JPH01144612A - Ceramic electronic component with cap - Google Patents

Abstract

PURPOSE:To make a metallic cap terminal engaged with a ceramic element body with the axis of the cap terminal corresponding to that of the ceramic element body, to unify the stress generated in the cap terminal, and to prevent generation of microcrack, by forming three protrusions which are approximately evenly spaced circumferentially, along the internal peripheral surface of the metallic cap terminal which is to be engaged with the ceramic element body. CONSTITUTION:Three protrusions 20, which are approximately evenly spaced circumferentially, are formed along the internal peripheral surface 12b of a cap terminal 12. When the cap terminal 12 is engaged with the end section of a ceramic element body, the external peripheral surface of the ceramic element body is certainly in contact with all the protrusions 20. Therefore, the pressures which are applied from the respective protrusions 20 to the ceramic element body are approximately unified so that stress does not concentrate on a part of the protrusions. As a result, microcracks can be effectively prevented from being generated in the ceramic element body.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an electronic component such as a cylindrical ceramic capacitor having a metal cap terminal fitted at its end.

A typical prior art metal cap terminal used in this type of electronic component is shown in FIG. This cap terminal 1 is formed into a cylindrical shape with a bottom, and in order to obtain sufficient fitting strength, the inner diameter DI is a ceramic body (not shown).
is selected to be slightly smaller than the outer diameter of. Incidentally, the ceramic body is formed by sintering, but the diameter of the ceramic body is not constant and varies due to sintering shrinkage, pressure strain, etc. during this molding. Therefore, when the end portion of the ceramic body is press-fitted into the cap terminal 1, a large pressing force acts on the ceramic body, and an invisible microcrank is generated.

In order to prevent the occurrence of such microcracks, a cap terminal 2 shown in FIGS. 6 and 7 has been proposed. This cap terminal 2 has a plurality of protrusions 4 formed on its inner circumferential surface 3 at intervals in the circumferential direction. The number of protrusions 4 is approximately 8 to 12. Such a protrusion 4
By providing this, when the cap terminal 2 is fitted to the end of the ceramic body, the surface that comes into contact with the outer peripheral surface of the ceramic body extends over the entire circumferential surface in the case of the cap terminal 1 described above. , in this cap terminal 2, the protrusion 4
Therefore, the cap terminal 2 can be softly fitted to the ceramic body.

However, to issue 5 of the first W decision,
Even when such a cap terminal 2 is used, if there are variations in the outer diameter dimensions of the ceramic body, such as diameter and roundness, the axis of the ceramic body may coincide with the axis of the cap terminal 2. Therefore, among the plurality of protrusions 4, some protrusions come into contact with the outer peripheral surface of the ceramic body, and some protrusions do not come into contact with the outer peripheral surface of the ceramic body. Therefore, the plurality of protrusions 4 cannot press the outer circumferential surface of the ceramic element uniformly, and the pressing force concentrates on some of the protrusions, resulting in large stress being generated in the ceramic element at that part. As a result, microcracks occur.

The purpose of the present invention is to solve the above-mentioned technical problems, to prevent as much as possible the occurrence of micro-cracks in the ceramic body caused when fitting cap terminals, and to obtain sufficient fitting strength. The present invention provides a ceramic electronic component with a cap.

The present invention provides a capped ceramic electronic component comprising a ceramic body and a metal cap terminal fitted to an end of the ceramic body. The gap terminal is characterized in that three protrusions are formed on the inner peripheral surface thereof at approximately equal intervals in the circumferential direction.

According to the above configuration, three protrusions are formed on the inner circumferential surface of the cap terminal at approximately equal intervals in the circumferential direction. Therefore, (1) these three protrusions always come into contact with the outer peripheral surface of the ceramic body, so that the ceramic body is fitted in a centered state in which the axis of the ceramic body coincides with the axis of the cap terminal. Therefore, the stress acting on the ceramic body is made uniform, and local stress concentration as in the prior art is prevented. In addition, since it is supported at 03 points, the span between each protrusion is expanded compared to the prior art where there are 8 to 12 protrusions, and the arc portion of the cap terminal can smoothly deform elastically in the chord direction. As a result, the pressing force of the protrusion is absorbed, and the pressing force of the protrusion is reduced by the absorbed amount.

Due to the above-mentioned reasons (1) and (2), the occurrence of microcracks in the ceramic body can be prevented as much as possible.

FIG. 1 is a perspective view of a cylindrical ceramic capacitor 10 according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of FIG.
It is a sectional view seen from ■. In the figure, 11 is a ceramic body, and 12 is a cylindrical cap terminal with a bottom. As shown in FIG. 2, the ceramic body 11 has an inner electrode 13 and an outer electrode 14 formed around a cylindrical dielectric 15.

