JPH1073629A - Monitoring apparatus for insulation degradation of printed-circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a monitoring apparatus, for the insulation degradation of a printed-circuit board, by which the progress of the insulation degradation is monitored continuously and by which the state of the insulation degradation can be grasped at an early stage. SOLUTION: In a monitoring apparatus for the insulation degradation of a printed-circuit board, two monitoring electrodes 21a, 21b are formed on a printed-circuit board 11 on which a main circuit is constituted or on another printed-circuit board of the same quality as the printed-circuit board 11, a power supply S and an ampere meter A are connected in series across the monitoring electrodes 21a, 21b, and the insulation degradation of the printed-circuit board is monitored. In the monitoring apparatus, the extension length Lm of the monitoring electrodes 21a, 21b is at the extension length Ls of a pattern whose electric-field strength is maximum in the main circuit, and a voltage is applied across the monitoring electrodes 21a, 21b from the power supply S in such a way that the electric-field strength between them becomes equal to the maximum electric-field strength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulation deterioration monitoring apparatus for monitoring insulation deterioration of a printed circuit board used in an electric or electronic device, particularly, an electric or electronic device used in a bad environment such as outdoors or in a closed space. It relates to a monitoring device.

[0002]

2. Description of the Related Art A printed circuit board is made of a composite material such as a copper cloth or the like having a metal cloth adhered to a plate surface obtained by solidifying a glass cloth with an epoxy resin, or a metal plate of aluminum or the like via an epoxy resin or the like. The metal foil is bonded. The metal foil is patterned as necessary into electrodes and wirings, and leads and stems of electronic and electric components are mounted on each pattern by soldering. In some cases, a through hole for fixing leads and stems is formed in the printed circuit board, and a metal is adhered to the inner surface thereof.

When an electric or electronic device having such a printed circuit board is used in a bad environment such as dust, corrosive gas or humidity, a voltage is applied due to migration or deterioration of an insulating material. It is known that the deterioration of insulation properties between patterns and through holes is accelerated (for example, Technical Report No. 559 of the Institute of Electrical Engineers of Japan, Investigation Committee for Application of Organic Composite Materials to Electro-Electro-photographic Insulation (issued in 1995) )
64-65). Such deterioration of the insulation property progresses most between the patterns in which the electric field strength (voltage between patterns / distance between patterns) between the patterns (hereinafter, the through holes are also represented by the patterns) in the printed circuit board is the largest. Cheap.

FIGS. 6A and 6B schematically show a main part of a printed circuit board used in a conventional electric / electronic device, wherein FIG. 6A is a plan view, and FIG. 6B is a sectional view taken along line XX in FIG. .
A main circuit (not shown) for the operation of the electric / electronic device is formed on the printed circuit board 1, and the pattern pair having the maximum electric field strength is defined as the patterns 2a and 2b. The component 3 is mounted between the patterns 2a and 2b,
The lead 31 of the component 3 is soldered by solder. Other components may be connected to the patterns 2a and 2b.

[0005] The surface of the printed circuit board is often coated with a coating material 4 such as a polyurethane-based resin in order to strengthen the insulating properties and protect the board from contamination entering from the outside. Since electric and electronic devices are aimed at miniaturization, the patterns 2a and 2b are designed with an insulation distance as short as possible. Conventionally, the main circuit is designed so that there is no unnecessary pattern in operation.

[0006]

In an inverter or an uninterruptible power supply using the inverter which requires long-term reliability, it is necessary to inspect a change over time in insulation characteristics (for example, insulation resistance and the like) between patterns. May occur. In such a case, the electrode patterns that can be used for the inspection of the insulation characteristics are the main circuit patterns 2a, 2a,
Only b, the operation of the main circuit must be stopped.

However, it is difficult to stop the operation depending on the operating condition of the apparatus. In practice, the insulation characteristics can be inspected only at the time of periodic inspection. Therefore, prevention of insulation breakdown by early detection of insulation deterioration is a major problem.
In view of the above-mentioned conventional problems, an object of the present invention is to continuously monitor the progress of insulation deterioration, and to monitor the insulation deterioration state at an early stage to prevent the occurrence of an accident due to insulation breakdown by monitoring the insulation deterioration state early. It is to provide a device.

