JPH07115034A - Discrimination method of direction of lamination ceramic capacitor - Google Patents

Abstract

PURPOSE:To provide a method for discriminating the direction of a prismatic layered ceramic capacitor with an inside electrode layer comprised of a ferromagnetic substance accurately by non-destruction. CONSTITUTION:A fixed magnetic field H which rotates along the circumference of a layered ceramic capacitor 1 whose inside electrode layer 2 is a ferromagnetic substance by at least 90 deg. or more while keeping parallel with an inside electrode layer lead-out surface is applied to the layered ceramic capacitor 1 to measure the magnetization state of the layered ceramic capacitor 1. A direction of the inside electrode layer 2 is discriminated by magnetic field incidence degree dependency of the magnetization.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for identifying the direction of a monolithic ceramic capacitor having a ferromagnetic material as an internal electrode.

[0002]

2. Description of the Related Art A multilayer ceramic capacitor includes a plurality of dielectric ceramic layers, a plurality of internal electrode layers arranged in a laminated state with the dielectric ceramic layers interposed therebetween, and predetermined internal electrode layers. It has an external electrode connected to and has a rectangular parallelepiped shape. As the internal electrode layer, a noble metal based metal such as Pd, Pt, Ag or a base metal based metal such as Ni or Cu for the purpose of cost reduction of the internal electrode material is used.

In this laminated ceramic capacitor,
In order to improve its mounting reliability and quality, it may be required to identify the direction, that is, the direction of the internal electrode layer. That is, in general, a laminated ceramic capacitor is mounted on a circuit board by a mounting machine after being taped and packaged in a state of being housed in the cavity. In order to improve the reliability of mounting, the height of a chip in the cavity is increased. It is necessary to suppress variations in size. Therefore, the direction of the internal electrode layer is identified, the chip is housed in the cavity in the same direction,
Need to taping. In addition, as a method of detecting internal structural defects such as delamination that occurs between the dielectric ceramic layer and the internal electrode layer, an ultrasonic flaw tester irradiates the laminated ceramic capacitor with ultrasonic waves and analyzes the reflected waves. A method of inspecting for the presence or absence of a defect by doing so is adopted. Also in this case, in order to increase the detection sensitivity of delamination, it is necessary to apply ultrasonic waves perpendicularly to the internal electrode layer, and therefore it may be required to identify the direction of the internal electrode layer before the ultrasonic flaw detection test. is there.

Conventionally, the direction of the internal electrode layers of this rectangular parallelepiped monolithic ceramic capacitor, in particular, the thickness direction in which the internal electrode layers are stacked and the width direction of the internal electrode layers have been identified as follows. That is, when there is a clear design difference between the thickness direction in which the internal electrode layers of the monolithic ceramic capacitor are stacked and the width direction of the internal electrode layers, they are identified by the size difference. On the other hand, when there is almost no difference in design between the thickness direction in which the internal electrode layers are stacked and the width direction of the internal electrode layers, that is, in the case of a substantially square prism shape, when the internal electrode layers can be seen through the ceramic surface. Has identified the color, or in general, when the surface in the thickness direction in which the internal electrode layers are stacked has a slight convex shape, the characteristic is visually observed and identified.

[0005]

The conventional method of identifying the direction of the internal electrode layers by visually observing the shade or convex shape of the ceramic surface of the prismatic monolithic ceramic capacitor depends on the visual method. Therefore, the identification accuracy is poor, which causes the mounting reliability of the taped laminated ceramic capacitor and the accuracy of the ultrasonic flaw detection test to be deteriorated.

Therefore, an object of the present invention is to pay attention to the fact that an internal electrode layer made of a ferromagnetic material such as Ni is magnetized by an external magnetic field, and a prismatic laminated ceramic capacitor having an internal electrode layer made of a ferromagnetic material. The object of the present invention is to provide a method of accurately identifying the direction of the internal electrode layer, that is, the direction of the internal electrode layer in a nondestructive manner.

[0007]

In order to achieve the above object, the present invention has a plurality of internal electrode layers made of a ferromagnetic material for forming a capacitance arranged through a dielectric ceramic layer. To the monolithic ceramic capacitor, a constant magnetic field that rotates at least 90 degrees around the monolithic ceramic capacitor while maintaining parallel to the lead-out surface of the internal electrode layer is applied to the monolithic ceramic capacitor. The magnetization state of the monolithic ceramic capacitor is measured by changing the direction of the magnetic field.

When changing the direction of the magnetic field applied to the monolithic ceramic capacitor, the magnetic field may be fixed and the monolithic ceramic capacitor may be rotated about the lead-out surface of the facing internal electrode layer.

[0009]

The internal electrode layers of the monolithic ceramic capacitor targeted by the present invention are made of a ferromagnetic material such as Ni. Therefore,
When the direction of the magnetic field applied to the monolithic ceramic capacitor is changed, the magnetic flux passing through the internal electrode layers is changed, and the degree of magnetization of the monolithic ceramic capacitor is changed. Therefore, the direction of the monolithic ceramic capacitor can be identified by the difference in the dependence of the magnetization on the incident angle of the magnetic field on the monolithic ceramic capacitor.

