JP2005108946A - Failure detection method and failure-detecting apparatus of stacked ceramic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the failure detecting method of a stacked ceramic capacitor wherein a defective insulation layer can be specified accurately. <P>SOLUTION: In a stacked ceramic capacitor set as the application object of the failure detection method, a plurality of internal electrodes 36, 37 are embedded in layers in the inside of a dielectrics substrate 31. The internal electrodes 36, 37 are constituted, by electrically conducting to a pair of terminal electrodes 32, 33 which are applied to the external surface of the dielectrics substrate 31. When a failure is detected, the stacked ceramic capacitor is set under a temperature environment of at least 60°C and so ground that the ground surface perpendicular to the direction of lamination of the internal electrodes 36, 37 is produced, and the insulation resistance between the terminal electrodes 32-33 is measured. Poor insulation is detected by increase of measuring resistance value. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a failure detection method for a multilayer ceramic capacitor and a failure detection apparatus used in the failure detection method.

  Multilayer ceramic capacitors are manufactured by laminating a predetermined number of ceramic green sheets (unfired ceramic sheets) printed with internal electrode patterns, and then performing necessary steps such as laminating (heat compression integration), cutting, degreasing, and firing. The

  In this type of multilayer ceramic capacitor, in order to prevent the occurrence of defective products caused by defective insulation of the ceramic layer, it is necessary to identify the layer causing the defective insulation and reflect the result in the design and manufacture of the product. is there.

  Various methods have been proposed so far for identifying a poor insulation layer. For example, Patent Document 1 discloses a method of identifying a poor insulation layer by polishing a laminated ceramic capacitor using a polishing apparatus, measuring an insulation resistance (IR) between both terminal electrodes, and detecting an increase in the measured resistance value. Is disclosed. In order to identify a poor insulation layer by such a method, it is necessary that the measured resistance value rises to produce a sufficiently significant difference.

  However, if the polishing of the multilayer ceramic capacitor and the measurement of the insulation resistance are performed in a room temperature (25 ° C.) environment, a sufficient significant difference cannot be obtained in the measured resistance value, and it is difficult to specify a poor insulation layer.

  Patent Document 2 discloses a technique for measuring an insulation resistance in a state where a multilayer ceramic capacitor is heated, and selecting and removing a product having an abnormal measurement resistance as a defective product. However, there is no mention of measuring the insulation resistance with polishing.

  Although Patent Document 3 describes that heating is performed at a temperature equal to or higher than the Curie temperature and equal to or higher than 125 ° C., IR and IR lifetime are predicted and determined from the relationship between the impedance phase angle and the frequency and phase angle. It does not disclose a technique for directly measuring IR. Furthermore, there is no mention of measuring the insulation resistance together with the polishing treatment.

Patent Document 4 discloses a technique of heating the insulation resistance value by applying a DC voltage to the Curie temperature or higher, and does not disclose a technique of measuring the insulation resistance in a heated state. Furthermore, there is no mention of measuring the insulation resistance together with the polishing treatment.
Japanese Patent Laid-Open No. 5-107291 JP-A-9-205037 JP 2000-260653 A JP 2002-168897 A

  An object of the present invention is to provide a method for detecting a defect of a multilayer ceramic capacitor capable of accurately specifying a defective insulation layer, and a defect detection device used in the defect detection method.

  In order to solve the above-described problems, the present invention is directed to a failure detection method and failure detection apparatus for a multilayer ceramic capacitor.

1. Defect detection method for multilayer ceramic capacitor The multilayer ceramic capacitor has a plurality of internal electrodes embedded in a dielectric substrate, and the internal electrodes are a pair of terminals provided on the outer surface of the dielectric substrate. Conducted to the electrode.

  In detecting defects, the multilayer ceramic capacitor is placed in a temperature environment of 60 ° C. or higher, and the multilayer ceramic capacitor is polished so as to produce a polished surface perpendicular to the stacking direction of the internal electrodes, and between the terminal electrodes. Measure the insulation resistance and detect insulation failure by increasing the measured resistance value.