The inner surface electrode 13 and the outer surface electrode 14 are formed to face each other with a dielectric 15 in between. 16 is ceramic body 1
This is an exterior resin coating formed on the outer periphery of 1. The cap terminals 12 are made of a metal material with good conductivity, and are fitted onto both ends of the ceramic body 11, and are connected to the inner surface electrode 13 or the outer surface electrode 14, respectively.

3 is a longitudinal sectional view of the cap terminal 12, and FIG. 4 is a front view of the cap terminal 12. This cap terminal 1
Three protrusions 20 are formed on the inner circumferential surface 12b of No. 2 at approximately equal intervals along the circumferential direction. That is, the center point G
The angle θ formed by each protrusion 20 is selected to be approximately 120 degrees.

These protrusions 20 all have the same shape. Further, when the wall thickness t of the cylindrical portion 12a of the cap terminal 12 is, for example, O11, the height H1 of the protrusion 20 is 40 μm, and the length H2 in the longitudinal direction is selected to be about 0.4 mm. These protrusions 20 are formed by press stamping, and have a semicircular arc cross section.

In the ceramic capacitor 10 having such a configuration, when fitting the cap terminal 12 to the end of the ceramic body 11, since there are three protrusions 20, all the protrusions 20 must be fitted to the end of the ceramic body 11. The outer peripheral surfaces touch. That is, when the number of protrusions is 4 or more, the ceramic body 11
There are protrusions that come into contact with the outer circumferential surface of the body, and protrusions that do not come into contact with the outer circumferential surface of the ceramic body 11, which may cause the ceramic body 11 to be fitted in an eccentric state. By arranging the protrusions 4 at approximately equal intervals in the circumferential direction, even if there are variations in the outer diameter of the ceramic body 11, the axis of the ceramic body 11 and the axis of the cap terminal 12 can be aligned. They are fitted in such a way that they match. That is, centering is performed when the cap terminal 12 is fitted into the ceramic body 11. Therefore, the pressing force of each protrusion 20 on the ceramic body 11 is made substantially uniform, and concentration of the pressing force on some protrusions is prevented. This prevents microcranks from occurring in the ceramic body 11.

Furthermore, when the cap terminal 12 is fitted, each protrusion 20 receives a pressing force radially outward from the outer peripheral surface of the ceramic body 11. As a result, the cap terminal 12 is connected to the imaginary line p in FIG.
As shown in 1, it attempts to elastically deform into a triangular shape.

That is, the cylindrical portion 12a of the cap terminal 12 tends to elastically deform from an arc to a chord. At this time, in the present invention, each protrusion 20
The span between the protrusions 20 and 20 is large, and the wider the span, the easier it is to elastically deform, and each protrusion 20
The pressing force on the ceramic body 11 is absorbed. Therefore, the pressing force of the protrusion 20 is reduced by the absorbed amount,
The occurrence of cracks in the ceramic body 11 can be reduced.

For reference, when there are four or more protrusions 20, the span between the protrusions 20 is not sufficient, so the degree of deformation is small, and the pressing force of the protrusions 20 cannot be sufficiently absorbed. Therefore, a large pressing force acts on the ceramic body 11, causing microcracks to occur.

By equalizing the stress and smoothly deforming the cap in this way, the cap terminal 12 can be softly fitted to the ceramic body 11, and sufficient fitting strength can be obtained. Although the above-mentioned embodiments have been described with respect to ceramic capacitors, the present invention can be suitably implemented in other electronic components having gap terminals.

As described above, according to the present invention, it is possible to obtain a good electronic component in which the ceramic element body and the cap terminal have sufficient fitting strength, and the ceramic element body is free from micro-cranks. be able to.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a cylindrical ceramic capacitor 10 according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the section line ■-■ in FIG. 1, and FIG. 3 is a longitudinal cross-section of a cap terminal 12. 4 is a front view of the cap terminal 12, FIG. 5 is a perspective view of the conventional cap terminal 1, FIG. 6 is a longitudinal sectional view of another prior art cap terminal 2, and FIG. 7 is a cap terminal 2. FIG. DESCRIPTION OF SYMBOLS 10... Ceramic capacitor, 11... Ceramic element, 12... Cap terminal, ], 2 b...
Inner peripheral surface of cap terminal 12, 20... protrusion.

Claims (1)

[Claims] A capped ceramic electronic component comprising a ceramic body and a metal cap terminal fitted to an end of the ceramic body, wherein the inner circumferential surface of the cap terminal has a groove extending in the circumferential direction. A ceramic electronic component with a cap, characterized in that three protrusions are formed at approximately equal intervals.