JPS59115515A - Cylindrical condenser - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cylindrical capacitor suitable for use in various filters such as π-type filters.

Conventionally, various circuits that combine inductance and capacitance have been used as low-pass filters for high-frequency noise removal, so-called FiM filters.
Among them, the circuit shown in Figure 1 is called a π-type filter,
Widely used.

FIG. 2 is a longitudinal cross-sectional view of a conventional π-type filter.

This filter 1 includes a capacitor C. This capacitor C includes a cylindrical dielectric body 2, two internal electrodes 3a, -3-'b drawn out to opposing end faces 2a, 2b of the dielectric body 20, and both end faces. 2a121) K end face electrodes 5a, 5b electrically connected to these internal electrodes 3a, 3b and these internal electrodes 3a,
3b and a central electrode 4 forming a capacitor. The filter 1 is manufactured as follows.

That is, as shown in FIG. 3, after winding the green belt 5 on which the internal electrodes 3a13b are printed,
It is fired at 400°C, and then, for example, Ag is applied to the entire center of the outer peripheral surface and both end faces.

After applying and drying a conductive paint mainly composed of Ag-Pd or the like, baking is performed at, for example, 800 to 950°C. After press-fitting the outer terminal 6 into the capacitor C made in this way, the stopper 8 as ferrite bead 9 and the capacitor C1 stopper 8b are inserted in order into the K conductor 7.
These parts are fixed by caulking the through conductor 7. It is then immersed in molten solder solution. In this way, the J1 filter 1 is created.

By the way, the conventional cylindrical capacitor C applied to the π-type filter 1 as described above has the following drawbacks. That is, (A) only one dielectric layer can be used to form the center electrode 4, and a large capacity cannot be obtained. (B) Furthermore, since the central electrode is applied using a brush, spatula, spray, etc., the dimensional accuracy is poor and the volume varies widely. 77. In order to increase the capacitance, the width of the center electrode 4 must also be increased. Therefore, the gap width (1
) becomes smaller. Therefore, there is a high possibility that problems such as leakage and migration due to the conductive paint protruding into the gap portion will occur. (C)-! In addition, when assembling the filter or attaching it to the electronic component mounting plate, the external electrodes diffuse into the solder, causing so-called Ag (Ag), which tends to cause poor appearance and capacity drop. Ta.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and provide a cylindrical capacitor with laminated electrodes, small size, large capacity, and high insertion loss. For this purpose, the present invention has a structure in which electrodes that mutually form a capacitor are wound in layers and embedded inside a dielectric, and the outer edge of one electrode is extended to the end face of the dielectric with reeds. The other electrode is drawn out through a groove cut radially inward from the circumferential surface of the dielectric.

Hereinafter, the present invention will be explained in detail based on the embodiments shown in FIGS. 4 to 7.

FIG. 4 is a longitudinal sectional view of a cylindrical capacitor according to the present invention. This cylindrical capacitor 11 includes a dielectric 12 made of ceramic. Inside this dielectric 12, left and right electric fields 13a+13b and a central electrode 14 opposing them and forming a capacitor are wound and embedded. The left and right electrodes 13a and 13b face each other with a predetermined interval maintained only at their inner edges, and each edge is connected to the dielectric material 120.
By extending to both end surfaces 15a, 151)K, it is drawn out to the outside of the dielectric 12. Left and right electrodes 13a and 13 are provided at both ends a and 15b of the dielectric 120, respectively.
1) and an end face electrode 16a electrically connected to the end face electrode 16a.

16b is applied. Further, the dielectric 12 has an innermost center electrode 14 extending radially inward from the center of the outer peripheral surface of the dielectric 12.
A kerf 17 with a depth of By filling the kerf 17 with the conductive member 1B, each central electrode 14 is drawn out to the outer peripheral surface of the dielectric 12. On the outer periphery of the dielectric 12] 11, a narrow annular outer periphery electrode 20 that is electrically connected to the conductive portion 18 is formed. Therefore, the distance between this outer circumferential electrode 20 and the end iu7 electrodes 16a, 161) is
l-1: Quite far apart.

The cylindrical capacitor 11 configured as described above is manufactured as follows. That is, first, a strip-shaped green sheet 21 that will become the dielectric 12 is prepared.

As shown in FIG. 5, on the surface of this green sheet 21, four central electrodes 14 and three pairs of left and right electrodes 13al and 13b are arranged alternately in the direction from the winding start end 21a to the winding end end 211). establish. A predetermined interval is left in the left-right direction between the inner edges of the left and right electrodes 13a and 13b, and the outer edge of the left electrode 13a is connected to the left edge 21C of the green sheet 21.
In addition, the right edge of the right electrode 13b is made to coincide with the right edge 21d of the green sheet 21, respectively. Furthermore, these electrodes 13
A winding end cover portion 218 on which these electrodes 13a, 13b, and 14 are not formed is provided closer to the winding end end 21b than a, 13b, and 14. These electrodes 13al 13b,
14, length z in the winding direction.

12I/i, the green sheet 21 is wound to a length that can be wound approximately once in the finished state. Also, the length I of the end cover part 21e! 3 is a length that allows the green 7-toe 21 to be wound more than once in the finished state.