[0010]

The method for identifying the direction of a monolithic ceramic capacitor according to the present invention will be described below with reference to embodiments. FIG. 1 is a perspective view of a magnetization measurement of a multilayer ceramic capacitor using a vibrating sample magnetometer. In the figure, reference numeral 1 denotes a length dimension of 2.0 mm and a width dimension of 1.
25 mm, thickness 1.25 mm prismatic prism-shaped monolithic ceramic capacitor, 2 monolithic ceramic capacitor 1
The internal electrode layers of 3 are the same as the multilayer ceramic capacitor 1
External electrodes. Reference numeral 4 denotes an electromagnet (pole piece) that applies a constant magnetic field to the monolithic ceramic capacitor 1 so as to rotate around the monolithic ceramic capacitor 1 while keeping parallel to the internal electrode layer leading surface. Furthermore, H
Is the magnetic field application direction, R is the magnetic field rotation direction,
M is the measurement direction of the magnetization of the monolithic ceramic capacitor 1.

First, the direction H of the magnetic field applied to the monolithic ceramic capacitor 1 was changed to determine the magnetic field incident angle dependence of the magnetization of the monolithic ceramic capacitor 1. That is, the internal electrode layers 2 which have been confirmed by removing a part of the external electrodes 3 in advance are stacked so that the internal electrode layers 2 are perpendicular to the direction H of the magnetic field and the surfaces of the external electrodes 3 are positioned vertically. The ceramic capacitor 1 was arranged between the electromagnets 4. Then, the strength of the magnetic field is fixed at 10 kOe, and the magnetic field is rotated around the laminated ceramic capacitor 1 while keeping the parallel to the lead-out surface of the internal electrode layer, and the incident angle of the magnetic field to the internal electrode layer 2 is changed from 90 degrees. The magnetization was changed in 360 degrees and the magnetization in the direction M perpendicular to the plane of rotation of the magnetic field at that time was measured. The result is shown in FIG.

As shown in FIG. 2, the magnetization of the monolithic ceramic capacitor changes as the angle of incidence of the magnetic field on its internal electrode layer changes. That is, when the angle of incidence of the magnetic field on the internal electrode layer is vertical or parallel, the magnetization of the monolithic ceramic capacitor exhibits a maximum, and moreover, when the angle of incidence of the magnetic field on the internal electrode layer is vertical, it is compared to when it is parallel. Then the magnetization increases.

Therefore, for example, at least 9 from an angle substantially perpendicular to any one surface where the internal electrode layers are not led out.
The magnetization is measured by rotating the magnetic field around the monolithic ceramic capacitor while maintaining parallel to the internal electrode layer lead-out surface at 0 degrees or more, and the relative magnitudes of a plurality of detected magnetization peak values and their time series are investigated. Thus, the direction of the internal electrode layer of the ceramic capacitor can be identified.

Incidentally, the strength of the magnetic field applied to the monolithic ceramic capacitor is such that the magnetization is saturated in the above embodiment.
Although a magnetic field of 0 kOe is applied, the magnetic field is not limited to this and may be a magnetic field in a region where the magnetization is lower than that is unsaturated.

In the above embodiment, the magnetic field is rotated to change the direction of the magnetic field applied to the monolithic ceramic capacitor. However, the present invention is not limited to this, and the magnetic field is fixed in the opposite direction, and the monolithic ceramic capacitor is laminated. The ceramic capacitor may be rotated around the opposing internal electrode layer lead-out surface as an axis. Further, in the present invention, the laminated ceramic capacitor to be identified is not necessarily limited to the one having a substantially regular prism shape, and may be another rectangular parallelepiped one.

[0016]

As is apparent from the above description, according to the method for identifying the direction of a laminated ceramic capacitor having a ferromagnetic material as an internal electrode layer of the present invention, when the direction of a magnetic field applied to the internal electrode layer is changed, Since the magnetic flux passing through the internal electrode layers changes, the state of magnetization of the internal electrode layers changes. By measuring the dependence of the magnetization on the incident angle of the magnetic field, the direction of the multilayer ceramic capacitor having the ferromagnetic material as the internal electrode layer can be accurately identified in a nondestructive manner.

Therefore, the direction in which the tape member accommodates the chip in the cavity can be made constant, and the variation in the chip height in the cavity can be suppressed to enhance the mounting reliability in the mounting machine.

Further, by using the same structure, the chip is arranged on the ultrasonic flaw detector so that the internal electrode layer is irradiated with ultrasonic waves vertically, and internal structural defects such as delamination can be accurately inspected. it can. In this case, it goes without saying that the ultrasonic wave irradiation device serves as the electromagnet of the previous embodiment.

[Brief description of drawings]

FIG. 1 is a perspective view of a magnetization measurement of a multilayer ceramic capacitor using a vibrating sample magnetometer.

FIG. 2 is a graph showing the magnetic field incident angle dependence of the magnetization of a monolithic ceramic capacitor.

[Explanation of symbols]

 1 Multilayer Ceramic Capacitor 2 Internal Electrode Layer 3 External Electrode 4 Electromagnet of Vibration Sample Magnetometer H Magnetic Field Application Direction R Magnetic Field Rotation Direction M Magnetization Measurement Direction

Claims (2)

[Claims] 1. A monolithic ceramic capacitor having a plurality of internal electrode layers made of a ferromagnetic material for forming a capacitance, which are arranged via dielectric ceramic layers, wherein the monolithic ceramic capacitor has internal electrode layers. A constant magnetic field that rotates at least 90 degrees or more around the monolithic ceramic capacitor while maintaining parallel to the derivation surface of
A method for identifying a direction of a monolithic ceramic capacitor, which comprises changing a direction of a magnetic field applied to the monolithic ceramic capacitor to measure a magnetization state of the monolithic ceramic capacitor. 2. When changing the direction of the magnetic field applied to the monolithic ceramic capacitor, the magnetic field is fixed and the monolithic ceramic capacitor is rotated at least 90 degrees or more around the lead-out surface of the facing internal electrode layer. 2. The method for identifying the direction of a monolithic ceramic capacitor according to claim 1.