JP2003059784A - Method for sorting multilayer ceramic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for sorting multilayer capacitors in which even a rejectable product having a microdefect internally can be sorted in a short time. SOLUTION: In the first sorting step, a voltage several times as high as the rated voltage of a multilayer ceramic capacitor being sorted is applied for a specified time under a high temperature exceeding a working temperature range and then the insulation resistance is measured. In the second sorting step, a voltage within the rated voltage is applied for a shorter time than the applying time in the first sorting step at the temperature in the first sorting step and then the insulation resistance is measured again. A new reference insulation resistance higher than that in the first sorting step is employed in the second sorting step.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for selecting a laminated ceramic capacitor, and more particularly to a method for selecting a laminated ceramic capacitor by measuring an insulation resistance value by applying a high temperature and high voltage.

[0002]

2. Description of the Related Art In a monolithic ceramic electronic component, there is a strong demand for miniaturization and weight reduction of the electronic component itself due to miniaturization and weight reduction of a device in which the monolithic ceramic electronic component is mounted. For example, in a monolithic ceramic capacitor, in order to increase the capacity while reducing the size, the thickness of the ceramic layer between the internal electrodes is reduced.

However, as the ceramic layer becomes thinner, the probability that agglomeration of impurities, voids, etc. will occur in the ceramic layer during the manufacturing process of the ceramic capacitor, and the initial failure of the capacitor is likely to occur, resulting in reduced reliability. There was something to do. For defective products with these defects, the insulation resistance value is measured by applying the rated voltage or a voltage several times higher than that at room temperature for several seconds, and the product whose insulation resistance value does not reach the standard is regarded as a defective product. It was detected and sorted.

[0004]

However, the thinner the ceramic layer between the internal electrodes, the lower the reliability of the monolithic ceramic capacitor, even if there are slight structural defects in the ceramic layer. The probability increases. Such a slight structural defect is usually difficult to detect even if the insulation resistance value of the monolithic ceramic capacitor is measured and sorted at room temperature. Could be delayed.

Therefore, as in Japanese Patent Laid-Open No. 2000-164471, a high voltage is applied to a monolithic ceramic capacitor at a high temperature (for example, at 105 ° C., 30 V which is about three times the rated voltage).
Voltage is applied for 5 minutes) to cause destruction and deterioration of the existing defective portion to reveal the defect, and then the insulation resistance value is measured and selected in that state.

This sorting method can detect fine defects as compared with sorting at room temperature, but in a high temperature and high voltage environment, the insulation resistance value of a non-defective product also decreases, so that the defects are about to deteriorate. In some cases, the difference between the insulation resistance value of a defective product and the defective product becomes small, and it may be difficult to distinguish between a good product and a defective product.

An object of the present invention is to provide a method of selecting a multilayer capacitor which can select a defective product having a minute defect therein in a shorter time.

[0008]

According to the present invention, a defective ceramic is selected by applying a first voltage, which is several times larger than the rated voltage, to a laminated ceramic capacitor at high temperature and measuring an insulation resistance value. After deteriorating the defects inherent in the monolithic ceramic capacitor, a second voltage lower than the first voltage is applied at a high temperature to measure an insulation resistance value to select defective products. The multilayer ceramic capacitors are selected in preparation. Thereby, the monolithic ceramic capacitors are selected under the two conditions.

Further, according to the present invention, the value obtained by dividing the second voltage by the second reference insulation resistance value is 1/10 or more of the value obtained by dividing the first voltage by the first reference insulation resistance value. The second voltage is set so that the multilayer ceramic capacitors are selected. As a result, the applied voltage in the two sorting steps is greatly changed.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a method for selecting a multilayer ceramic capacitor according to the present invention will be described below.

