JPH09113565A - Liquid leakage detecting method for electrical parts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the breaking of wiring pattern, fuming and firing by detecting liquid leakage in the service state of a printed circuit board mounted with electrical parts such as an aluminum electrolytic capacitor containing conductive liquid internally. SOLUTION: A liquid leakage detecting pattern 2 and a detecting circuit 8 for applying specified voltage to the detecting pattern 2 to monitor are provided directly below the mounted position of an electrical part with the possibility of liquid leakage on a printed circuit board 5. In the case of conductive liquid leaking, the voltage change of the detecting pattern 2 caused by the short circuit between the detecting pattern 2 and a terminal of the electrical part is detected to detect the liquid leakage of the electrical part. Accordingly, when a fault is developed to a device using an aluminum electrolytic capacitor or a battery having conductive liquid internally, an accident such as the breaking of wiring pattern, fuming and firing can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting leakage of an electric component containing an electrically conductive liquid, and particularly to a conductive liquid (electrolyte) such as an aluminum electrolytic capacitor or a battery. The present invention relates to a leak detection method for an electric component, which is capable of detecting a leak on a printed circuit board from an electric component having a built-in circuit.

[0002]

2. Description of the Related Art Generally, electric parts such as batteries and aluminum electrolytic capacitors mounted on a printed circuit board are used by encapsulating a conductive electrolytic solution inside and connecting the terminals to the wiring pattern of the printed circuit board. ing.

Electric components such as batteries / aluminum electrolytic capacitors sealed with such a conductive solution are less likely to leak out of the sealed conductive electrolytic solution under normal use conditions, but are defective during manufacturing. Due to poor airtightness / application of overvoltage or reverse voltage / application of excessive ripple or AC voltage, there is a possibility that the internal heat will be generated and the internal pressure will rise, causing the conductive liquid (electrolytic solution) to leak to the outside. Further, these electrical parts are not limited to the above-mentioned electrical stress, and for example, when mechanical stress is erroneously applied during the assembly process or maintenance work of the printed circuit board, the electrolytic solution may leak to the outside. It was If this electrolytic solution leaks from the electric parts, the conductive electrolytic solution may short-circuit between the wiring patterns on the printed circuit board, and in the worst case, the wiring pattern may be broken due to the migration action, or smoke and ignition may occur. There was a problem called.

It should be noted that the possibility that the electric parts such as the aluminum electrolytic capacitor may leak may be explained by, for example, TEC issued by Hitachi Capacitor Co., Ltd. on August 21, 1987.
HNICAL REPORT, NO. AC-966 "Aluminum Electrolytic Capacitor".

[0005]

In order to prevent the above-mentioned danger, in the printed circuit board according to the prior art, as a countermeasure against the leakage of the conductive liquid, a wiring pattern or a wiring pattern is provided directly below the electric parts mounted on the printed circuit board. It has been attempted to prevent short circuits between patterns due to a conductive liquid by not providing a hole or the like and designing a printed circuit board with a certain distance between the wiring patterns. However, it is extremely difficult to completely prevent liquid leakage from electric parts such as aluminum electrolytic capacitors, and the conductive liquid such as electrolytic solution leaking from the electric parts easily spreads on the printed circuit board. Since the preventive measures by the conventional technology are not sufficient,
There was a problem that the risk of wiring pattern breakage, smoke emission and ignition could not be prevented.

An object of the present invention is to eliminate the above-mentioned problems caused by the prior art, and to prevent leakage of liquid during use when an electric component containing a conductive liquid such as an aluminum electrolytic capacitor or a battery is mounted on a printed circuit board. It is an object of the present invention to provide a liquid leakage detection method for an electric component, which is capable of detecting and preventing disconnection of a wiring pattern, smoke and ignition.

