JPH055367B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a chip-type ceramic capacitor used for assembling circuits of various electronic devices.

Prior Art There are various types of chip-type ceramic capacitors, such as rectangular parallelepiped, cylindrical, and cylindrical types.Among these, cylindrical ceramic capacitors generally have a structure as shown in Figure 3. ing.

That is, caps 3, 3 whose inner surfaces have been soldered in advance are fitted onto both ends of a cylindrical ceramic body 1 with electrodes 2, 2 formed on its surface and inner surface, and this is heated in a heating furnace. By remelting (reflowing) the solder, electrical contact between the electrodes 2, 2 and the caps 3, 3 is ensured, and at the same time,
The caps 3, 3 are securely fixed to the ceramic body 1, and the outer surfaces of the caps 3, 3 are also plated with solder to improve solderability to printed circuit boards, etc. In such a cylindrical ceramic capacitor, the electrodes 2,
A silver electrode is adopted as the electrode 2, but such silver electrodes 2, 2 may undergo migration in the presence of moisture, and there is a risk that the electrodes 2, 2 may be short-circuited. The exposed portions of the electrodes 2, 2 on the surface of the ceramic body are plated with solder or copper, and as shown in the figure, a coating 4 is formed with a thermosetting exterior resin such as epoxy resin.

Problems to be Solved by the Invention However, in the ceramic capacitor as described above, there is a problem in the step of heating and reflowing the solder plated on the inner surface of the cap 3, and the step of heating and curing the thermosetting outer resin coating 4. , since a heat shock is applied to the ceramic body 1,
There is a risk that the characteristics of the ceramic capacitor will deteriorate. In addition, in addition to the solder reflow process and the heat curing process of the coating 4, various processes are required, such as the plating process for the electrodes 2, 2 to prevent migration as described above, so the entire process is There are also problems that arise when the number increases. These problems occur not only in the case of cylindrical ceramic capacitors but also in the case of cylindrical ceramic capacitors, but especially in the case of cylindrical ceramic capacitors, the following problems occur.

That is, if it is cylindrical, the air inside the cylindrical ceramic body 1 expands during heating and curing of the above-mentioned exterior resin, and breaks through the exterior resin coating 4, which has not yet been sufficiently hardened, to the outside. As a result, fine ventilation holes may be formed in the coating 4, resulting in poor sealing.Therefore, moist air entering from the outside through these ventilation holes may cause migration of the electrodes 2, 2. There is a problem that can easily occur.

Means for Solving the Problems In order to solve the above problems, the ceramic capacitor of the present invention includes a metal cap covering the end of a ceramic body having an electrode on the surface, and a metal cap covering the entire surface of the outer metal cap and the metal cap. It is characterized in that the entire exposed outer surface of the electrode is covered with a common plating film.

Function In the ceramic capacitor with the above configuration, the electrodes and the cap are coated with a common plating film, so the cap and the electrode can be connected reliably with electricity without having to reflow the solder on the inner surface of the metal cap as in conventional caps. In addition, the cap can be firmly fixed to the ceramic body through the electrode fixed to the ceramic body. In addition, there is no need to go through the trouble of applying solder to the electrodes to prevent electrode migration.
Moreover, the above-mentioned common plating film can serve as a substitute for the need to apply solder plating or the like to the outer surface of the metal cap to improve solderability. Therefore,
It is now possible to omit the plating process on the inner and outer surfaces of the metal cap, its reflow process, and the process of plating the electrodes to prevent migration, which greatly improves manufacturing efficiency. The problem of heat shock caused by the reflow process is solved, and the risk of deterioration of characteristics is reduced accordingly.

Furthermore, even in the case of cylindrical ceramic capacitors, the above-mentioned common plating film prevents the air enclosed in the ceramic body from being released to the outside, so when the exterior resin coating is heated and cured, air vents are opened to release air. This prevents the electrode from migrating and shortening from its counterpart electrode due to moist outside air entering through the ventilation hole.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 illustrates a cylindrical ceramic capacitor using a cylindrical ceramic body 1. As shown in FIG. In this ceramic capacitor, the ceramic body 1
Electrodes 2, 2 are formed at both ends of the metal cap 3, which covers these electrodes 2, 2, respectively.
3 are placed on both ends of the ceramic body 1. Further, the entire outer surface exposed from the ceramic body of the electrode 2 and the metal cap 3 described above and the entire outer surface of the metal cap 3 are coated with a common plating film 5, and the surroundings thereof are covered with resin. Covering 4
is applied.