The multilayer capacitor to be selected has a ceramic sintered body made of a dielectric ceramic such as barium titanate ceramics. In the multilayer capacitor,
It has a plurality of internal electrodes facing each other, and these are arranged so as to overlap in the thickness direction with a ceramic layer interposed therebetween. The internal electrodes are formed by screen-printing a conductive paste on the surface of a ceramic such as a ceramic green sheet to be a ceramic layer and firing it. These internal electrodes are alternately drawn out to two opposing side surfaces of the ceramic sintered body, and external electrodes are formed so as to cover the opposing side surfaces. The external electrodes are formed by a method such as applying a conductive paste and firing.

As a method for selecting defective products of such a monolithic ceramic capacitor, the following two kinds of selection are carried out successively.

As the first selection, a voltage about 10 times the rated voltage of the selected monolithic ceramic capacitor is applied for a certain period of time at a high temperature exceeding the operating temperature range, and the insulation resistance value at this time is measured. . The insulation resistance value can be obtained by measuring a minute current (leakage current) generated when a voltage is applied. When the measured insulation resistance value is lower than the preset first reference insulation resistance value, the insulation resistance value of the measured product is lower, the product is selected as a defective product.

Next, after discharging the voltage charged in the first screening, as a second screening, the voltage within the rated voltage is the temperature in the first screening, and is longer than the application time in the first screening. Apply it for a short time and measure the insulation resistance again. In this selection, a new reference insulation resistance value that is higher than the preset insulation resistance value that is the reference for the first selection is used. Here, if it is lower than the insulation resistance value that is the reference for the second selection, it is selected as a defective product.

With such a structure, in the first screening, the multilayer capacitors are primarily screened, and in the first screening, high stress of high temperature and high pressure is applied to the multilayer capacitors, so that the multilayer capacitors are applied to the multilayer capacitors. It causes the destruction and deterioration of the internal minute defects.

Here, by carrying out the second selection, minute defects are surfaced and the selection becomes easy.

Since the first screening is carried out at a high temperature, the insulation resistance value of the good product is also lowered, so that a latent defect product containing minute defects whose defect portions are not so deteriorated due to high stress. The difference between and is small and it is difficult to make a distinction. However, if the applied voltage is lowered while keeping the temperature as it is, the insulation resistance value of a good product increases. Therefore, the difference in the insulation resistance value between the non-defective product and the potentially defective product is widened, and the difference in the insulation resistance value can be discriminated even with a slight difference in the internal structure.

Therefore, the second screening can be performed by measuring the insulation resistance value at the same temperature as the first screening and at a voltage lower than the applied voltage in the first screening, for example, a voltage close to the rated voltage. Even if it does not have such a large defect, it is possible to reliably detect the difference from the insulation resistance value of a good product.

Next, the results of the experiment according to this embodiment will be described below.

The monolithic ceramic capacitor used in the experiment was one in which a nickel internal electrode was formed on a dielectric layer of barium titanate, the rated voltage was 6.3 V, and the operating temperature range was -25 ° C to 85 ° C. is there.

In this experiment, this laminated ceramic capacitor was selected under the following four conditions, and a reliability test was performed on the selected good product to confirm whether or not there is a defective product in the good product after selection. ing. Here, the condition of the reliability test is that a voltage of 30 V is applied for 6 hours at a temperature of 125 ° C., and thereafter, the insulation resistance value of the laminated ceramic capacitor was measured to judge whether it was good or bad.

For selection, the current is applied under conditions of a temperature of 125 ° C., an applied voltage of 65 V and an applied time of 60 seconds, and the insulation resistance value in this state is measured. I am trying. In the selection of No. 1, after performing the selection under the same conditions as the selection in -1, the products selected as non-defective products are energized under the conditions of -2 at a temperature of 125 ° C, an applied voltage of 45 V, and an application time of 10 seconds, If the insulation resistance value in this state is 1.5 MΩ or more, it is considered a good product. The selection of
After sorting under the same conditions as the sorting in -1, the sorted products as good products are energized at -2 in temperature of 125 ° C., applied voltage of 25 V, and applied time of 10 seconds. If the insulation resistance value is 4.0 MΩ or more, it is regarded as a good product. In the selection of No. 1, after performing the selection under the same conditions as the selection in -1, the products selected as non-defective products are energized under the conditions of -2 at a temperature of 125 ° C, an applied voltage of 10 V, and an application time of 10 seconds, If the insulation resistance value in this state is 10.0 MΩ or more, it is determined as a good product. The results are shown in Table 1.

