JPH0758507A - Laminated filter - Google Patents

Abstract

PURPOSE:To prevent exfoliation by covering an outer circumferential part of an external electrode and an outer circumferential face of a filter main body with a protection film so as to enhance the adhesive strength of an external electrode. CONSTITUTION:An inner electrode 1 used to form the filter is provided between dielectric bodies 3, 4 and between dielectric bodies 4, 5 among the dielectric bodies 2-6 made of a bismuth niobate, and a shield electrode 8 is provided between the dielectric bodies 2, 3 and between the dielectric bodies 5, 6. A protection film 10 covering almost the entire circumference of the film main body 1 is made of a silicon polymer. Then an outer circumferential part of a silver electrode 9a of a lowermost layer of an external electrode 9 is covered by a protection film 10, and a nickel plating electrode and a solder plating electrode 9b are laminated on an inner silver electrode 9a not covered by the protection film 10 to form the external electrode 9. Thus, exfoliation of the silver electrode 9a caused by invasion of plating liquid through a gap between the outer circumferential part of the silver electrode 9a and the filter main body 1 is not occurred.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated filter used for communication equipment and the like.

[0002]

2. Description of the Related Art A conventional laminated filter of this type includes a filter body formed by laminating a plurality of dielectrics, and an internal electrode provided on at least one of the laminated dielectrics of the filter body. The structure is such that it is electrically connected to the internal electrode and has an external electrode provided on the outer peripheral surface of the filter body.

[0003]

The problem with the above structure is that the external electrodes are separated from the filter body. That is, since the external electrode is simply attached to the outer peripheral surface of the filter body, it is easily peeled off. Then, this invention aims at preventing peeling of the external electrode from the filter body.

[0004]

In order to achieve this object, the present invention is one in which the outer peripheral portion of the external electrode and the outer peripheral surface of the filter body are covered with a protective film.

[0005]

With the above structure, since the outer peripheral portion of the external electrode is covered with the protective film provided to enhance the moisture resistance of the outer peripheral surface of the filter body, the adhesion strength of the external electrode is increased and peeling is prevented, Moreover, since a protective film is used for that purpose, it is advantageous in terms of cost.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 denotes a filter body, which is formed by laminating five dielectrics 2 to 6 made of bismuth niobate shown in FIG. An internal electrode 7 for forming a filter is provided between these dielectrics 3 and 4, 4 and 5. Further, a shield electrode 8 is provided between the dielectrics 2 and 3, 5 and 6.
Is provided. Shield electrode 8 and some internal electrodes 7
1 extends to the outer peripheral surface of the filter body 1 on the front side in FIGS. 1 and 2, and is electrically connected to the external electrode 9 here. The internal electrode 7 is made of silver, and the external electrode 9 has a three-layer structure of a lower silver electrode 9a, an intermediate nickel plated electrode, and an upper solder plated electrode. Reference numeral 10 in FIG. 1 denotes a protective film which covers substantially the entire circumference of the filter body and is made of a polymer of silicon. The outer peripheral portion of the lowermost silver electrode 9a of the external electrode 9 is covered with a protective film 10 as shown in FIG. 1, and the above-mentioned nickel-plated electrode is formed on the inner silver electrode 9a portion not covered with the protective film 10. The external electrodes 9 are formed by stacking the solder-plated electrodes 9b. In the formation of the external electrode 9, since the outer peripheral portion of the lower silver electrode 9a is covered with the protective film 10, in the plating process for laminating the nickel plating electrode and the solder plating electrode 9b thereon, the plating solution is Silver electrode 9
There is no possibility that the silver electrode 9a will be peeled off by entering from the gap between the outer peripheral portion of a and the filter body 1. Therefore, the external electrode 9 having the nickel-plated electrode and the solder-plated electrode 9b laminated on the upper side thereof does not peel off. Note that the protective film 10 on the filter body 1 is baked after coating, and the silver electrode 9a of the external electrode 9 is also baked, and the internal electrode 7 and the shield electrode 8 are made of dielectrics 2 to 6.
It has been fired with.

[0007]

As described above, according to the present invention, the outer peripheral portion of the external electrode and the outer peripheral surface of the filter body are covered with the protective film. With the above constitution, the moisture resistance of the outer peripheral surface of the filter body is improved. Since the outer peripheral portion of the external electrode is covered with the protective film provided to enhance the adhesive strength of the external electrode, peeling is prevented and the protective film is used for that purpose, which is advantageous in terms of cost. Will be things.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is an exploded perspective view thereof.

[Explanation of symbols]

 1 Filter body 7 Internal electrode 9 External electrode 10 Protective film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichi Kato 55-12, Ozumi, Osamu, Tanabe-cho, Tsuzuki-gun, Kyoto Prefecture Matsushita Nitto Electric Co., Ltd.

Claims (2)

[Claims] 1. A filter body formed by laminating a plurality of dielectrics, an internal electrode provided on at least one of the laminated dielectrics of the filter body, and electrically connected to the internal electrode. And a external electrode provided on the outer peripheral surface of the filter body, wherein the outer peripheral portion of the external electrode and the outer peripheral surface of the filter body are covered with a protective film. 2. The laminated filter according to claim 1, wherein the protective film is made of a polymer of silicon.