  As described above, when the multilayer ceramic capacitor is polished so as to produce a polished surface perpendicular to the stacking direction of the internal electrodes and the insulation resistance between the terminal electrodes is measured, the measured resistance value is measured when the polishing position reaches the poor insulation layer. Rises. In order to identify a poor insulation layer by such a method, it is necessary to increase the measured resistance value with a sufficiently significant difference.

  According to the experiments by the inventors, when the insulation resistance between both terminal electrodes of a multilayer ceramic capacitor is measured in a temperature environment of 60 ° C. or higher, the measurement is performed between a good insulation product and a poor insulation product of the multilayer ceramic capacitor. It was found that there was a significant difference in resistance value.

  Therefore, when the polishing of the multilayer ceramic capacitor and the measurement of the insulation resistance are performed in a temperature environment of 60 ° C. or higher, it is possible to cause a sufficiently significant difference in the increase in the measured resistance value accompanying the polishing. When the measured resistance value rises with a sufficiently significant difference, it is possible to clearly detect an increase in the measured resistance value, thereby accurately identifying a poor insulation layer.

2. Multilayer Ceramic Capacitor Defect Detection Device The multilayer ceramic capacitor defect detection device includes a polishing device, a heating means, and a resistance measurement device. In the multilayer ceramic capacitor, a plurality of internal electrodes are embedded in layers inside a dielectric substrate, and the internal electrodes are electrically connected to a pair of terminal electrodes provided on the outer surface of the dielectric substrate.

  The polishing apparatus polishes the multilayer ceramic capacitor so as to produce a polishing surface perpendicular to the stacking direction of the internal electrodes. The heating means gives a temperature environment of 60 ° C. or higher to the multilayer ceramic capacitor. The resistance measuring device measures an insulation resistance between the terminal electrodes of the multilayer ceramic capacitor.

  According to such a defect detection apparatus, the above-described defect detection method according to the present invention can be implemented.

  As described above, according to the present invention, it is possible to provide a failure detection method for a multilayer ceramic capacitor that can accurately identify an insulation failure layer, and a failure detection device used in the failure detection method.

  Other objects, configurations and advantages of the present invention will be described more specifically with reference to examples.

  A defect detection method according to the present invention will be described with reference to FIGS. First, referring to FIG. 1, a multilayer ceramic capacitor to which a defect detection method according to the present invention is applied is displayed as a cross-sectional view. In the illustrated multilayer ceramic capacitor, a plurality of internal electrodes 36 and 37 are embedded in a dielectric substrate 31 in layers. Two adjacent internal electrodes 36 and 37 face each other through a dielectric layer of 10 μm or less, for example. The internal electrodes 36 and 37 are made of, for example, Ni or Cu. The number of layers of the internal electrodes 36 and 37 varies depending on the required capacitance, and is several tens to several hundreds.

  The internal electrode 36 is electrically connected to the terminal electrode 32 of the pair of terminal electrodes 32 and 33 provided on the outer surface of the dielectric substrate 1, and the internal electrode 37 is electrically connected to the terminal electrode 33. The terminal electrodes 32 and 33 are provided on both end surfaces of the dielectric substrate 1 viewed in a direction parallel to the electrode surfaces of the terminal electrodes 32 and 33.

  In the multilayer ceramic capacitor having such a configuration, it is assumed that a defective insulation portion F is generated in the layer between the internal electrodes 36-37 as shown in the figure. In this case, the insulation failure of the multilayer ceramic capacitor is detected by confirming the resistance value between the terminal electrodes 32-33 with the insulation resistance meter 9 or the like.

