JPH0640118B2 - Method of measuring leakage current of capacitors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] Regarding a method for measuring a leakage current in a capacitor test, for the purpose of simplifying a measuring device and improving work efficiency, when measuring a leakage current, a measured capacitor 4 is It is connected to the test power supply 1 and the current detection circuit 2 via the probe 7 and the changeover switch 8, and after measuring the leakage current of the capacitor 4 to be measured by the current detection circuit 2, it is accumulated in the capacitor 4 to be measured at the time of measuring the leakage current. The generated electricity is discharged through the probe 7 and the changeover switch 8, the current value is detected, and the contact state between the capacitor 4 to be measured and the probe 7 when the leakage current is measured is detected from the discharge current value. To configure.

[Industrial application field]

The present invention relates to a method for measuring a leakage current in a capacitor test, and particularly to a method for measuring a leakage current that simplifies a measuring device and improves work efficiency.

In a capacitor used in combination with a semiconductor integrated circuit or the like, if the leakage current is large, the semiconductor integrated circuit may be destroyed, and it is extremely important to measure the leakage current in the manufacturing process. However, in the measurement of such leakage current, the lead terminal of the capacitor to be measured is connected to the test power supply or the current detection circuit via a probe, and even if the leakage current is not detected in the current detection circuit, for example, It cannot be determined whether the characteristics are excellent and cannot be detected, or the contact between the lead terminal and the probe is poor and cannot be detected. Therefore, it is desired to establish a measuring method capable of detecting the contact state of the probe as well as the leakage current.

[Conventional technology]

 FIG. 3 is a circuit diagram showing a conventional leakage current measuring method.

As shown in the figure, a conventional test current source 1, a current detection circuit 2, and a continuity determination circuit 3 are used to measure the leakage current, and the current detection circuit 2 is composed of, for example, an amplifier circuit 21 and an ammeter 22.
Test power supply 1 and current detection circuit 2 or continuity determination circuit 3
The capacitor 5 to be measured and the capacitor 4 to be measured are connected via a probe 5 and a switch 6 for switching the connection destination of the probe. As the probe 5, a multipolar probe in which two electrodes are in contact with the same lead terminal is also switched. As the switch 6, a multi-circuit switch capable of simultaneously switching the connection destinations of the electrodes of the other pole probe is used.

In the figure, all electrodes of the multi-pole probe 5 are connected to the current detection side, the test power supply 1 is connected to one lead terminal of the capacitor 4 to be measured, and the current detection is connected to the other lead terminal of the capacitor 4 to be measured. The circuit 2 is connected via the changeover switch 6 and the two electrodes of the multipolar probe 5, respectively. In this state, a test voltage is applied to the capacitor to be measured 4 and the leak current at that time can be measured.

When the changeover switch 6 is switched after measuring the leakage current of the capacitor to be measured 4, all electrodes of the multipolar probe 5 are connected to the continuity determination circuit 3. The continuity determination circuit 3 includes a continuity check circuit corresponding to each multipole probe 5, and when each electrode of the same multipole probe 5 is surely in contact with the lead terminal, the continuity check circuit 3 It is grounded through the electrode of the probe and the lead terminal. However, if any one of the electrodes is not in contact with the lead terminal, the continuity check circuit associated with the electrode is not grounded and the contact failure can be easily detected.

For example, if the leakage current cannot be detected in the above-mentioned leakage current detection and there is no abnormality in the contact between the probe and the lead terminal in the continuity determination, there is no problem in deciding that this capacitor to be measured is a good product, but in the continuity determination When an abnormality is found in the contact between the probe and the lead terminal, the contact state between the capacitor to be measured and the multipolar probe is checked, and the leak current is measured again.

[Problems to be solved by the invention]

However, in the conventional test method, a multipole probe is used, and the circuit configuration is complicated such as requiring a changeover switch capable of simultaneously changing multiple circuits, and if either one of the two electrodes is not in contact, There was a problem that the leakage current was measured again and the operating efficiency was extremely poor.

[Means for solving problems]

FIG. 1 is a circuit diagram showing the principle of the leakage current measuring method according to the present invention. Note that the same object is denoted by the same symbol throughout the drawings.

This problem is solved by paying attention to the fact that the contact state of the probe can be detected from the current value at the time of discharging the electricity accumulated in the capacitor to be measured when measuring the leakage current. That is, the above problem is that when measuring the leakage current, the measured capacitor 4 is connected to the test power supply 1 and the current detection circuit 2 via the probe 7 and the changeover switch 8, and the leakage of the measured capacitor 4 is caused by the current detection circuit 2. After measuring the current, the electricity stored in the capacitor to be measured 4 at the time of measuring the leakage current is discharged through the probe 7 and the changeover switch 8 to detect the current value, and the capacitor to be measured at the time of measuring the leakage current. This is solved by the method for measuring the leakage current of the capacitor according to the present invention, which detects the contact state between the probe 4 and the probe 7 from the discharge current value.

