Dielectric filter with protective film covering the edges of the

Details Dielectric filter with protective film covering the edges of the Dielectric filter with protective film covering the edges of the

1997-08-22

1999-01-26

Ham, Seungsook

Wave transmission lines and networks

Coupling networks

Wave filters including long line elements

333206, H01P 1205, H01P 1100

Patent

active

058642633

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The present invention relates to a dielectric filter used in communications equipment and a method of manufacturing the dielectric filter. Also, the present invention relates to a protection film for covering the edges of the filter's electrodes
Conventionally, dielectric filters have an island-like input/output electrode, isolated from an external electrode, disposed on the outer side face of dielectrics having multiple through holes from the top to bottom.
One problem faced with a conventional dielectric filter is the peeling of the outer edge of the input/output electrodes and the inner edge of the external electrode of the dielectric filter, which may occur due to external stress, such as heat and twist applied to printed wiring boards when the dielectric filters are mounted to the printed wiring boards.


BRIEF SUMMARY OF THE INVENTION

The object of the present invention is to prevent the peeling of the edges of electrodes of a dielectric filter.
In order to achieve this object, the present invention relates to a dielectric filter comprising, dielectrics having a through hole extending from its top to bottom face, or non-through hole, an external electrode disposed on the outer face of the dielectrics except for the top face, an internal electrode disposed inside the through hole or non-through hole and island-like input/output electrodes, which are disposed on the outer side face of the dielectrics and surrounded by a non-electrode portion of the external electrode. An electrode protection film covers the outer edge of the input/output electrode, the non-electrode portion of the external electrode around the input/output electrode, and the inner edge of the external electrode contacting the non-electrode portion.
With the above structure, the present invention prevents the peeling of the outer edge of the input/output electrode and the inner edge of the outer electrode, which may occur due to external stress, such as when heat is applied thereto. The protective film covers the outer edge of the input/output electrodes and the inner edge of the outer electrode of the dielectric filter.
The invention itself, together with further objects and attendant advantages, will best be understood by reference to the following detailed description taken in conjunction with the accompanying figures.


BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a perspective of a dielectric filter of a preferred embodiment of the present invention.
FIG. 2 is a sectional view of an input/output electrode of the dielectric filter of FIG. 1 depicting a state of application of an electrode protection film.
FIG. 3 is a plan view of an input/output electrode of the dielectric filter of FIG. 1.
FIG. 4 is an exploded perspective view depicting the mounting of a preferred embodiment of a dielectric filter on a printed wiring board.
FIG. 5 is a front section view of the dielectric filter of FIG. 4 of the present invention mounted to a printed wiring board.


DETAILED DESCRIPTION OF THE INVENTION

A preferred embodiment of a dielectric filter of the present invention is described below with reference to the drawings.
FIG. 1 is rectangular dielectrics, or dielectric material, 1 made of BaTiO.sub.3 -system ceramic. The dielectric material 1 has three cylindrical through holes, or non-through holes 2 extending from a top face (the open end) to a bottom face (the short-circuit end), an Ag-system external electrode 3a encasing the dielectrics on the outer side faces and bottom face of the dielectric material, an Ag-system internal electrode 3b on the internal face of each of the through holes 2, and capacity forming electrodes 4. Each capacity forming electrode 4 is connected to an internal electrode 3b, on the top face or open end.
A pair of C-shaped non-electrode portions 5 are disposed in a portion of external electrode 3a formed on an outer side face, at the open end, of the dielectric material 1. An island-like input/output electrode 6 is formed inside each of the C-shaped non-electrode port

REFERENCES:
patent: 5122768 (1992-06-01), Ito et al.
patent: 5288351 (1994-02-01), Hoang et al.
patent: 5365208 (1994-11-01), Ito et al.
patent: 5374910 (1994-12-01), Yamagata
patent: 5495215 (1996-02-01), Newell et al.
patent: 5499004 (1996-03-01), Noguchi et al.
patent: 5517162 (1996-05-01), Ariyoshi

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