[0007]

In order to achieve the above object, the present invention provides a method for detecting leakage of an electric component, which detects a leak from an electric component containing a conductive liquid mounted on a printed circuit board. The terminal of the electric component is connected to the conductive wiring pattern of the printed circuit board, and the leak detection pattern whose potential changes when the conductive liquid leaked from the electric component comes into contact with the vicinity of the wiring pattern is wired. When the conductive liquid leaked from the electric component short-circuits the leak detection pattern and the electric component terminal, the first feature is to detect a failure by changing the potential of the conductor.

Further, the method for detecting liquid leakage according to the present invention comprises the first
In addition to the above feature, a second feature is that the detection conductive pattern is arranged in a shape that covers the periphery of the terminal of the electric component in a position directly below the electric component in a non-contact manner, and further, the leak detection conductive pattern and the electrical component. The third feature is that the interval between the terminal and the terminal is narrowed to increase the leak detection level, or the interval is increased to decrease the leak detection level.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a method for detecting leakage of an electric component according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram for explaining a printed circuit board to which a liquid leakage detection method for detecting electrolyte leakage of an aluminum electrolytic capacitor according to the present embodiment is applied, and FIG. 2 is an aluminum electrolytic capacitor on a printed circuit board and a liquid leakage detection method. FIG. 3 is a diagram for explaining an example of the detection pattern, and FIG. 3 is a diagram for explaining the dimensional relationship between the electrodes of the aluminum electrolytic capacitor and the detection pattern.

As shown in FIG. 1, a printed circuit board 5 to which the liquid leakage detection method according to the present embodiment is applied is provided between a plurality of aluminum electrolytic capacitors 1 arranged at predetermined positions and a terminal 20 directly below the aluminum electrolytic capacitors 1. A pattern 2 for detecting a liquid leakage that passes through, a detection circuit 8 connected to an end of the detection pattern 2 for detecting a voltage fluctuation of the pattern 2, and a detection result from the detection circuit 8 A power supply microcomputer 10 that controls the power supply accordingly, and a power supply 9 that supplies power to the power supply microcomputer 10 and other parts.

The detection circuit 8 comprises a plurality of resistors R1 to R5 for voltage fixing, a window comparator 6 for voltage comparison, and a logic IC 7. The resistors R1 and R2 are
The detection pattern by dividing the voltage supplied from the power supply Vcc.
Determine the voltage on pin 2. If the resistance values of the resistors R1 and R2 are as small as several Ω, the voltage fluctuation becomes small when a conductive liquid such as an electrolytic solution is short-circuited between the detection pattern 2 and the electrodes of the aluminum electrolytic capacitor 1. This is unsuitable because the voltage comparator 6 for voltage comparison does not operate. On the contrary, if the resistance value of the resistors R1 and R2 is too large, such as several MΩ, it is unsuitable because the voltage is apt to change due to the influence of noise. Therefore, the resistance values of the resistors R1 and R2 are preferably several kΩ to several tens kΩ. The comparison voltage input to the voltage comparator window comparators 6A and 6B is determined by the resistance values of the resistors R3, R4 and R5. The voltage of the detection pattern 2 is 1/2 Vcc because the resistors R1 and R2 have the same resistance value. Further, the comparison voltage of the window comparator 6B becomes 2/5 Vcc because the resistors R3 to R5 have the same resistance value, and the comparison voltage of the window comparator 6A becomes 3/5 Vcc.

Further, the detection pattern 2 immediately below each aluminum electrolytic capacitor 1 has a terminal 2 of the capacitor 1 as shown in FIG.
0 is arranged on the printed circuit board 5 so as to project so as to have a semi-arcuate concave space that surrounds the positive electrode side pattern 3 and the negative electrode side pattern 4 electrically connected to 0. This terminal 20
The dimension between them is usually about 5 mm, and the dimension of the narrow linear portion of the detection pattern 2 is preferably about 1 to 2 mm.

In the detection pattern 2 thus constructed, the detection area of the conductive liquid is widened so as to have a semi-circular space, so that the probability of contact with the detection pattern is increased and liquid leakage occurs. It is possible to change the level of liquid leakage detection by facilitating the detection of the liquid leakage or by increasing the distance between the detection pattern 2 and the aluminum electrolytic capacitor electrode. The power supply microcomputer 10 and / or the power supply 9 may be mounted on a printed circuit board or may be separately provided.