  According to the steps of FIG. 1, it is possible to detect insulation failure of the multilayer ceramic capacitor, but it is not possible to identify the layer in which insulation failure has occurred. Accordingly, in the inspection step shown in FIG. 1, the failure detection method shown in FIGS. 2 to 3 is executed in order to identify the layer in which the insulation failure has occurred in the multilayer ceramic capacitor that has been determined to have insulation failure.

  FIG. 2 is a diagram showing a configuration of a defect detection apparatus used for carrying out the multilayer ceramic capacitor defect detection method according to the present invention. In the figure, reference numeral 1 denotes a polishing device, 2 denotes a resistance measuring device, and 3 denotes a multilayer ceramic capacitor to be inspected for defective products.

  The polishing apparatus 1 polishes the multilayer ceramic capacitor 3 so that a polishing surface perpendicular to the stacking direction of the internal electrodes 36 and 37 is generated. In other words, the polishing is performed so as to produce a polishing surface parallel to the electrode surfaces of the internal electrodes 36 and 37. Specifically, the polishing apparatus 1 includes a table 11 and a polishing tool 12. The table 11 is linearly fed in the direction of arrow a or b by a drive source such as a motor (not shown). A multilayer ceramic capacitor 3 is fixedly mounted on the table 11. In fixing the multilayer ceramic capacitor 3, the substrate 13 is disposed on the table 11, the substrate 13 is fixed on the table 11 by the fixtures 14 and 15, and the multilayer ceramic capacitor 3 is further mounted on the substrate 13. To fix. As a means for fixing the multilayer ceramic capacitor 3 to the substrate 13, solder or the like can be cited. Unlike the illustrated example, it can be fixed by embedding a multilayer ceramic capacitor in an epoxy resin or a pine or other adhesive.

  The polishing tool 12 is disposed above the table 11 and is driven to rotate as indicated by an arrow c so as to polish the multilayer ceramic capacitor 3. The polishing tool 12 has a structure in which a grindstone mounting portion 122 is provided at the tip of a spindle 121 connected to a rotational drive source such as a motor (not shown), and a grindstone 123 is attached to the tip surface of the grindstone mounting portion 122. Reference numeral 17 denotes a dressing grindstone, 18 denotes a control circuit that controls a drive system that rotationally drives the polishing tool 12, and 19 denotes a control circuit that controls a drive system that drives the table 12.

  The heating means gives a temperature environment of 60 ° C. or higher to the multilayer ceramic capacitor 3. Various heating means can be considered. For example, the substrate 13 on which the multilayer ceramic capacitor 3 is placed may be heated by a heating wire or the like, or the heated silicon liquid may be flowed from the nozzle 16 to the multilayer ceramic capacitor 3 or a thermostatic chamber. May be used. The temperature environment given to the multilayer ceramic capacitor 3 can be controlled by, for example, a temperature sensor installed in the vicinity of the multilayer ceramic capacitor 3. The upper limit temperature may be set to a temperature that can be withstood by the constituent material of the multilayer ceramic capacitor 3 and the constituent parts of the polishing apparatus 1.

  The resistance measuring device 2 is electrically connected to the terminal electrodes 32 and 33 of the multilayer ceramic capacitor 3 via electric wirings d and e, and measures the insulation resistance between the terminal electrodes 32-33. Reference numeral 21 denotes a power source, and 22 denotes a resistance measurement circuit.

  In order to identify a poor insulation layer for the multilayer ceramic capacitor 3 shown in FIG. 1, the multilayer ceramic capacitor 3 is fixedly mounted on the table 11 in the state shown in FIG. Then, as shown in FIG. 3A, the polishing tool 12 is rotationally driven in the direction of arrow c while applying linear feed in the direction of arrow a or b to the table 11, and the multilayer ceramic capacitor 3 is polished. Thus, the multilayer ceramic capacitor 3 can be polished so as to produce a polished surface perpendicular to the stacking direction of the internal electrodes 36 and 37.

