JPH0421326B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to electronic components such as cylindrical ceramic capacitors, and in particular to the shape of their metal caps.

BACKGROUND TECHNOLOGY Electronic components such as cylindrical ceramic capacitors are generally formed by molding and sintering the element body. The diameter is difficult to be uniform and "variations" tend to occur. Therefore, so-called "metal cap fitting type" electronic components have the disadvantage that the fitting between the metal cap and the element having the electrode formed at the end is poor.

Therefore, conventionally, as shown in FIGS. 4A and 4B, an appropriate number of protrusions b are formed on the inner peripheral surface of the metal cap a.
In some cases, an appropriate number of protrusions b are formed on the inner peripheral surface of the metal cap a, as shown in FIGS. At the same time, an appropriate number of slits (c) are formed in the axial direction, and the portions located between the slits (c) are curved outward, so that the elastic deformation of these portions allows for proper fitting.

Problems to be Solved by the Invention However, since the metal cap a has a uniform thickness, in the first conventional example shown in FIGS. 4A and 4B, the protrusion b... becomes rib-shaped and has a reinforcing effect on the contrary, increasing its strength, and as shown in FIG. There is a risk that a crack may occur if direct pressure is applied to the In this case, the protrusion b...
is press-fitted by cutting off the electrode layer e of the element d, so there is a risk that the electrical performance may be impaired. Therefore, even if the electrode layer e of the element d is formed thick in advance in order to prevent these problems, the problem arises that the cost will be high.

In addition, in the second conventional example shown in FIGS. 5A and 5b, although fitting can be easily achieved by increasing the length of the slit c, the gap between the metal cap a and the end face of the element d after fitting is There is a possibility that a minute gap is formed by the slit c, which may deteriorate the electrical performance.Conversely, if the length of the slit c is shortened, the press-fit cannot be absorbed, and as a result, the first conventional example (Fig. 4A) A problem similar to that shown in FIG. 4B) occurred.

The present invention solves these conventional problems, and
An object of the present invention is to provide an electronic component equipped 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, the present invention provides an electronic component in which a metal cap is attached to the end of an element having an electrode formed at its end. The thickness of the bottom portion is thinner than that of the bottom portion.

Effect According to the above configuration, the metal cap is formed such that the wall thickness of the side surface portion is thinner than the wall thickness of the bottom surface portion, so that the corner portions of the metal cap have elastic force, and the metal cap is attached to the element. An electronic component can be obtained in which the cap can be easily press-fitted and the electrical performance is not impaired.

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

FIG. 2 is a sectional view of a main part of a cylindrical capacitor as an example of an electronic component according to the present invention, showing a cylindrical element 1 and a bottomed cylindrical metal cap fitted onto both ends of the element 1. It consists of 2.

Electrode layers 3 (inner and outer electrodes) are formed on both the inner and outer surfaces of the element 1 using a well-known technique.

As shown in FIG. 1, the metal cap 2 is formed by pressing a cold-rolled steel plate, for example, so that the wall thickness T of the side surface portion 5 is thinner than the wall thickness t of the bottom surface portion 6. . In this case, the wall thickness T is preferably set to 70 to 95% of the wall thickness t. The metal cap 2 having such a shape has elastic solubility at the corners 7, and can absorb variations in the diameter of the element 1 when it is fitted onto the element 1, so that the electrode layer 3 is completely or more than necessary. The metal cap 2 is fitted onto the element 1 without being scraped, and an electronic component can be obtained that does not impair electrical performance.
Although not shown, a copper plating layer and a solder layer are formed on both the inner and outer surfaces of the metal cap 2, and the boundary 4 between the metal cap 2 and the electrode layer 3 is fixed with solder. .

