JP2003100573A - Method for releasing polarization of capacitor and method for measuring and selecting capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that a long time and a large-scale device are required in conducting batch processing using an oven to heat a capacitor and thus release the polarization of a dielectric of the capacitor, which has been caused by a withstand voltage test under the impression of DC voltage on the capacitor. SOLUTION: A high frequency voltage is impressed on the capacitor 1 from a high frequency power source 5 through terminal electrodes 3, 4. As a result, the capacitor 1 is allowed to be in the state of self-heating, which then allows to release the polarization of the dielectric 2 in a short time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for depolarizing a capacitor and a method for selecting a characteristic of a capacitor, and more particularly to an improvement for enabling depolarization processing in a shorter time.

[0002]

2. Description of the Related Art Before shipping a capacitor such as a monolithic ceramic capacitor, a withstand voltage test is performed to measure the withstand voltage characteristic of the capacitor. In this withstand voltage test, a DC voltage is applied to the capacitor.

However, the application of the above-mentioned DC voltage causes the dielectric substance provided in the capacitor to be in a polarized state, which causes a decrease in the electrostatic capacitance provided by the capacitor.

In order to recover the decrease in capacitance as described above, it is necessary to release the polarization state introduced into the dielectric.

Therefore, conventionally, the capacitor after performing the withstand voltage test is put in an oven and heated by batch processing to release the polarized state. During the heat treatment in the oven, a temperature exceeding the Curie point of the dielectric, for example, a temperature of about 150 ° C. is applied for about 30 minutes.

[0006]

However, when the polarization release treatment is performed by heating in the oven as described above, it takes a relatively long time, for example, 30 minutes, and a relatively large-scale device such as an oven. Need.

Further, Japanese Patent Laid-Open No. 2000-12369 describes a technique of irradiating a condenser with a laser beam to release the polarization state in a short time. However, when this technique is applied, a relatively large-scale device for irradiating laser light is required, and further, it is necessary to irradiate the condenser with laser light with high precision.

Therefore, it is desired that the polarization release treatment can be achieved in a shorter time, with higher accuracy and with a simpler device.

Therefore, an object of the present invention is to provide a method for depolarizing a capacitor, which can satisfy the above-mentioned demand, and a method for measuring and selecting a capacitor, which is carried out by applying the method for depolarizing the capacitor. is there.

[0010]

In order to solve the above-mentioned technical problems, a method of releasing polarization of a capacitor according to the present invention provides a dielectric in a polarized state and a capacitance formed in association with the dielectric. The method is characterized by including a step of preparing a capacitor having a terminal electrode for taking out and a step of causing the capacitor to self-heat by applying a high frequency voltage to the capacitor via the terminal electrode.

In the polarization releasing method according to the present invention described above, the applied high frequency voltage is 40 kHz to 400 kHz.
It is preferable to have frequencies in the frequency range in the range of Hz.

Further, it is preferable that the applied high frequency voltage has a frequency lower than the resonance frequency of the capacitor.

The polarization releasing method according to the present invention is particularly advantageously applied to a capacitor after carrying out a withstand voltage test under application of a DC voltage.

The present invention also measures withstand voltage characteristics,
Based on the results, it is also directed to a method for screening capacitors. This capacitor measurement / selection method is performed by first performing a withstand voltage test on a capacitor under application of a DC voltage, and then applying a high frequency voltage to the capacitor via a terminal electrode to cause the capacitor to self-heat. It is characterized by having.

[0015]

1 is a view for explaining a method of depolarizing a capacitor according to an embodiment of the present invention.

In FIG. 1, a capacitor 1 is shown. Capacitor 1 is, for example, a monolithic ceramic capacitor, and includes dielectric 2 and terminal electrodes 3 and 4 for taking out electrostatic capacitance formed in association with dielectric 2. This capacitor 1 is, for example, one that has been subjected to a withstand voltage test under application of a DC voltage, and therefore the dielectric 2 is in a polarized state.

In order to release the polarization of the dielectric 2, a high frequency power source 5 is prepared as shown in FIG. High frequency power 5
Has output terminals 6 and 7 for applying a high frequency voltage to the capacitor 1.

