JP3055375B2 - Direction identification method for multilayer ceramic capacitors - Google Patents

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 multilayer ceramic capacitor using 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 state of being stacked on each other via the dielectric ceramic layers, and a predetermined one of the internal electrode layers. And an external electrode connected thereto, and has a rectangular parallelepiped shape. As the internal electrode layer, a noble metal such as Pd, Pt, or Ag, or a base metal such as Ni or Cu for the purpose of reducing the cost of the internal electrode material is used.

In this multilayer ceramic capacitor,
In order to improve the 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 multilayer ceramic capacitor is taped and wrapped in a state of being housed in a cavity, and then mounted on a circuit board by a mounting machine. In order to increase the reliability of the mounting, the height of the chip in the cavity is increased. It is necessary to suppress variations in the dimensions. For this reason, the direction of the internal electrode layer is identified, the chip is accommodated in the cavity in the same direction,
Need to tap. In addition, as a method of detecting internal structural defects such as delamination occurring between the dielectric ceramic layer and the internal electrode layer, an ultrasonic flaw detector is used to irradiate the multilayer ceramic capacitor with ultrasonic waves and analyze the reflected waves. In this case, a method of inspecting the presence or absence of a defect is adopted. In this case, too, it is necessary to apply ultrasonic waves vertically to the internal electrode layer in order to increase the detection sensitivity of delamination, and therefore, it is required to identify the direction of the internal electrode layer before the ultrasonic inspection test. is there.

Heretofore, the direction of the internal electrode layers of this multilayer ceramic capacitor having a rectangular parallelepiped shape, 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 difference in design between the thickness direction in which the internal electrode layers of the multilayer ceramic capacitor are stacked and the width direction of the internal electrode layers, they are identified based on the difference in dimensions. On the other hand, there is little 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 characteristic that is slightly convex, the characteristic is visually observed or discriminated.

[0005]

The conventional method of visually observing the color and the convex shape of the ceramic surface of a prismatic multilayer ceramic capacitor and visually identifying the direction of the internal electrode layer is based on a visual method. However, the discrimination accuracy is poor, which causes the mounting reliability of the taped multilayer ceramic capacitor and the accuracy of the ultrasonic inspection test to deteriorate.

Accordingly, 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 to realize a prismatic multilayer ceramic capacitor having an internal electrode layer made of a ferromagnetic material. Of the internal electrode layer, that is, the direction of the internal electrode layer, is accurately and non-destructively provided.

[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, which are arranged via a dielectric ceramic layer. A constant magnetic field that rotates at least 90 degrees around the multilayer ceramic capacitor is applied to the multilayer ceramic capacitor while keeping the multilayer ceramic capacitor parallel to the lead-out surface of the internal electrode layer, and is applied to the multilayer ceramic capacitor. The direction of the magnetic field is changed to measure the magnetization state of the multilayer ceramic capacitor.

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

[0009]

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

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for identifying the direction of a multilayer ceramic capacitor according to the present invention will be described based on 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 1.1, in which an internal electrode layer is made of ferromagnetic Ni.
25 mm, thickness 1.25 mm square prism-shaped multilayer ceramic capacitor, 2 is multilayer ceramic capacitor 1
The internal electrode layer 3 is the same as the multilayer ceramic capacitor 1
External electrodes. Reference numeral 4 denotes an electromagnet (pole piece) for applying a fixed magnetic field rotating around the multilayer ceramic capacitor 1 while keeping the multilayer ceramic capacitor 1 parallel to the internal electrode layer lead-out surface. Furthermore, H
Is the direction of application of the magnetic field, R is the direction of rotation of the magnetic field,
M is a measurement direction of the magnetization of the multilayer ceramic capacitor 1.

First, the dependence of the magnetization of the multilayer ceramic capacitor 1 on the incident angle of the magnetic field was determined by changing the direction H of the magnetic field applied to the multilayer ceramic capacitor 1. That is, the internal electrode layer 2, which has been confirmed by removing a part of the external electrode 3 in advance, is stacked so that the internal electrode layer 2 is perpendicular to the direction H of the magnetic field and the surface of the external electrode 3 is positioned vertically. The ceramic capacitor 1 was arranged between the electromagnets 4. Then, the strength of the magnetic field is fixed to 10 kOe, and the magnetic field is rotated around the multilayer ceramic capacitor 1 while keeping parallel to the internal electrode layer lead-out surface, so that the angle of incidence of the magnetic field on the internal electrode layer 2 becomes 90 degrees. The angle was changed by 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 multilayer ceramic capacitor changes as the angle of incidence of the magnetic field on its internal electrode layer changes. In other words, when the angle of incidence of the magnetic field on the internal electrode layers is vertical or parallel, the magnetization of the multilayer ceramic capacitor shows a maximum, and when the angle of incidence of the magnetic field on the internal electrode layers is vertical, it is compared with when the angle is parallel. As a result, the magnetization increases.

Therefore, for example, at least 9 degrees more than an angle substantially perpendicular to any surface from which the internal electrode layer is not led out.
Rotate the magnetic field around the multilayer ceramic capacitor and measure the magnetization while maintaining parallel to the internal electrode layer lead-out surface at least 0 degrees, and examine the relative magnitudes and time series of the detected multiple peak values of the magnetization. Thus, the direction of the internal electrode layer of the ceramic capacitor can be identified.

Incidentally, the intensity of the magnetic field applied to the multilayer ceramic capacitor is 1
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 less than that and is unsaturated.

In the above embodiment, the direction of the magnetic field applied to the multilayer ceramic capacitor is changed by rotating the magnetic field. However, the present invention is not limited to this. The ceramic capacitor may be rotated about the facing 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 a substantially rectangular prism, but may be another rectangular parallelepiped.

[0016]

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

Accordingly, the direction in which the tape member is housed in the cavity in the tape member can be kept constant, and the variation in chip height in the cavity can be suppressed, so that the mounting reliability in the mounting machine can be improved.

Further, by diverting the same configuration, it is possible to dispose a chip in an ultrasonic flaw detector so that ultrasonic waves are irradiated perpendicularly to the internal electrode layer, and to accurately inspect internal structural defects such as delamination. it can. In this case, it goes without saying that the ultrasonic irradiator is the electromagnet of the previous embodiment.

[Brief description of the 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 a magnetic field incident angle dependency of magnetization of a multilayer ceramic capacitor.

[Explanation of symbols]

 Reference Signs List 1 multilayer ceramic capacitor 2 internal electrode layer 3 external electrode 4 electromagnet of vibrating sample magnetometer H direction of application of magnetic field R direction of rotation of magnetic field M direction of measurement of magnetization

Claims (2)

(57) [Claims] The present invention relates to a multilayer ceramic capacitor having a plurality of internal electrode layers made of a ferromagnetic material for forming a capacitance and arranged via a dielectric ceramic layer. Applying a constant magnetic field rotating at least 90 degrees or more around the multilayer ceramic capacitor while keeping parallel to the outgoing surface of
A direction identification method for a multilayer ceramic capacitor, comprising: changing a direction of a magnetic field applied to the multilayer ceramic capacitor to measure a magnetization state of the multilayer ceramic capacitor. 2. Changing the direction of a magnetic field applied to the multilayer ceramic capacitor, wherein the magnetic field is fixed, and the multilayer ceramic capacitor is rotated at least 90 degrees or more around the lead-out surface of the opposed internal electrode layer as an axis. 2. The method for identifying the direction of a multilayer ceramic capacitor according to claim 1, wherein: