JP2003249424A - Selecting method of laminated capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a screening method of a laminated capacitor to preventing shipping of a capacitor defective in electrostatic capacity or in dielectric loss at a voltage withstanding test or an insulation resistance measurement. <P>SOLUTION: A prescribed DC voltage is applied to a laminated capacitor to measure the insulation resistance. After that the electrostatic capacity and the dielectric loss are measured. As a result of the measurement of these characteristics, the laminated capacitor with a measured value out of specifications is removed. Thus, a voltage is not applied after the measurement of the electrostatic capacity and the dielectric loss so that a defective capacitor is not revealed additionally. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of selecting a multilayer capacitor, and more particularly to a method of selecting a multilayer capacitor for measuring characteristics of the multilayer capacitor and removing defective products.

[0002]

2. Description of the Related Art A multilayer capacitor is provided with a plurality of internal electrodes inside a substrate, and the ends of the internal electrodes are joined and electrically connected to external electrodes formed on the surface of the substrate.
In recent years, the thickness of the internal electrode has become extremely thin, and the area of bonding with the external electrode has also become smaller. If the connection between the internal electrode and the external electrode is not sufficient, there arises a problem that the equivalent series resistance becomes large, the insertion loss becomes large, and a predetermined capacitance cannot be obtained. These defective products must be reliably removed before the product is shipped.

As a method for removing a defective product due to a defective connection between the internal electrode and the external electrode, for example, Japanese Patent Laid-Open No. 2000-1
There is a method disclosed in No. 24088. in this way,
The rated AC voltage is applied to the multilayer capacitor to reveal the defective joints, and after discharge, the capacitance and insertion loss are measured to remove defective products.

[0004]

However, this Japanese Unexamined Patent Application Publication No.
In No. 000-124088, the insulation resistance is measured after measuring the capacitance and the insertion loss. To measure the insulation resistance, a DC voltage higher than the rated voltage is usually applied. Therefore, since the voltage is applied to the multilayer capacitor again, some of the capacitors, which have not been revealed by the previous application of the AC voltage, may newly have a defective connection. If the insulation resistance is satisfied, the newly defective joint will be a non-defective product, and will be shipped as it is, and the defective product cannot be reliably removed. Also, after measuring the capacitance, etc.,
Although a withstand voltage test is sometimes performed,
In this case as well, a similar problem arose.

Therefore, a main object of the present invention is to provide a method for selecting a multilayer capacitor which can surely prevent a multilayer capacitor having a defective capacitance or a defective dielectric loss from flowing out.

[0006]

The present invention comprises a step of preparing a multilayer capacitor, a step of applying a DC voltage to the multilayer capacitor to measure an insulation resistance, and a step of discharging an electric charge accumulated in the multilayer capacitor. And a step of measuring the capacitance and the dielectric loss of the multilayer capacitor whose electric charge has been discharged. In such a method of selecting a multilayer capacitor, after the step of measuring the capacitance and the dielectric loss of the multilayer capacitor, the step of removing the multilayer capacitor in which any one of the insulation resistance, the capacitance and the dielectric loss is out of the regulation is included. May be included. In addition, after the step of discharging the electric charge accumulated in the multilayer capacitor, the step of removing the multilayer capacitor whose insulation resistance is out of the regulation is included, and after the step of measuring the electrostatic capacitance and dielectric loss of the multilayer capacitor, A step of removing a multilayer capacitor whose capacitance or dielectric loss is out of regulation may be included.

Since the capacitance and the dielectric loss are measured after the DC voltage is applied to the multilayer capacitor, the multilayer capacitor in which the capacitance defect and the dielectric loss defect are caused by the application of the DC voltage is measured later. Can be found by. When a defective product is found as a result of each measurement, the defective product is removed, but the removal timing may be after all the measurements have been performed, or the defective product may be removed for each measurement. May be removed.

The above objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of the embodiments of the invention with reference to the drawings.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a flow chart showing an example of a method for selecting a multilayer capacitor according to the present invention. In this screening method, first, a multilayer capacitor is prepared. The multilayer capacitor 10 includes a base 12. The base 12 is formed by alternately laminating a plurality of dielectric layers 14 and internal electrodes 16. Adjacent ones of the internal electrodes 16 are alternately drawn out to opposite end faces of the base 12. These internal electrodes 1
At the end of the substrate 12 from which the external electrode 6 is drawn, external electrodes 18,
20 is formed. The external electrodes 18 and 20 are, for example, C
Ni plating is applied on the baking electrode such as u.
It is plated or Sn-Pb plated.

External electrodes 18 of this multilayer capacitor 10,
As shown in step S30 of FIG. 1, a DC voltage having a rated voltage or higher is applied to the battery 20, and the battery is charged.
Then, as shown in step S32, the insulation resistance of the multilayer capacitor 10 is calculated by measuring and calculating the leakage current of the charged multilayer capacitor 10. After the insulation resistance is measured, the electric charge accumulated in the multilayer capacitor 10 is discharged as shown in step S34.

Multilayer capacitor 10 whose insulation resistance is measured
For the external electrode 1 as shown in step S36.
An AC voltage is applied between 8 and 20 to measure capacitance and dielectric loss. Then, as shown in step S38, the multilayer capacitor 10 in which any one of the insulation resistance, the capacitance, and the dielectric loss is out of the regulation is removed.

Further, as shown in step S40 of FIG. 3, a DC voltage is applied to the multilayer capacitor 10, the insulation resistance is measured in step S42, the insulation resistance is discharged in step S44, and then the insulation resistance is measured in step S46. However, the multilayer capacitor 10 which is out of the regulation may be removed. Thereafter, as shown in step S48, the capacitance and the dielectric loss of the multilayer capacitor 10 are measured as described above, and the multilayer capacitor 10 having the capacitance and the dielectric loss that are out of regulation is removed as shown in step S50. To be done. in this way,
The defective product may be removed collectively after all the characteristics of the multilayer capacitor 10 are measured, or may be removed for each characteristic failure after the measurement of each characteristic.

As described above, by eliminating the step of applying a voltage after measuring the electrostatic capacity and the insertion loss, a defective connection between the internal electrode and the external electrode due to the application of the voltage is not newly manifested, and the non-contact is prevented. It is possible to reliably prevent outflow of non-defective products. Further, unlike the prior art, the AC applying step and the discharging step for revealing the bonding failure are not necessary, and the steps can be simplified.

[0014]

[Example] As an evaluation sample, a multilayer ceramic multilayer capacitor having a rated voltage of 50 V was prepared. For this multilayer capacitor, defective products were sorted using the sorting method of the present invention and the conventional sorting method. The method shown in FIG. 3 was used as the selection method of the present invention. In addition, the conventional selection method is to measure the capacitance and dielectric loss of a multilayer capacitor to remove defective products whose characteristics are out of specification, and then apply a DC voltage to the multilayer capacitor for insulation. The method of measuring the resistance and removing defective products whose insulation resistance is out of specification was adopted.

In these selection methods, an AC voltage of 50 V was applied to the multilayer capacitor in order to measure capacitance and dielectric loss. Also, for the measurement of insulation resistance,
The DC voltage was changed and applied. Then, for each applied voltage, the outflow rate of defective capacitance and the outflow rate of defective dielectric loss were examined, and the results are shown in Table 1. Regarding the outflow rate of defective capacitance and the outflow rate of defective dielectric loss, a defective product was found by conducting a high temperature load test using acceptable products for all characteristics, and then measuring the electrostatic capacitance and dielectric loss. The percentage of things is shown.

[0016]

[Table 1]

As can be seen from Table 1, in the case of adopting the conventional selection method, a capacitance defect was found by applying a DC voltage of 200 V or more. Moreover, a dielectric loss defect was discovered by applying a DC voltage of 25 V or more. On the other hand, when the screening method of the present invention was adopted, neither electrostatic capacity failure nor dielectric loss failure was found. In the conventional sorting method, this is
Finally, because the insulation resistance of the multilayer capacitor was measured,
It is considered that this is because the connection between the internal electrode and the external electrode was newly cut due to the application of the DC voltage at that time, which flowed out. On the other hand, in the screening method of the present invention, since the insulation resistance is measured first, a defect caused by the application of the DC voltage is found to be defective in the subsequent measurement of capacitance and dielectric loss, It is considered that this is because it has been removed and no new defects will occur thereafter.

In this way, the insulation resistance is measured before measuring the capacitance and dielectric loss of the multilayer capacitor.
Since the rated voltage or a voltage higher than the rated voltage is not applied thereafter, it is possible to reliably prevent defective products from flowing out, and it is possible to improve the reliability of the multilayer capacitor.

[0019]

According to the present invention, the DC voltage application and the voltage application such as the withstand voltage for measuring the insulation resistance are all completed before the measurement of the electrostatic capacity and the dielectric loss, so that the characteristic failure is caused. It is possible to reliably prevent the outflow of a monolithic capacitor that has a problem.

[Brief description of drawings]

FIG. 1 is a flow chart showing an example of a method for selecting a multilayer capacitor of the present invention.

FIG. 2 is an illustrative view showing an example of a laminated ceramic laminated capacitor to which the screening method of the present invention is applied.

FIG. 3 is a flowchart showing another example of the method for selecting a multilayer capacitor of the present invention.

[Explanation of symbols]

10 Multilayer ceramic multilayer capacitors 12 Base 14 Dielectric layer 16 internal electrodes 18 External electrode 20 external electrodes

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2G028 AA01 AA02 BB06 CG01 CG03                       CG07 CG10 DH03 DH04 JP03                 2G036 AA04 AA20 AA27 BB02 CA05                 5E082 AA01 AB03 BC14 EE04 MM31                       MM32 MM35 MM37

Claims (3)

[Claims] 1. A step of preparing a multilayer capacitor, a step of applying a DC voltage to the multilayer capacitor to measure an insulation resistance, a step of discharging an electric charge accumulated in the multilayer capacitor,
And a method of selecting a multilayer capacitor, which comprises the steps of measuring the capacitance and the dielectric loss of the multilayer capacitor whose electric charge has been discharged. 2. A step of removing the multilayer capacitor in which any one of the insulation resistance, the electrostatic capacitance and the dielectric loss is out of the regulation, after the step of measuring the electrostatic capacitance and the dielectric loss of the multilayer capacitor. Item 1. A method for selecting a multilayer capacitor according to Item 1. 3. A step of removing the multilayer capacitor whose insulation resistance is out of regulation after the step of discharging the electric charge accumulated in the multilayer capacitor, and measuring capacitance and dielectric loss of the multilayer capacitor. The method for selecting a multilayer capacitor according to claim 1, further comprising a step of removing the multilayer capacitor whose capacitance or dielectric loss is out of regulation after the step of performing.