In performing the polarization release process of the dielectric 2 provided in the capacitor 1, the output terminals 6 and 7 are brought into electrical contact with the terminal electrodes 3 and 4 of the capacitor 1, respectively. A high frequency voltage from the power source 5 is applied to the capacitor 1 via the terminal electrodes 3 and 4. When the high frequency voltage is applied, the capacitor 1 self-heats due to the current flowing through the capacitor 1 and the equivalent series resistance of the capacitor 1. As a result of this self-heating, when the temperature of the dielectric 2 exceeds the Curie point, the polarization state brought to the dielectric 2 is released, and the electrostatic capacitance of the capacitor 1 is restored.

The high frequency voltage applied as described above is
For example, 20 to 100 Vrms is selected. in this case,
Within 10 seconds, the temperature of capacitor 1 is 150 ℃
Rise to a degree.

The applied high frequency voltage is 40 kHz.
It is preferable to have a frequency within the frequency range of z-400 kHz. When the frequency of the applied high-frequency voltage becomes high, the current flowing through the capacitor 1 becomes large and the temperature of the capacitor 1 rapidly rises, which makes temperature control difficult.

More specifically, the temperature of the capacitor 1 is set to 15
When increasing the temperature to about 0 ° C., the frequency of the applied high frequency voltage is preferably selected from the frequency range of 40 kHz to 400 kHz. When the frequency of the high frequency voltage exceeds 400 kHz, it becomes difficult to control the temperature of the capacitor 1, and when it becomes 700 kHz or more, the temperature control becomes more difficult.

Further, it is preferable that the applied high frequency voltage has a frequency equal to or lower than the resonance frequency of the capacitor 1. Thereby, the self-heating of the capacitor 1 can be more easily generated.

The high frequency voltage may have a sine wave or a rectangular wave.

FIG. 2 is for explaining a method for measuring and selecting capacitors according to one embodiment of the present invention, and schematically shows the steps carried out in the measuring and selecting machine 8.

Referring to FIG. 2, in the measuring and sorting machine 8,
First, the step 9 of taking in the capacitor to be measured is carried out.

Then, a withstand voltage test step 10 is performed on the capacitor under application of a DC voltage.

Next, a high frequency voltage applying step 11 is carried out on the capacitor which has undergone the withstand voltage test. At this time, the output terminal electrically contacting the terminal electrode of the capacitor may also serve as the output terminal used for applying the DC voltage in the withstanding voltage test step 10 described above.

Next, a take-out step 12 for taking out the capacitor is carried out. In the take-out step 12, the capacitors are taken out while distinguishing between those judged as good products and those judged as defective products as a result of the withstand voltage test in the withstand voltage test process 10.

As described above, the frequency of the high frequency voltage applied when the capacitor 1 self-heats to release the polarization of the dielectric 2 is 40 kHz to 400 kHz.
In order to prove that the range is preferably set to, the high-frequency voltage is applied under some conditions as shown in Table 1 below, and the application time until reaching 150 ° C. is obtained. As shown, the temperature rising curve under each condition was obtained.

[0030]

[Table 1]

In Table 1, "frequency" indicates the frequency of the applied high frequency voltage, and "current" indicates the current flowing through the capacitor during the application of the high frequency voltage.

In Table 1, the "voltage applied to the capacitor" and the "voltage of the power supply" are different from each other.
This is because the booster circuit is interposed between the high frequency power supply and the capacitor.

Further, Table 1 is provided with a column of "reference drawing", and the temperature rising curve under each condition shown in Table 1 is shown in FIG.
(A)-(c), FIG. 4 (a) and (b), and FIG.
It is clarified which of (a) and (b) corresponds.

As shown in Table 1 and FIGS. 3 to 5,
In any of the conditions 1 to 7, the temperature of the capacitor is 150 ° C within 3 seconds after applying the high frequency voltage.
Has reached.

However, what should be particularly noted is the temperature rising curve shown in FIGS.

Condition 1 in which the frequency of the high frequency voltage applied to the capacitor is in the range of 40 kHz to 400 kHz,
2, 3, 4 and 5, respectively, FIG.
As shown in (b), (c), FIG. 4 (a), and (b), the temperature rise curve has a comparatively gentle shape around 150 ° C., and temperature control is relatively easy to perform. I'm giving.

