JPH0384472A - Ceramic component evaluation device - Google Patents

Abstract

PURPOSE:To evaluate the connection state of internal electrodes of a ceramic component by applying a voltage from outside while the ceramic component is cut and the internal electrodes are exposed. CONSTITUTION:The laminate ceramic capacitor is cut in parallel to the direction where external electrodes face each other to expose the internal electrodes. Its section is polished specularly by using alumina abrasive grains to form an observation surface. When the voltage is applied to both ends of the external electrodes from outside and the surface is irradiated with an electron beam 9 with a 5kV acceleration voltage, a secondary electron image and a reflected electron image are both observed in white. When the polarity of the voltage is inverted, opposite-side internal electrodes are observed in white. When the voltage is applied from outside at the position where the presence of the internal electrodes is confirmed while the voltage is not applied, electrode breaking is observed where the image is not observed in white to find an electric disconnection.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a ceramic component evaluation device, and more particularly to a ceramic component evaluation device for observing the electrode state of a ceramic component and the potential distribution of the ceramic part.

[Prior Art and its Problems] In recent years, ceramic components such as ceramic capacitors, piezoelectric elements, wiring boards, and ceramic varistors have been used in large quantities in electronic devices.

With the miniaturization of electronic devices, these ceramic components are required to be smaller and equipped with advanced functions. For this reason, these ceramic parts are becoming increasingly laminated with electrodes inserted inside them, and the internal electrodes are also required to be made thinner. For this reason,
When manufacturing ceramic electronic components, problems have arisen in which internal electrodes break midway and are not connected as designed. In addition, thinner layers are required in areas where ceramic materials function, and uniformity of materials is required, but there is a problem that there is no way to evaluate uniformity at the stage of making parts. there were.

Conventionally, the method used to solve the above problem was to observe the cross section of the ceramic part using a metallurgical microscope, scanning electron microscope, etc., and estimate the shape and size of the grains in the ceramic part and internal metal electrodes. .

However, these methods could not confirm whether the internal metal electrodes were actually connected. Another problem was that there was no means for evaluating the uniformity of the material composition and the uniformity of the potential distribution during voltage application.

The present invention has been made in order to solve the conventional problems as described above, and includes problems such as the connection state of internal metal electrodes of ceramic parts, uniformity of composition of ceramic parts, uniformity of potential distribution when voltage is applied, etc. The purpose of the present invention is to provide a ceramic component evaluation device that evaluates ceramic parts.

[Means for Solving the Problems] The present invention provides a voltage application device that externally applies a voltage to a ceramic component, an electron beam source that irradiates the ceramic component with an electron beam, and an electron beam source that irradiates the ceramic component with an electron beam. This is a ceramic component evaluation device characterized by comprising a detector for detecting the amount of secondary electrons or reflected electrons generated by the above-described method.

[Function] When a voltage is applied from the outside with the internal electrodes exposed by cutting the ceramic component, a relatively large number of secondary electrons and reflected electrons are generated in areas where the internal electrodes are negatively charged. Observed white. Therefore, regarding the negative electrode side internal electrode, it can be seen that the electrode is cut in areas where white is not observed despite the presence of the internal electrode. Further, regarding the positive internal electrode, if the electrode is cut, a white area spreads from the negative electrodes on both sides, and this can be determined from the fact that the space between the two negative electrodes is observed to be white. If the polarity of the voltage applied from the outside is roughly reversed, the same thing as above is observed at the opposite electrode.

In the manner described above, the connection state of the internal electrodes of the ceramic component can be evaluated.

On the other hand, the uniformity of the composition and the uniformity of the potential distribution of a ceramic component can be evaluated based on the same principle as described above by observing the density of secondary electron or backscattered electron images.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

Example 1 FIG. 1 is a schematic diagram of an embodiment of the present invention.

In this example, a scanning electron microscope whose electron gun uses a tungsten filament was modified to provide a ceramic component evaluation apparatus. A flange 5 equipped with a connector is attached to the side wall of the sample chamber of the scanning electron microscope @ 1 so that a voltage can be applied from the outside, and a voltage is applied to the sample (ceramic component) 2 inside the sample chamber. A sample holder 3 and a secondary electron or backscattered electron detector 4 are installed. The sample holder 3 is electrically insulated from the scanning electron microscope. A voltage is applied to sample 2 from the outside? The voltage of li6 could be changed continuously up to 1oov, and the polarity could be reversed.