In the printed circuit board 5 thus constructed, the voltage of the detection pattern 2 of the detection circuit 8 under normal conditions is 1 / 2V.
cc, the wind comparators 6A and 6B do not operate, and the output of the logic IC 7 (OR circuit) maintains the L level. However, if the electrolytic solution leaks from the aluminum electrolytic capacitor 1 due to some cause and short-circuits between the cathode side pattern 4 of the aluminum electrolytic capacitor 1 and the detection pattern 2, the voltage is fixed at 1/2 Vcc. The potential of the detection pattern 2 gradually decreases to 2/5 Vcc or less, and the window comparator 6B operates. By this operation, the output of the comparator 6B becomes H level, the output of the lodge IC 7 (OR circuit) also changes to H level,
It operates so as to interrupt the power supply control microcomputer 10 connected ahead of the logic IC 7 and stop the power supply from the power supply 9 to the printed circuit board. When the leaked electrolytic solution is short-circuited between the anode side pattern 3 of the aluminum electrolytic capacitor 1 and the detection pattern 2, the potential of the detection pattern 2 gradually rises to 3/5 Vcc. As a result, the window comparator 6A operates and the output becomes H level,
Subsequent circuits operate to interrupt the power supply control microcomputer 10 and stop the power supply from the power supply 9 to the printed circuit board, as in the case where the circuit is short-circuited with the cathode side pattern 4 described above.

As described above, in the printed circuit board to which the liquid leakage detection method according to the present embodiment is applied, if the liquid leaks from an electric component containing an electrically conductive liquid inside an aluminum electrolytic capacitor or the like, the printed circuit board is arranged immediately below the electric component. By monitoring the potential at which the conductive liquid contacts the detection pattern and changes, it is possible to detect the liquid leakage from the electric component. This allows
It is possible to prevent damage due to liquid leakage, such as smoke and ignition.

In the above embodiment, the operation after the liquid leakage is detected is to stop the power supply to the printed circuit board. However, the operation is not limited to this, and the power supply to the entire apparatus mounting the printed circuit board is performed. May be stopped and / or a warning sound to the administrator may be sounded or a warning may be displayed simultaneously with the power supply.

Further, the detection pattern applied to the liquid leakage detection method according to the present invention is not limited to that of the above-mentioned embodiment, and for example, as shown in FIG. 3, between the terminals 20 immediately below the electric parts such as the aluminum electrolytic capacitor 1 and the like. It may be a shape that linearly passes through. As for the dimensional relationship between the detection pattern 2 and the terminal 20, the dimension L1 between the positive electrode side pattern 3 and the negative electrode side pattern 4 covering the terminal 20 is about 3 mm, and the width L1 of the linear detection pattern 2 is as shown in FIG. Is about 1 mm,
It is preferable that the respective dimensions L3 and L4 between both ends of the detection pattern 2 and between the positive electrode side pattern 3 and the negative electrode side pattern 4 are about 1 mm.

As for these dimensional relationships, the dimension L3 and L4 between the terminal and the electrode are narrowed when the leak detection sensitivity is increased, and the leak detection sensitivity is lowered, for example, in the detection pattern as in the embodiment of FIG. It is conceivable to make it larger by reducing the width. In order to further increase the detection sensitivity, it is conceivable to widen in the concave shape having a large contact area or the detection pattern direction as shown in FIG. This detection pattern does not need to have the same shape on one printed circuit board. For example, the detection level should be increased immediately below the electrical parts where there is a high risk of smoke and fire, and the detection level should be increased in other low-risk areas. You can also lower it.