On the other hand, under the conditions 6 and 7 in which the frequency of the high-frequency voltage applied to the capacitor exceeds 400 kHz, as shown in FIGS. 5 (a) and 5 (b), respectively, the temperature around 150 ° C. The temperature rise curve has a large change and is difficult to control. Further, under these conditions 6 and 7, the self-heating of the capacitor is too large, so that the capacitor may be burnt out.

When the frequency of the high frequency voltage applied to the capacitor is less than 40 kHz, the capacitor 10
A voltage exceeding 0 Vrms is applied, which may damage the capacitor, which is not preferable.

[0039]

As described above, according to the method of depolarizing the capacitor of the present invention, by applying a high frequency voltage to the capacitor, the capacitor self-heats, thereby releasing the polarized state of the dielectric. Therefore, the temperature of the capacitor can be raised to a desired temperature in a shorter time as compared with the case of relying on external heating such as the case of using an oven. Therefore, the time required for the polarization release processing of the capacitor can be shortened.

Further, it is possible to reduce the size and space of the apparatus as compared with the case of using a conventional apparatus such as an oven.

Further, according to the present invention, since the self-heating of the capacitor is utilized, it is possible to minimize the influence of the heat generation on the external surrounding environment, which is a concern in the case of an external heating system such as an oven. it can.

In the capacitor depolarization method according to the present invention, when the frequency of the high frequency voltage applied to the capacitor is selected in the range of 40 kHz to 400 kHz, the temperature raised by the self-heating of the capacitor can be easily controlled. it can. Therefore, it is possible to simplify the process control when performing the polarization release processing of the capacitor.

According to the method of measuring and selecting a capacitor according to the present invention, a high-frequency voltage is applied to the capacitor after a withstand voltage test is performed on the capacitor so that the capacitor self-heats. Therefore, it is possible to efficiently proceed from the withstand voltage test to the polarization release process in a series of steps, and the time can be shortened compared to the case where the withstand voltage test and the polarization release process are performed under different process flows. And workability can be improved.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a method of depolarizing a capacitor according to an embodiment of the present invention.

FIG. 2 is a view for explaining a method of measuring and sorting capacitors according to an embodiment of the present invention, and is a diagram sequentially showing steps performed in a measuring and sorting machine 8.

3A is a temperature rise curve of a capacitor under the condition 1 shown in Table 1, FIG. 3B is a temperature rise curve under the condition 2 of FIG. 3, and FIG. The temperature rising curve in the case is shown.

FIG. 4 is a diagram corresponding to FIG. 3, in which (a) shows a temperature rising curve under the condition 4 shown in Table 1, and (b) shows a temperature rising curve under the same condition 5;

FIG. 5 is a view corresponding to FIGS. 3 and 4, and (a)
Shows the temperature rise curve under the condition 6 shown in Table 1,
Similarly, (b) shows a temperature rising curve under the condition 7.

[Explanation of symbols]

1 capacitor 2 dielectric 3,4 terminal electrode 5 high frequency power supply 8 measuring and sorting machine 10 Withstanding voltage test process 11 High-frequency voltage application process

Claims (5)

[Claims] 1. A step of preparing a capacitor having a dielectric in a polarized state and a terminal electrode for taking out a capacitance formed in relation to the dielectric, and a high frequency to the capacitor via the terminal electrode. A method of depolarizing a capacitor, which comprises causing the capacitor to self-heat by applying a voltage. 2. The applied high frequency voltage is 40 kH
The method of depolarizing a capacitor according to claim 1, having a frequency within a frequency range of z to 400 kHz. 3. The capacitor depolarization method according to claim 1, wherein the applied high frequency voltage has a frequency equal to or lower than a resonance frequency of the capacitor. 4. The method of depolarizing a capacitor according to claim 1, wherein the capacitor is after a withstand voltage test under application of a DC voltage. 5. A method for measuring a withstand voltage characteristic and selecting a capacitor based on the result, wherein first, a withstand voltage test is performed on the capacitor under application of a direct current voltage, and then, A method for measuring and selecting a capacitor, comprising the steps of causing the capacitor to self-heat by applying a high-frequency voltage to the capacitor via the terminal electrode.