FIG. 3 shows another embodiment of the metal cap 2 used in the present invention, in which an appropriate number of protrusions 8 are formed on the inner peripheral surface of the side surface 5, which is thinner than the bottom surface 6.
...was formed. Moreover, the protrusion 8...
The ratio between the dimension (A) between and the tip and the dimension (B) between the protrusion 8 and the bottom surface 6 is A:B=1:1 ~
The protrusions 8 are arranged at positions such that the ratio is 1:1.7. This position was determined experimentally to ensure that the bending moment of the metal cap 2 to the corner 7 falls within an appropriate range, and that no cracks or the like occur in the element 1 when the metal cap 2 is fitted. This has been confirmed. That is, the closer the protrusions 8 are to the bottom 6 side, the greater the bending moment will cause, making it more likely that cracks will occur in the element 1.
If the position is closer to the tip side, the bending moment during fitting becomes smaller and cracks will not occur in the element 1, but the fitting strength will decrease. Therefore A:
By keeping B within the above range, the mechanical bond is also strengthened.

Further, the protrusions 8 are formed such that the diameter D of the inscribed circle in contact with the protrusions 8 is slightly smaller than the outer diameter of the element 1. In other words, if the inscribed circle of the protrusion 8 is large, the metal cap 2
In the externally fitted state of By fitting cap 2, element 1
or damage the electrode 3, causing cracks, etc.
This is because electrical performance may deteriorate. Then, the ratio T/t of the wall thickness T of the side surface portion 5 and the wall thickness t of the bottom surface portion 6 is set to 70 to 95% as in the first embodiment, and A:B is 1:1 as described above. 1-1:
By providing the protrusions 8 located within the range of 1.7, the ratio D/d between the diameter D of the inscribed circle of the protrusions 8 and the diameter d of the element 1 is set in the range of 84 to 99%. (In the conventional example, the setting of D/d was in a narrow range of 92 to 99%.) In this embodiment, the inner diameter of the side surface 5 of the metal cap 2 is 1.25 mm, the diameter D of the inscribed circle of the projections 8 is 1.15 mm, and the diameter d of the element 1 is 1.25 mm.
1.15 to 1.37 mm, and furthermore, no cracks occur and the metal cap 2 does not come off from the element 1 during transportation. Incidentally, the fitting strength was measured to be 1.70Kg/mm ² to 2.50Kg/mm ² (previously 0.5Kg/mm ² ).

Effects of the Invention As detailed above, in the electronic component of the present invention, since the metal cap is formed so that the wall thickness of the side surface portion is thinner than the wall thickness of the bottom surface portion, the corner portion has elastic force. The metal cap can be easily fitted onto the element and has a high fitting strength. In addition, since the bottom part has a certain thickness that is thicker than the side part, for example, even when lead wires are welded to the outer surface of the bottom part, welding defects such as holes in the metal cap will not occur. . Furthermore, the electrode layer will not be removed completely or more than necessary during fitting.
The electrode layer is thinner than before. Generally, expensive silver paste is used for the electrode layer, and making the electrode layer thinner has the remarkable effect of reducing costs.

[Brief explanation of drawings]

FIG. 1 is an enlarged front sectional view of main parts showing one embodiment of the metal cap used in the electronic component of the present invention, and FIG.
The figure is a front sectional view showing an example of the electronic component of the present invention.
FIG. 3 is a front sectional view showing another embodiment of the metal cap, FIG. 4A is a front view of the main part showing the first conventional example of the metal cap, FIG. 4B is a side view of the main part, and FIG.
Fig. A is a front view of the main part showing a second conventional example of a metal cap, Fig. 5B is a side view of the main part, and Fig. 6 is an enlarged front sectional view of the main part for explaining the problems of the conventional metal cap. DESCRIPTION OF SYMBOLS 1...Element, 2...Metal cap, 5...Side part, 6
...Bottom part, T, t...Thickness.

Claims (1)

[Scope of Claims] 1. An electronic component in which a metal cap is fitted to the end of an element having an electrode formed at its end, wherein the metal cap has a wall thickness at a side surface that is greater than a wall thickness at a bottom surface. An electronic component characterized by being formed to be thin. 2 The wall thickness of the side wall above is 70 to 95% of the wall thickness of the bottom wall.
An electronic component according to claim 1 set forth in claim 1.