As described above, in the liquid leakage detection method for electric parts according to the present invention, the liquid leakage detection level can be made variable according to the need of the apparatus by changing the shape of the detection pattern directly below the electric parts. . Further, the number of detection patterns is not limited to one on one printed circuit board, and many wirings are
The detection level may be changed according to the risk of smoke emission in the wiring process.

As described above, in this embodiment, the electrolytic solution leaking from the aluminum electrolytic capacitor is monitored by detecting the voltage of the detection pattern, and a plurality of detection patterns are mounted on the substrate with one detection pattern. It is possible to easily detect all the abnormalities of the aluminum electrolytic capacitor that have been generated, and prevent serious troubles such as smoking and ignition in the device. That is, in the liquid leakage detecting method for an electric component according to the present invention, a liquid leakage detecting pattern is provided immediately below a mounting position of an electric component containing a conductive liquid on a printed circuit board, and the detection pattern is used. The voltage is fixed so that the voltage of the
Liquid leakage can be easily detected by monitoring the voltage fluctuation of the battery with the detection circuit. Further, when the liquid leakage is detected, for example, the power supply to the device can be stopped, and the risk of smoking and ignition can be prevented. Especially in the case of civilian equipment, if smoke is generated even if the heat does not reach the point of ignition, the user may be afraid of the risk of ignition and the reliability of the equipment and the manufacturer may be significantly reduced. The invention is able to detect leaks prior to smoke generation.

[0021]

As described above, the liquid leakage detection method according to the present invention can detect the liquid immediately below the electric component when the liquid leaks from the electric component containing the conductive liquid inside the aluminum electrolytic capacitor mounted on the printed circuit board. By monitoring the potential that the conductive liquid contacts the wired detection pattern and changes,
It is possible to detect liquid leakage from electric parts. Further, in the present method, the detection conductive pattern is arranged in a shape that covers the periphery of the terminal of the electric component in a position directly below the electric component in a non-contact manner, so that even if the liquid leakage is small, the liquid leakage can be easily detected. In addition, the gap between the leak detection conductive pattern and the terminal of the electric component is narrowed to increase the leak detection level, and the gap is widened to lower the leak detection level. The leak detection level can be set arbitrarily according to the risk of smoke / ignition. With these, the liquid leakage detection method according to the present invention can prevent disconnection of the wiring pattern, smoke, and fire accidents when a failure occurs.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a printed circuit board to which a liquid leakage detection method for an electric component according to an embodiment of the present invention is applied.

FIG. 2 is a diagram for explaining an example of a terminal of an aluminum electrolytic capacitor on a printed circuit board and a detection pattern for detecting liquid leakage.

FIG. 3 is a diagram for explaining a dimensional relationship between a terminal of an aluminum electrolytic capacitor and a detection pattern.

[Explanation of symbols]

1 ... Aluminum electrolytic capacitor, 2 ... Detection pattern, 3 ...
Anode side pattern, 4 ... Cathode side pattern, 5 ... Printed circuit board, 6A, 6B ... Wind comparator, 7 ... Logic IC, 8 ... Detection circuit, R1 to R5 ... Resistors.

Claims (3)

[Claims] 1. A liquid leakage detection method for an electric component, which detects liquid leakage from an electric component containing a conductive liquid mounted on a printed circuit board, wherein terminals of the electric component are electrically conductive wiring patterns on the printed circuit board. The conductive liquid leaked from the electrical component is connected to the wiring pattern, and a leak detection pattern that changes the potential when the conductive liquid leaked from the electrical component comes into contact with near the wiring pattern, and the conductive liquid leaked from the electrical component leaks. When a detection pattern and an electric component terminal are short-circuited, a failure is detected when the potential of the conductor fluctuates. 2. The leak detection method for an electric component according to claim 1, wherein the detection conductive pattern is arranged in a shape to cover the periphery of the terminal of the electric component in a position directly below the electric component in a non-contact manner. 3. The leak detection conductive pattern and the terminal of the electric component are narrowed to increase the leak detection level, or the gap is increased to lower the leak detection level. A method for detecting leakage of an electric component according to claim 1 or 2.