A multilayer ceramic capacitor was evaluated using the ceramic component evaluation apparatus configured as described above.

The multilayer ceramic capacitor was cut parallel to the direction in which the external electrodes faced each other to expose the internal electrode portion. This cross section was mirror-polished using alumina abrasive grains to provide an observation surface. A voltage was applied from the outside to both ends of the external electrode, an electron beam was irradiated with an accelerating voltage of 5 kV, and a secondary electron image and a backscattered electron image were observed.

As a result, areas where the internal electrodes were negatively charged were observed as white in both the secondary electron image and the backscattered electron image. When the polarity of the voltage was reversed, the internal electrode on the opposite side was observed to be white. In areas where the presence of internal electrodes was confirmed when no voltage was applied, areas that did not appear white when external voltage was applied were observed to have broken electrodes and were not electrically connected. . On the other hand, if the positively charged internal electrode is disconnected, a white region spreads from the negative electrodes on both sides, and a white area between the two negative electrodes is observed. This is because, since there is no positive electrode, the potential between the negative electrodes and the ceramic surface becomes equal.

FIG. 2 is a diagram schematically showing a secondary electron image observed in this example, where 7 is a negative internal electrode and 8 is a positive internal electrode. In the figure, the shaded areas are observed as white because a large amount of secondary electrons or reflected electrons are generated.

Furthermore, the principle of this embodiment is shown in FIG. In FIG. 3, the size of the arrow of the secondary electron or reflected electron 10 represents the edge of the secondary electron or reflected electron detected by the detector 4 when the electron beam 9 is irradiated.

This example confirmed that the apparatus according to the present invention is effective as an apparatus for inspecting the connection state of internal electrodes of a multilayer ceramic capacitor.

Example 2 The following evaluation was performed using the same ceramic component evaluation apparatus as in Example 1.

A zinc oxide-based multilayer ceramic varistor was cut parallel to the direction in which the external electrodes faced each other to expose the internal electrode portion. This cross section was mirror-polished using alumina abrasive grains to provide an observation surface. A voltage was applied from the outside to both ends of the external electrode, an electron beam was irradiated with an accelerating voltage of 5 kV, and a secondary electron image was observed. A varistor is a nonlinear element that is a dielectric when the applied voltage is low, but becomes a conductor when the applied voltage is high. In the apparatus according to the present invention, when a current flows through the sample due to an externally applied voltage, the secondary electron image is distorted by the magnetic field induced by the current. Therefore, a secondary electron image was observed using this device by applying an applied voltage of 10 μ so that the current flowing through the varistor was 1 mA or less.

As a result, the density of the secondary electron image was observed in the zinc oxide layer of the varistor, and the potential distribution could be observed. From the non-uniform potential distribution, it can be easily inferred that varistor current flows.

Roughly, when we observed several samples of zinc oxide varistors with different compositions using the device according to the present invention, we found that the composition of the samples with uniform potential distribution and the characteristics when made into products. It was found that there was little variation. As described above, it has been found that the apparatus according to the present invention is also useful for studying material compositions.

[Effects of the Invention] As explained above, the ceramic component evaluation device according to the present invention can be applied to observing the connection form of internal electrodes in ceramic components, especially laminated ceramic components, and optimizing the composition of ceramic materials. Therefore, it can be applied to quality control of ceramic parts and is extremely useful.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention, FIG. 2 is a diagram schematically showing a secondary electron image observed in an embodiment of the present invention, and FIG. 3 is a diagram showing the use of an apparatus according to the present invention. FIG. 2 is an explanatory diagram illustrating the principle by which shading appears in a secondary electron image when a ceramic component is observed. 1... Scanning electron microscope 2... Sample (ceramic parts) 3... Sample holder 4... Secondary electron or backscattered electron detector 5... Flange 6... Power supply 7... Negative electrode Side internal electrode 8...Positive side internal electrode 9...Electron beam 10...Secondary electron or reflected electron agent

Claims (1)

[Claims] (1) A voltage application device that applies voltage from the outside to a ceramic component, an electron beam source that irradiates the ceramic component with an electron beam, and secondary electrons or reflected electrons generated by irradiating the ceramic component with the electron beam. A ceramic component evaluation device comprising: a detector for detecting the amount of .