JPH0426772B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to electronic components such as cylindrical ceramic capacitors,
In particular, it relates to improvements in the metal cap.

Technical background In general, electronic components such as cylindrical porcelain capacitors are
Although the porcelain element is formed by sintering, the diameter of the porcelain element is not constant and "variations" occur due to sintering shrinkage or pressure strain during molding. Therefore, in so-called "metal cap fitting type" electronic components, a problem arises in that the metal cap and the porcelain body fit poorly.

BACKGROUND ART Conventionally, as shown in FIGS. 4A and 4B, an appropriate number of protrusions b are provided on the inner peripheral surface of a metal cap a, and the caps are properly fitted by elastic deformation of the protrusions b. Furthermore, as shown in FIGS. 5A and 5B, an appropriate number of protrusions b are provided on the inner peripheral surface of the metal cap a, and an appropriate number of notches are provided in the axial direction. It has been proposed that the cutout portion c is formed with an elastic deformation of the cutout portion c when in the fitted state to ensure proper fitting.

Problems to be Solved by the Invention However, since the metal cap a is formed to have a uniform wall thickness, in the conventional example shown in FIGS. 4A and 4B, the protrusions b... play a reinforcing role. As the strength increases, as shown in Figure 6,
The protrusions b of the metal cap a are fitted by scraping off the electrode layer e of the porcelain element d without being elastically deformed, which may impair the electrical performance or cause direct pressure to be applied to the porcelain element d. In the past, it was necessary to form the electrode layer e of the ceramic body d thick in advance to avoid the possibility of cracks, resulting in high costs.

Furthermore, in the examples of FIGS. 5A and 5B, if the length of the notch c... is increased, a minute gap may be formed between the metal cap and the porcelain body after fitting, which may impair electrical contact. On the other hand, if the length of the notch c... is shortened, the previous conventional example (fourth
The same problem as in Figures A and 4B) occurred.

The present invention solves these conventional problems, and
It is an object of the present invention to provide an electrical component with a metal cap that can be easily fitted without impairing electrical performance.

Means for Solving the Problems In order to achieve the above object, an electronic component according to the present invention has a plurality of protrusions on the inner circumferential surface, and the thickness of the protrusion is greater than the thickness of other parts. It has a thin metal cap.

According to the above structure, since the protruding part of the metal cap is formed thinner than other parts, it can be elastically deformed, and even if the metal cap is fitted into the porcelain body, the electrical performance will be impaired. A metal cap can be fitted onto a porcelain body without any trouble.

EXAMPLES Hereinafter, the present invention will be explained in detail based on illustrated examples.

In FIG. 2, reference numeral 1 denotes a chip-type electronic component such as a cylindrical ceramic capacitor, which includes a cylindrical ceramic body 2 and left and right parts 1 fitted on both ends of the ceramic body 2.
It consists of a pair of metal caps 3,3.

The metal cap 3 is formed into a cylindrical shape with a bottom by pressing a cold rolled steel plate, and
As shown in FIG. 1, a plurality of protrusions 4 are formed on the inner peripheral surface 5. The outer circumferential surface corresponding to the protrusions 4 is formed into a substantially V-groove shape, and the thickness T of the protrusions 4 is smaller than the thickness t of other parts. Ratio T of the wall thickness T of the protrusion 4 and the wall thickness t of other parts T/
It is desirable to set t in the range of 70 to 95%. However, it is free to set T/t to 70% or less.
Further, the protrusion 4 is formed so that the diameter of the inscribed circle in contact with the protrusion 4 is slightly smaller than the outer diameter of the porcelain body 2. If the inscribed circle of the protrusion 4 is large, there is a risk that a minute gap will be formed between the porcelain body 2 and the metal cap 3 when the metal cap 3 is fitted onto the outside, resulting in poor contact, etc. On the other hand, if the inscribed circles of the projections 4 are too small, there is a risk that the metal cap 3 will damage the porcelain body 2, causing cracks and the like. Here, if the ratio T/t of the thickness of the protrusion 4 and the thickness of the other part is set in the above range of 70 to 95%, the diameter D of the inscribed circle of the protrusion 4 is set to the diameter d of the porcelain body 2. It can be set in the range of 84% to 99%.

Incidentally, in the conventional example in which the protrusion has the same thickness as the other parts, D/d had to be set within a narrow range of 92 to 99%. In this example, as mentioned above, D/d
It is thought that the reason why the setting range of is expanded is that the elastic force of the metal cap is increased by making the protrusions 4 thinner. Further, by setting the diameter of the inscribed circle of the protrusions 4 within the above range, the electrical connection between the metal cap 3 and the porcelain body 2 is made good, and the mechanical connection is also strong. Incidentally, the result was that the fitting strength was 1.65Kg/mm ² to 1.245Kg/mm ² (previously it was 0.5Kg/mm ² or more).

In addition, "variations" in the outer diameter of the porcelain body 2 can be dealt with with one type of metal cap 3, which also has the effect of improving productivity.

The amount of protrusion of the projections 4 can be determined as appropriate depending on the difference between the inner diameter of the cylindrical portion of the metal cap and the outer diameter of the porcelain body.

A copper plating layer 6 and a solder layer 7 are formed on both the inner and outer surfaces of the metal cap 3. An electronic component is assembled by fitting this metal cap 3 onto a ceramic body 2 provided with an electrode layer 8. In this case, the boundary between the electrode layer 8 and the metal cap is usually soldered. 9 in FIG. 3 is solder.

In an electronic component equipped with such a metal cap 3, the protrusions 4 of the metal cap 3 are elastically deformed and fitted onto the porcelain body 2, so that the electrode layer 8 is not scraped off during fitting. Moreover, the metal cap 3 does not come off from the porcelain body 2 even during transportation until it is soldered.

Effects of the Invention The electronic component according to the present invention has a metal cap 3
has a plurality of protrusions 4 on the inner circumferential surface 5, and the wall thickness T of the portion corresponding to the protrusion 4 is formed thinner than the wall thickness t of other portions. 4...
It is easily fitted onto the porcelain body 2 by utilizing the elastic deformation of the porcelain body 2, and does not come off after being fitted. moreover,
The electrode layer 8 is not scraped off during fitting, so the electrode layer 8 can be made thinner than before. In particular, since expensive silver paste is generally used for the electrode layer 8, there is an effect that costs can be reduced.

[Brief explanation of drawings]

Fig. 1 is an enlarged side cross-sectional view showing one embodiment of the present invention, Fig. 2 is a front view thereof, Fig. 3 is an enlarged longitudinal sectional view of the same main part, and Fig. 4A is a front view of main parts showing a conventional example. , FIG. 4B is a side view of the same main part, FIG. 5A is a front view of the main part showing another conventional example, FIG. 5B is a side view of the same main part, and FIG. 6 is for explaining the problems of the conventional method. FIG. 3...Metal cap, 4...Protrusion, 5...Inner peripheral surface.

Claims (1)

[Claims] 1. An electronic component characterized by comprising a metal cap having a plurality of protrusions on its inner circumferential surface, the thickness of the protrusions being thinner than the thickness of other parts.