[0008]

In order to achieve the above-mentioned object, two monitors formed on a printed circuit board on which a main circuit is formed or on another printed circuit board of the same quality as the printed circuit board are provided. A power supply and an ammeter are connected in series between an electrode and the monitor electrode, and the insulation deterioration monitoring device for the printed circuit board monitors the insulation deterioration of the printed circuit board based on a current value. A voltage is applied to the monitor electrodes by the power supply so that the electric field strength between the monitor electrodes is equal to or greater than the maximum electric field strength. .

The distance between the monitor electrodes is preferably smaller than the distance between the patterns of the main circuit. The monitor electrodes are preferably comb electrodes that are intricate with each other. It is preferable that an alarm device for issuing an alarm when the monitor current value is equal to or more than a predetermined value is provided.

It is preferable that a control device is provided so that the applied voltage is applied in conjunction with the operation of the main circuit.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. 1 is a schematic configuration diagram of an insulation deterioration monitoring device of an embodiment according to the present invention. Parts corresponding to the conventional printed circuit board (FIG. 4) are denoted by the same reference numerals. In addition to the main circuit patterns 2a and 2b, monitor patterns 21a and 21b dedicated to insulation deterioration monitoring are newly provided on the printed circuit board 11. The monitor patterns include a variable voltage power supply (hereinafter referred to as a power supply) S and an ammeter. A is connected in series. This combination of the power supply S and the ammeter A shows the principle of resistance measurement, and is equivalent to a so-called insulation resistance measuring device. Also, corresponding to the applied voltage of the main circuit,
An AC or pulse power source can be used for the monitor in addition to the DC.

If the pattern of the main circuit is coated, the same coating is applied to the monitor patterns 21a and 21b so that the pattern environment is the same. The distance between the patterns 2a and 2b of the main circuit is Ds, the pattern 2a,
The length at which 2b faces each other at the shortest distance is defined as a track length, this is defined as Ls, and the applied voltage (actual voltage) is defined as Vs.
On the other hand, in the monitor patterns 21a and 21b according to the present invention, similarly, the distance between the patterns is Dm, the length of the facing line is Lm, and the output voltage of the voltage variable power supply E (the monitor voltage applied to the monitor pattern) is Vm. .
When the actual voltage Vs is not so high, the monitor voltage Vm
There is no problem even if the values are the same, but if it is high, there is a problem because the power source E is large and expensive. Therefore, Vm / Dm = Ds / Vs so that the electric field between the patterns becomes equal.
The same characteristic degradation occurs between the monitor patterns as between the patterns of the main circuit.

If Dm between monitor patterns is reduced,
The area required for the monitor pattern is small, and the printed circuit board of the main circuit does not need to be particularly large. Further, the monitor voltage can be reduced, the volume of the power supply S is small, and the cost can be reduced. Further, since Lm ≧ Ls is set for the distance along the track, there are many chances of characteristic degradation occurring between monitor patterns, and the resistance value is small and the current sensitivity during degradation is high. The route does not need to be a straight line, and a double spiral pattern, a comb-shaped combination pattern, and the like have a large (route length / total area of the pattern portion) and a small area load on the printed circuit board.
Also, dispersing the ink at a plurality of locations on the printed circuit board is effective in increasing the chance of contamination.

As described above, since the monitor pattern is not connected to the main circuit, it is possible to always measure the insulation characteristics irrespective of the operation state of the equipment, and it is possible to measure the insulation characteristics without waiting for the periodic inspection as in the prior art. At this point, the insulation deterioration of the printed circuit board can be confirmed. Embodiment 2 FIG. 2 is a schematic configuration diagram of a printed circuit board insulation deterioration monitoring apparatus according to another embodiment of the present invention. In this embodiment, monitor patterns 2a and 2b are formed on a monitor printed circuit board 12 of the same size as the printed circuit board used for the main circuit. This small printed circuit board 12 is installed in the same environment or in the same device as the printed circuit board of the main circuit, and the monitor patterns 2a,
2b is connected in series to the power supply S and the ammeter A.

As in the first embodiment, the deterioration of the insulation of the printed circuit board of the main circuit can be monitored. Further, it is not necessary to newly raise the printed circuit board of the main circuit, and the insulation deterioration monitoring device according to the present invention can be attached to an already-made electric / electronic device later. Embodiment 3 FIG. 3 is a schematic plan view of a monitor pattern of an apparatus for monitoring insulation deterioration of a printed circuit board according to another embodiment of the present invention. Comb-shaped patterns 22a and 22b were combined with the monitor printed board 12 in Example 2. The product of the length lm of the comb blade and its opposing number n (n = 5 in the case of the figure) is the length along the line. (Long line length / total area of pattern portion) is large and current sensitivity is high. Fourth Embodiment FIG. 4 is a schematic configuration diagram of a printed circuit board insulation deterioration monitoring apparatus according to another embodiment of the present invention. The controller for closing the switch SW of the monitor circuit upon detecting the current supply to the pattern 2a or 2b of the main circuit and issuing an alarm by display or sound when the monitor current value exceeds the set value are supplied to the insulation deterioration monitoring device of the first embodiment. An alarm AL is provided.