The left and right electrodes 13a, 13b and the center electrode 14 are made of Ag-Pd' which has excellent high temperature stability! ! It is formed by applying a conductive paint made of PT-PA or the like by a method such as silk printing and drying it. After winding the green/-) 21 in the direction of the arrow with the winding start portion 211L inside, cut grooves 17 are cut radially inward in the center of the circumferential surface until reaching the center electrode 14 of the innermost layer, for example. ], 200~1400°
After baking with C, there is a center electrode 14 and left and right electrodes 13a inside.
A dielectric 12 in which 13b is embedded is obtained. After that, this kerf 17 is filled with a conductive member 18, and a conductive paint is applied to both end surfaces 13a and 131) of the dielectric 12 and the center of the outer peripheral surface covering the conductive member 18, and after drying, for example,
The end electrodes 16a, 16 are baked at 0 to 950'C.
b and the outer peripheral electrode 20 is formed. Thereby, a cylindrical capacitor 11 is obtained. In this example, the grooves 17 were formed before firing, but of course they can be formed after firing.

The cylindrical capacitor 11 thus produced is incorporated into a π-type filter in the same manner as the capacitor 1 shown in FIG.

FIG. 6 is an exploded perspective view of another green sheet used to manufacture the cylindrical capacitor 11.

In this example, two green sheets 31a and 31b are prepared, and one green sheet 31a has left and right electrodes 13a.
, 13b and the center electrode 14 are formed on the other green sheet 311), respectively.

The lengths of these electrodes 13a, 13b, and 14 may be the same or different;
1&, 311) in a state where these electrodes 1
The length must be such that 3a and 13b can be wound in multiple layers and laminated in a layered manner. The inner edges of the left and right electrodes 13a and 13b are arranged at a predetermined interval in the left-right direction, and the left electrode 13
The outer edge of a is Green Sea 1-31. The left edge of a is 310.
The outer edge of the right electrode 13b corresponds to the right edge 31 (i) of the green sheet 31a.The left and right edges of the center electrode 14 correspond to the left and right edges 31e of the green sheet 31b.
, 31f. On the winding end side of each green sheet 31a, 311) from each electrode 13a, 13b+14, there is a winding end portion 31 where no electrode is formed.
g is provided over a length of one or more turns in the winding end state. Then, the other Green Note 31b is layered on top of one Green Note 31a and wound, and fired. Other manufacturing methods are similar to those shown in the previous embodiment. The cylindrical capacitor made in this way is
It has essentially the same effect as that of the above embodiment.

FIG. 7 shows the results of applying the cylindrical capacitor 11 to a filter and comparing its filter characteristics with those of a conventional filter. As is clear from the figure, the filter to which this embodiment is applied exhibits better filter characteristics than the conventional product.

As described above, according to the present invention, a cylindrical dielectric is provided,
Inside this dielectric, electrodes forming a capacitor are alternately wound and buried in layers, and one electrode has its inner edges facing each other at a predetermined interval, and its outer edges are connected to the dielectric. A kerf is formed in this dielectric body from its outer peripheral surface to a depth that reaches the other electrode in the radial direction. By filling the capacitor with a conductive member that conducts with the capacitor, the other electrode is brought out to the outside, so even though it is made to the same dimensions as conventional products, the electrodes that make up the capacitor are formed in multiple layers inside.

Therefore, the cylindrical capacitor can have a large capacity. Furthermore, since the electrodes can be pattern-printed, their dimensions and shapes can be set accurately, and variations in capacitance are almost eliminated. Therefore, variations in properties between products are reduced and acid quality is improved.

Furthermore, since the outer peripheral electrode is not used to obtain capacitance, it can be made much narrower than the central electrode, which has conventionally been formed outside. For this reason, the gap width between the outer peripheral electrode and the end face electrodes formed at both ends of the dielectric becomes large, and porosity and migration/contamination hardly occur. Furthermore, since the electrodes that form the capacitor are all embedded in the dielectric material, it has an excellent practical effect in that even if it is immersed in solder liquid during filter assembly, Ag<<< is not generated and the capacitance does not change. is demonstrated.

[Brief explanation of the drawing]

Figure 1 is an equivalent circuit of a π-type filter, Figure 2 is a vertical cross-sectional view of a π-type filter using a conventional cylindrical capacitor, and Figure 3 is a green sheet used when manufacturing a conventional cylindrical capacitor. FIGS. 4 to 6 show examples of the present invention, FIG. 4 is a vertical cross-sectional view of a cylindrical filter, and FIG. FIG. 6 is an exploded perspective view of a green sort according to an embodiment of the present invention (one length perspective view of another green sort to which the present invention is applied), and FIG. Yes. 11... capacitor, 12... a electric body, 1a a,
13b, 14... Electrode, 15a, 15b... End surface, 17
...kerf, 1B...conductive member. Patent applicant: Tsukita Seisakusho Co., Ltd. Attorney: Kazuhide Okada

Claims (1)

[Claims] (1) A cylindrical dielectric body is provided, and inside this dielectric body, electrodes forming a capacitor are wound around each other and embedded in a layer, and one electrode has its inner edge kept at a Par constant interval. They face each other, and their outer edges extend to the end face of the dielectric and are drawn out, and the dielectric has a groove deep enough to reach the other electrode from the outer circumferential surface inward in the radial direction. A cylindrical capacitor formed by forming a cylindrical capacitor and filling a kerf with a conductive member that conducts with the other electrode to draw out the other electrode to the outside.