[Action]

In Fig. 1, after measuring the leak current of the capacitor to be measured by the current detection circuit, the electricity accumulated in the capacitor to be measured is discharged to detect the discharge current, and the contact state between the capacitor to be measured and the probe is detected from the discharge current value. By detecting, the probe to be brought into contact with the capacitor to be measured becomes a unipolar probe, the number of changeover switch circuits is reduced, the circuit configuration is simplified, and the contact between the lead terminal of the capacitor to be measured and the probe is made. As a result, the number of times of re-measurement of the leakage current is reduced and the work efficiency can be improved.

〔Example〕

The leakage current measuring method of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 2 is a circuit diagram showing an embodiment of the present invention.

In the leakage current measuring method according to the present invention, a test power supply 1 and a current detection circuit 2 are used as shown in FIG. 1, and one lead terminal of a capacitor 4 to be measured is connected to the test power supply 1 via a probe 7 and a changeover switch 8. The other lead terminal is connected to the current detection circuit 2 via the probe 7. In the figure, the changeover switch 8 is connected to the test power supply 1 side, and in such a case, a test voltage is applied to the capacitor 4 to be measured, and the leak current at that time can be measured by the current detection circuit 2.

When the changeover switch 8 is changed over after measuring the leakage current, the probe 7 which has been connected to the test power supply 1 until then is grounded via the resistor R, and the electricity stored in the capacitor 4 to be measured passes through the resistor R. After being discharged, the current detection circuit 2 detects the discharge current at that time.

The electricity discharged by switching the changeover switch 8 is the electricity applied to and accumulated in the capacitor 4 to be measured via the contact point between the probe 7 and the lead terminal when measuring the leakage current, and the electricity is stored in the probe 7 and the lead. The discharge current is always detected if the terminals are in good contact. On the other hand, when the probe 7 is not in contact with the lead terminal, electricity is not accumulated in the measured capacitor 4 when measuring the leakage current, and electricity is accumulated in the measured capacitor 4 before measuring the leakage current. However, no discharge current flows. In the case of poor contact, even if a discharge current flows, its value is extremely weak, so that it can be easily identified.

In the embodiment shown in FIG. 2, a discharge current detection circuit 9 is provided in addition to the test power supply 1 and the current detection circuit 2 in order to further stabilize the leakage current measurement and the contact state detection. That is, one lead terminal of the capacitor to be measured 4 is connected to the test power supply 1 via the probe 7 and the changeover switch 8, and the other lead terminal is connected to the current detection circuit 2 via the probe 7 and the changeover switch 8. The current detection circuit 2 is, for example, an amplifier circuit 21.
And current source 22. In the figure, the changeover switch 8 is connected to the test power supply 1 side and the current detection circuit 2 side. In such a case, the test voltage is applied to the capacitor 4 to be measured, and the leakage current at that time is measured by the current detection circuit 2. You can

When the changeover switch 8 is changed over after measuring the leak current, the probe connected to the test power supply 1 and the probe connected to the current detection circuit 2 are short-circuited via the photocoupler 91 of the discharge current detection circuit 9. The electricity stored in the measured capacitor 4 is discharged through the photocoupler 91. The discharge current detection circuit 9 is a photo coupler 91.
And a determination circuit 92, and this photo coupler 91
The determination circuit 92 determines whether the contact state between the capacitor 4 to be measured and the probe 7 is good or bad based on the output current of the.

After measuring the leakage current of the capacitor to be measured by the current detection circuit in this way, discharge the electricity accumulated in the capacitor to be measured to detect the discharge current, and check the contact state between the capacitor to be measured and the probe from the discharge current value. By detecting, the probe that contacts the capacitor to be measured becomes a unipolar probe, the number of changeover switch circuits is reduced and the circuit configuration is simplified, and the contact between the lead terminal of the capacitor to be measured and the probe is ensured. Therefore, the number of times of re-measurement of the leakage current is reduced, and the work efficiency can be improved.

〔The invention's effect〕

As described above, according to the present invention, it is possible to provide a leakage current measuring method that simplifies the measuring device and improves work efficiency.

[Brief description of drawings]

1 is a circuit diagram showing the principle of the leakage current measuring method according to the present invention, FIG. 2 is a circuit diagram showing an embodiment of the present invention, and FIG. 3 is a circuit diagram showing a conventional leakage current measuring method. is there. In the figure, 1 is a test power supply, 2 is a current detection circuit, 4 is a capacitor to be measured, 7 is a probe, 8 is a changeover switch, 9 is a discharge current detection circuit, 21 is an amplification circuit, 22 is an ammeter, 91 is a photocoupler, Denoted by 92 is a decision circuit.

Claims (1)

[Claims] 1. When measuring a leakage current, a capacitor to be measured (4) is connected to a test power supply (1) and a current detection circuit (2) through a probe (7) and a changeover switch (8), and a current is measured. After measuring the leakage current of the capacitor to be measured (4) by the detection circuit (2), the electricity accumulated in the capacitor to be measured (4) at the time of measuring the leakage current is transferred to the probe (7) and the changeover switch (8). ), The current value is detected, and the contact state between the measured capacitor (4) and the probe (7) when the leakage current is measured is detected from the discharge current value. Method for measuring leakage current of capacitors.