In such ceramic capacitors,
The common plating film 5 ensures reliable contact between the electrode 2 and the metal cap 3, and the cap 3 is also securely connected to the ceramic body 1 through the electrode held on the ceramic body. Retained.
Therefore, when manufacturing the ceramic capacitor shown in FIG. 1, it is not necessary to apply solder plating or the like to the inner surface of the metal cap 3, and the cap 3 is placed over the end of the ceramic body 1, and then the plating film 5 is applied. As in the past, after covering the ceramic body with a cap with solder plating on the inside, the contact between the cap and the electrode can be ensured by reflow, or the cap can be attached to the ceramic body. There is no need to hold it securely. In addition, ceramic body 1
Migration of the electrode 2 formed on the outer surface of the electrode 2 is also prevented by the common plating film 5 described above. As a result, the ceramic capacitor shown in FIG. 1 is subjected to much less heat shock during the manufacturing process than conventional capacitors, and characteristic deterioration is thereby prevented. In addition, common plating film 5
Since the metal caps 3 are formed to cover the entire outer surfaces of the metal caps 3, there is no need to separately apply solder plating to the caps 3 in advance as in the conventional case.

FIG. 2 illustrates a cylindrical ceramic capacitor using a cylindrical ceramic body 1. In FIG. When the cylindrical ceramic body 1 is used, as described above, the outer resin coating 4 is heated and cured.
The air sealed inside the ceramic body 1 expands and may break through the exterior resin coating 4, which has not yet sufficiently hardened, and escape to the outside, through the minute ventilation holes formed at that time. There is a concern that the intruding moist outside air may cause migration to occur in the electrode 2 formed on the inner surface of the ceramic body 1, but this problem is caused by the fact that the electrode 2 and the cap 3 are covered. Since the common plating film 5 reliably prevents the release of the enclosed air, there is no problem at all. Other matters are the same as those described in FIG.

The plating film 5 can be easily formed by electrolytically plating or electroless plating the electrode 2 and the cap 3 with metal such as solder, tin, or copper.

Effects of the Invention As described above, the ceramic capacitor of the present invention has a common cap that covers the entire outer surface of the metal cap and the entire outer surface of the electrode exposed from the metal cap. Since the cap is covered with a plating film, electrical contact between the two and fixation of the cap to the ceramic body are ensured by the plating film. Therefore, not only can the above-mentioned reflow process be omitted from the manufacturing process, but also the plating process to prevent electrode migration, which was indispensable in the past, and the cap to improve solderability with printed circuit boards. Forming plating on the surface can also be omitted,
Manufacturing efficiency is greatly improved, and there is no risk of property deterioration due to heat shock during reflow. Also, in the case of cylindrical ceramic capacitors, the common plating film acts as a sealing film when heating and curing the outer resin coating, and prevents the release of expanded sealed air, so ventilation holes are provided in the coating. Therefore, migration of the electrodes due to the intrusion of moist outside air is also prevented. Furthermore, in the ceramic capacitor of the present invention, the plating film is visible from the outside, so it is possible to judge by looking at the plating film how well the cap is held against the ceramic body and whether the electrical contact between the electrode and the cap is good or bad. There are also advantages.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a ceramic capacitor using a cylindrical ceramic body according to an embodiment of the present invention, FIG. 2 is a sectional view showing a ceramic capacitor using the same cylindrical ceramic body, and FIG.
The figure is a sectional view showing a conventional ceramic capacitor. 1... Ceramic element body, 2... Electrode, 3... Metal cap, 5... Plating film.

Claims (1)

[Claims] 1. A metal cap is placed over the end of a ceramic body having an electrode on its surface, and the entire outer surface of the metal cap and the entire outer surface of the electrode exposed from the metal cap are covered with a common plating film. Ceramic capacitor.