or, as shown in FIG. 3B, the wide portion 5b having the concave portion and the wide portion 6b having the convex portion are opposed to each other. You can Alternatively, a method of mounting a lead component or a chip component having almost zero resistance, an IC having a short circuit incorporated therein, a method of connecting by soldering, or the like can be considered.

In addition, even if the wiring pattern is not in a loop shape, the route may be long or may be close to an adjacent pattern, and it may be better to cut the pattern and check it. , This technology can be applied.

[0016]

As described above, according to the present invention, the cut inspection of the loop circuit can be performed accurately and surely in a short time by keeping a part of the loop circuit cut. Can be manufactured.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a wiring diagram of a logic circuit on which the embodiment of FIG. 1 is based.

3A and 3B are diagrams showing examples of the pattern shape of a cut portion.

FIG. 4 is a diagram showing a conventional example.

FIG. 5 is a diagram showing a conventional example.

[Explanation of symbols]

 1 Land for signal output 2, 3, 4 Land for input signal 5, 6 Land for cutting point 5a, 5b, 6a, 6b Wide part 7, 8 patterns

Claims (1)

[Claims] 1. In a printed wiring board in which a part of a circuit pattern arbitrarily formed on an insulating substrate electrically forms a loop circuit, the part of the loop circuit is cut so that it can be easily connected. A printed wiring board, which has a formed shape.