[0023]

[Table 1]

As shown in Table 1, once selected under high temperature and high voltage conditions, a voltage close to the rated voltage is applied at high temperature and selected according to a high insulation resistance value. The detection rate of latent defects is improved as compared with the case of selecting only by itself.

Further, the lower the voltage of the second selection and the higher the insulation resistance standard, the higher the defect detection rate.

As described above, after the first selection under the high temperature / high voltage condition, the selection under the high temperature / low voltage (voltage lower than the first time and close to the rated voltage) condition, The detection rate can be improved.

In this embodiment, the above-mentioned specific selection conditions are obtained by using the above-mentioned laminated ceramic capacitor. These conditions vary depending on the shape, electrical characteristics, reliability characteristics, etc. of the monolithic ceramic capacitor, and similar selection can be performed by experimentally obtaining the conditions suitable for each monolithic ceramic capacitor in advance. it can.

In this embodiment, the high temperature condition is 1
Although a high voltage was applied at 25 ° C., if the temperature is higher than room temperature (about 25 ° C.), the deterioration is higher than that at room temperature, so the high temperature in the present application indicates a temperature higher than room temperature.
When considering the time under high temperature and high voltage conditions, 85 ° C
A temperature of about 180 ° C is desirable.

[0029]

According to the present invention, a first voltage is applied to a monolithic ceramic capacitor at a high temperature to measure an insulation resistance value to select a defective product, and a defect inherent in the monolithic ceramic capacitor is deteriorated. First after high temperature
The multi-layer ceramic capacitor is selected by the two selection processes of applying a second voltage lower than the voltage of 1 to measure the insulation resistance value and selecting defective products. As a result, defective products including defects that have been surfaced in the first screening are detected from defective products including internal defects and non-defective products, and inherent defects that cannot be sorted in the first screening in the second screening. It is possible to detect defective products including.

According to the present invention, the value obtained by dividing the second voltage by the second reference insulation resistance value gives the first voltage as the first value.
The multilayer ceramic capacitors are selected by setting the second voltage so as to be 1/10 or more of the value divided by the reference insulation resistance value of. In this way, by increasing the difference in applied voltage between the two sorting steps, defective products having surfaced defects can be detected more reliably and easily in the second sorting.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshikazu Takagi             2-10-10 Tenjin, Nagaokakyo, Kyoto Stock             Murata Manufacturing Co., Ltd. F term (reference) 5E082 AB03 BC40 FG26 MM19 MM35

Claims (2)

[Claims] 1. A method for selecting a laminated ceramic capacitor in which a plurality of internal electrodes are laminated via ceramic layers, wherein a first voltage having a magnitude several times higher than a rated voltage is applied to the laminated ceramic capacitor at a high temperature. Insulation resistance value is applied to measure the insulation resistance value, and a monolithic ceramic capacitor whose insulation resistance value is lower than the first reference insulation resistance value is selected as a defective product, and defects inherent in the monolithic ceramic capacitor are deteriorated. Later, a second voltage lower than the first voltage at the high temperature
Voltage is applied to measure the insulation resistance value, and the insulation resistance value of the insulation resistance value is lower than the second reference insulation resistance value is selected as a defective product. 2. A second leakage current value obtained by dividing the second voltage by the second reference insulation resistance value is a first leakage current value obtained by dividing the first voltage by the first reference insulation resistance value. The method for selecting a monolithic ceramic capacitor according to claim 1, wherein the second voltage is set so as to be 1/10 or more of a leakage current value.