  When the multilayer ceramic capacitor 3 is polished, the insulation resistance between the terminal electrodes 32-33 is measured. As shown in FIG. 3B, when the polishing position reaches the defective insulation portion F in the dielectric substrate 1, the measured resistance is measured. The value rises. In order to identify a poor insulation layer by such a method, it is necessary to increase the measured resistance value with a sufficiently significant difference.

  FIG. 4 is data showing measured resistance values with respect to environmental temperature for a multilayer ceramic capacitor with good insulation and poor insulation. As a dielectric material constituting the dielectric substrate of the multilayer ceramic capacitor, a material mainly composed of barium titanate (B characteristic) was used.

  Referring to FIG. 4, even if the insulation resistance between both terminal electrodes of a multilayer ceramic capacitor is measured under a temperature environment of less than 60 ° C., the measurement is performed between a good insulation product and a poor insulation product of the multilayer ceramic capacitor. It can be seen that there is no significant difference in resistance value.

  On the other hand, when the insulation resistance is measured in a temperature environment of 60 ° C. or higher, it can be seen that there is a sufficiently significant difference in the measured resistance value between the good insulation product and the poor insulation product.

  Therefore, when the polishing of the multilayer ceramic capacitor 3 and the measurement of the insulation resistance are performed in a temperature environment of 60 ° C. or higher, a sufficiently significant difference can be caused in the increase in the measured resistance value accompanying the polishing. When the measured resistance value rises with a sufficiently significant difference, it is possible to clearly detect an increase in the measured resistance value, thereby accurately identifying a poor insulation layer.

  The resistance measuring device 2 of the embodiment gives a control signal to the polishing device 1 when detecting an increase in the measured resistance value. Specifically, the resistance measuring apparatus 2 sends a control signal from the resistance measuring circuit 22 to the control circuits 18 and 19 of the polishing apparatus 1 to stop the operation of the polishing apparatus 1.

  The present invention has been described in detail with reference to the preferred embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made by those skilled in the art based on the basic technical idea and teachings. It is self-evident that

It is sectional drawing which shows an example of the multilayer ceramic capacitor used as the application object of the defect detection method which concerns on this invention. It is a figure which shows the structure of the defect detection apparatus used for implementation of the defect detection method of the multilayer ceramic capacitor which concerns on this invention. It is a figure explaining the defect detection method of the multilayer ceramic capacitor which concerns on this invention. It is data which shows the measured resistance value with respect to environmental temperature about the insulation good product of a multilayer ceramic capacitor, and a poor insulation product.

Explanation of symbols

3 Multilayer Ceramic Capacitor 31 Dielectric Substrate 36, 37 Internal Electrode 31, 32 Terminal Electrode

Claims (2)

A method for detecting defects in a multilayer ceramic capacitor,
In the multilayer ceramic capacitor, a plurality of internal electrodes are embedded in layers inside a dielectric substrate, and the internal electrodes are electrically connected to a pair of terminal electrodes provided on the outer surface of the dielectric substrate,
The multilayer ceramic capacitor is placed in a temperature environment of 60 ° C. or higher,
A defect including steps of polishing the multilayer ceramic capacitor so as to produce a polished surface perpendicular to the stacking direction of the internal electrodes, measuring an insulation resistance between the terminal electrodes, and detecting an insulation failure by increasing a measured resistance value Detection method. A failure detection device for a multilayer ceramic capacitor, which includes a polishing device, a heating means, and a resistance measurement device,
In the multilayer ceramic capacitor, a plurality of internal electrodes are embedded in layers inside a dielectric substrate, and the internal electrodes are electrically connected to a pair of terminal electrodes provided on the outer surface of the dielectric substrate,
The polishing apparatus polishes the multilayer ceramic capacitor so as to produce a polishing surface perpendicular to the stacking direction of the internal electrodes,
The heating means gives a temperature environment of 60 ° C. or higher to the multilayer ceramic capacitor,
The resistance measurement device is a defect detection device that measures an insulation resistance between the terminal electrodes of the multilayer ceramic capacitor.

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