JPH04178571A - Inspecting method for printed board - Google Patents

Abstract

PURPOSE:To search a short-circuited position while holding the state of the short-circuited position by obtaining the potential distribution of the first and second printed boards, and detecting the positions of both boards having the same potential without exciting the short-circuited position between the printed boards. CONSTITUTION:A current 16 is fed to a printed board 12, and the potential of a printed board 11 is measured with a probe 17 and a voltmeter 18. The probe 17 is moved to measure the potential at multiple points in the X-direction from the current source side 191 to the current sink side 192 on the board 12. The position in the X-direction where the potential of the board 11 and the potential of the board 12 become the same potential is obtained. The current source and current sink on the board 12 are connected in the Y-direction, and the position in the Y-direction where the potential of the board 11 and the potential of the board 12 become the same potential is obtained likewise. The portion where the position in the X-direction and the position in the Y-direction obtained in the above processing intersect is detected as the short-circuited position.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inspection method for searching for short-circuits occurring between conductor patterns on a printed circuit board.

[Prior art] Printed circuit boards are becoming more dense as electronic devices become smaller and more dense.
This is achieved by narrowing the pattern width and pattern spacing.

For this reason, there is a tendency for short-circuit defects to increase in printed circuit boards with higher density and finer features, and various inspection methods and inspection apparatuses have been developed and put into practical use.

FIG. 2 is a diagram showing an example of a conventional printed circuit board inspection apparatus (Japanese Unexamined Patent Publication No. 2-62975).

In FIG. 2, 21 and 22 are first and second printed circuit boards on which circuit patterns are formed, respectively, and 23 is
This is a defective point where there is a short circuit between circuit patterns. In order to detect this defective location, an AC signal 25 of a predetermined frequency is supplied from an AC power supply 24 between the first and second printed circuit boards 21 and 22. Then, the magnetic field detection sensor 26 tracks whether there is a short circuit.

In other words, if there is no short circuit, the alternating current signal 25 will not flow and the magnetic field detection sensor 26 will not detect a change in the magnetic field. However, if there is a short circuit, a magnetic field will be generated along the short circuit current, so this magnetic field is Detected by the ratio sensor 26,
By observing the strength of the magnetic field with an oscilloscope 27, the location of the short circuit can be found.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional detection device, since current flows through the short-circuited portion, the portion changes to a carbonized state, making it impossible to maintain the short-circuited state, resulting in a short-circuit failure. This has the drawback of making it difficult to investigate the cause of the problem, and also partially damaging the printed circuit board.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for inspecting a printed circuit board that can easily and reliably search for a short circuit while maintaining the state of the short circuit.

Means for Solving Problem C] In order to achieve the above object, in the inspection method of the present invention, in the method of inspecting short-circuit points between a plurality of printed circuit boards, without energizing the short-circuit points between the printed circuit boards, The present invention is characterized in that the potential distributions of the first and second printed circuit boards are determined, and a position of the same potential on the first and second printed circuit boards is detected as a short-circuit location.

[Function 1] According to the above-mentioned means, since the short-circuit defective location between the printed circuit boards is searched for without passing current through the short-circuit defective location, the short-circuit defective state is maintained.
Moreover, it does not damage the printed circuit board.

[Example] Hereinafter, an example of the present invention will be specifically described using the drawings.

FIG. 1 is a diagram showing the configuration of an inspection device according to an embodiment of the present invention. In the figure, 11 and I2 are printed circuit boards (for example, power supply layer) each having a circuit pattern formed thereon, and a short-circuit defect point 1 to be detected between these boards.
There are 3. In this embodiment, in order to detect short-circuit defects, the DC power supply 14 is connected to only one printed circuit board 12.
It is configured to supply 15 is the protective resistance, 1
6 is a current flowing through the printed circuit board 12. Then, the short-circuit defective location is detected by the probe J7 and the voltmeter 18.

That is, with the current 16 flowing through the printed circuit board 12, the potential Va of the printed circuit board 11 is first measured using the probe 17 and the voltmeter 18. Next, printed circuit board J2
The potential vb at a plurality of points in the X direction from the current source side 191 to the current sink side 192 above is measured by moving the probe 17.

Through this processing, the position in the X direction where the potential Va of the printed circuit board 11 and the potential Vb of the printed circuit board 12 are the same potential is determined.

Then, the current source and current sink on the printed circuit board 12 are changed in the Y direction, and the potential Va of the printed circuit board 11 and the potential v of the printed circuit board 12 are changed in the same manner as described above.
Find the position in the Y direction where b has the same potential.

The portion where the X-direction position and the Y-direction position obtained through the above processing intersect is detected as a short-circuit location.

As described above, in the present invention, since no current is passed through the defective short-circuit portion during inspection, the defective short-circuit portion does not become carbonized and maintains its state, so there is no hindrance in investigating the cause of the defective short-circuit portion. This will not cause any damage to the printed circuit board.

In addition, although the above-mentioned example was shown about a two-layer printed circuit board, it goes without saying that it is not limited to this and can also be applied to a multi-layer printed circuit board.

[Advantageous Effects of the Invention 1] As explained above, according to the present invention, the short-circuit defective location between printed circuit boards is searched for without passing current through the short-circuit defective location, so that the short-circuit defective state is maintained. , and does not cause any damage to the printed circuit board. Furthermore, the configuration is simplified compared to conventional detection devices.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing the configuration of an inspection device according to an embodiment of the present invention, and FIG. 2 is a diagram showing an example of a conventional printed circuit board inspection device. 11.12... Printed circuit board, 13... Short circuit defective location, 14... DC power supply,
17. Probe, 18. Voltmeter.

Claims (1)

[Claims] (1) In a method of inspecting short-circuit points between a plurality of printed circuit boards, the potential distribution of the first and second printed circuit boards is determined without applying current to the short-circuit points between the printed circuit boards, and the potential distribution of the first and second printed circuit boards is determined. A printed circuit board inspection method characterized by detecting positions of the same potential on the printed circuit board as short-circuit points.