Even if the main power is turned on, the patterns 2a, 2a
In a device in which the main circuit to which b belongs does not necessarily operate, it is possible to prevent the integration of the voltage application time to the monitor pattern from exceeding the integration of the actual operation time and issuing an alarm earlier than necessary. In addition, monitoring is facilitated by the generation of an alarm. Fifth Embodiment When the pattern to be monitored in the main circuit is small and simple, the following may be performed.

FIG. 5 is a schematic structural view of a printed circuit board insulation deterioration monitoring apparatus according to another embodiment of the present invention. The monitor circuit of this embodiment includes the electrodes 2a and 2b, the electronic component 3
And the post 31 and the coating material 4 were all the same as the main circuit to be monitored. The same voltage was applied. Accordingly, the same deterioration can be expected to occur, and the ammeter can detect deterioration that is less severe than the deterioration state that leads to an actual accident.

[0018]

According to the present invention, between two monitor electrodes formed on a printed circuit board on which a main circuit is formed or on another printed circuit board of the same quality as the printed circuit board, between the monitor electrodes A power supply and an ammeter are connected in series, the insulation deterioration monitoring device of the printed circuit board for monitoring the insulation deterioration of the printed circuit board by the current value, the length along the monitor electrode is the maximum electric field strength in the main circuit. It is longer than the length along a certain pattern, and a voltage is applied by the power supply to the monitor electrodes so that the electric field strength between them becomes equal to the maximum electric field strength. It is possible to always measure the insulation characteristics, and it is possible to check the insulation deterioration of the printed circuit board at any time without waiting for the periodic inspection as in the past, Accidents caused by lint insulating substrate degradation can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an apparatus for monitoring insulation deterioration of a printed circuit board according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an apparatus for monitoring insulation deterioration of a printed circuit board according to another embodiment of the present invention.

FIG. 3 is a schematic plan view of a monitor pattern of an apparatus for monitoring insulation deterioration of a printed circuit board according to another embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a printed circuit board insulation deterioration monitoring apparatus according to another embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a printed circuit board insulation deterioration monitoring apparatus according to another embodiment of the present invention.

6A and 6B show a main part of a printed circuit board used in a conventional electric / electronic device, wherein FIG. 6A is a plan view and FIG.
XX sectional view in FIG.

[Explanation of symbols]

 Reference Signs List 1 printed circuit board 11 printed circuit board 12 small printed circuit board 2a electrode 2b electrode 21a electrode 21b electrode 22a electrode 22b electrode 3 electric component 4 coating material S power supply A ammeter Ds distance between patterns Ls length along line Dm distance between monitor patterns Lm monitor pattern Line length C Controller SW Switch AL Alarm

Claims (5)

[Claims] A power supply and an ammeter are provided between two monitor electrodes formed on a printed circuit board on which a main circuit is formed or on another printed circuit board of the same type as the printed circuit board. A printed circuit board insulation deterioration monitoring device which is connected in series and monitors insulation deterioration of the printed circuit board based on a current value, wherein a length along a line of the monitor electrode is a length along a pattern which is a maximum electric field strength in a main circuit. As described above, a voltage is applied to the monitor electrode by the power supply so that an electric field intensity between the monitor electrodes becomes equal to the maximum electric field intensity. 2. The apparatus according to claim 1, wherein a distance between said monitor electrodes is smaller than a distance between said patterns of a main circuit.
2. A device for monitoring insulation deterioration of a printed circuit board according to claim 1. 3. An apparatus according to claim 1, wherein said monitor electrodes are comb-shaped electrodes intertwined with each other. 4. An apparatus according to claim 1, further comprising an alarm device for issuing an alarm when said monitor current value is equal to or greater than a predetermined value. 5. The printed circuit board insulation deterioration monitoring device according to claim 1, wherein a control device is provided so that the applied voltage is applied in conjunction with the operation of the main circuit.