Fringe-field non-overlapping-electrodes discoidal feed-through ceramic filter capacitor with high breakdown voltage

• US 20020175782A1
• Filed: 05/25/2001
• Published: 11/28/2002
• Est. Priority Date: 05/25/2001
• Status: Active Grant

• Current Assignee: Presidio Components Incorporated
• Original Assignee: Presidio Components Incorporated
• Inventors: Trinh, Hung, Devoe, Daniel F.
• Granted Patent: US 6,545,854 B2
• Time in Patent Office: Days
• US Class Current: 333/182
• CPC Class Codes: H01G 4/35 Feed-through capacitors or anti-noise capacitors

Abstract

The size and placement of internal metallization areas as do collectively form each of two electrodes is improved in a typically discoidal feed-through ceramic filter capacitor having (i) multiple ceramic layers, (ii) a hole passing a wire that carries electrical signals which are to be filtered, (iii) metal lining the hole so as to make electrical contact with the wire, and (iv) an exterior metal band connected to ground. First internal metallization areas, each in the shape of a relatively smaller small-aperture disk, are centered about the body'"'"'s hole in contact with the metal lining, each area being upon one of the body'"'"'s multiple ceramic layers, the areas collectively serving as a first electrode of the capacitor. Second internal metallization areas, each in the shape of a relatively larger large-apertured disk also centered about the hole and upon one of the ceramic layers, make at their exterior edge surface electrical contact with the metal band, thereby to serve as a second electrode of the capacitor. The respective metallization areas of each electrode are both (i) spaced far apart by previous standards, and, preferably, (ii) are located upon alternating ceramic layers, making that any voltage breakdown path is necessarily both (i) long and with (ii) both radial and longitudinal components. According to this long path, the breakdown voltage is high, typically 3000-4000 volts, making the capacitor suitable for, inter alia, implanted cardiac defibrillators.

Claims

1. A feed-through multi-layer ceramic filter capacitor having

a substantially monolithic body of layered ceramic dielectric material with at least one hole, suitable to accept an electrical conductor, passing through at least some layers of the body,

a first plurality of conductive first electrode plates, encased within the body on an associated plurality of ceramic layers, electrically connectable to an electrical conductor within the hole, and

a second plurality of conductive second electrode plates, encased within the body on an associated plurality of ceramic layers, electrically connectable to ground,

CHARACTERIZED IN THAT

the first plurality of conductive first electrode plates are spatially non-overlapping with the second plurality of conductive second electrode plates along any imaginary axis parallel to an axis of the hole.

2. The feed-through multi-layer ceramic filter capacitor according to claim 1 FURTHER CHARACTERIZED IN THAT

at least some of the ceramic layers associated with the first plurality of conductive first electrode plates are the same ceramic layers as are associated with the second plurality of conductive second electrode plates;

wherein at least some of the conductive first, and the conductive second, electrode plates are upon the same ceramic layers.

3. The feed-through multi-layer ceramic filter capacitor according to claim 1 FURTHER CHARACTERIZED IN THAT

none of the ceramic layers associated with the first plurality of conductive first electrode plates are the same as any ceramic layers associated with the second plurality of conductive second electrode plates;

wherein there is at least one ceramic layer located between each conductive first, and each conductive second, electrode plate.

4. In a feed-through filter capacitor having

a substantially discoidal dielectric body having

a major axis,

at least one hole, aligned parallel to the major axis, suitable to accept an electrical conductor, and

an external rim region;

a first set of electrodes, located spaced-parallel within the body transverse to the body'"'"'s axis, electrically connectable to an electrical conductor within the hole; and

a second set of electrodes, also located spaced-parallel within the body transverse to the body'"'"'s axis, electrically connectable to ground at the body'"'"'s rim;

so as to filter to ground any electrical signal upon any electrical conductor fed through the body'"'"'s hole, an improvement

wherein the first set of electrodes are non-overlapping with the second set of electrodes along any imaginary axis parallel to the axis of the at least one hole, meaning that no imaginary axis parallel to the axis of the at least one hole will pass through both an electrode of the first set and, also, and electrode of the second set.

5. The improvement to a feed-through filter capacitor according to claim 4 wherein the substantially discoidal dielectric body comprises:

multi-layer ceramic, with the first and the second sets of electrodes being metal upon the ceramic layers.

6. The improvement to a feed-through filter capacitor according to claim 5

wherein the first and the second sets of electrodes are upon the same ones of the ceramic layers.

7. The improvement to a feed-through filter capacitor according to claim 5

wherein the first and the second sets of electrodes are upon different ones of the ceramic layers.

8. A feed-through ceramic filter capacitor comprising:

multiple ceramic layers as aggregate a substantially planar body;

at least one hole in the body through which hole is passable an electrical conductor carrying electrical signals to be filtered;

first metal serving to line the body'"'"'s hole for making electrical contact with any electrical conductor within the hole;

a plurality of first internal metallization areas each in the shape of a relatively smaller small-aperture disk centered about the body'"'"'s hole upon one of the body'"'"'s multiple ceramic layers, each apertured disk metallization area making at its internal edge surface electrical contact with the metal lining of the hole so as to serve as a first electrode of a capacitor;

second metal serving as a band over at least part of an exterior edge surface of the body, the second metal band being suitably electrically connected to ground;

a plurality of second internal metallization areas each in the shape of a relatively larger large-apertured disk centered about the body'"'"'s hole upon one of the body'"'"'s multiple ceramic layers, each second metallization area making at its exterior edge surface electrical contact with the second metal band so as to serve as a second electrode of a capacitor;

wherein the plurality of first internal metallization areas as collectively constitute a first electrode, and the plurality of second internal metallization areas as collectively constitute a second electrode, are separated from each other radially from a centerline of the body'"'"'s hole; and

wherein upon electrical connection of the first metal to an electrical conductor passing through the hole, and electrical connection of the second metal to ground, a first fringing electrical field is developed at and between the plurality of first internal metallization areas, and a second fringing electrical field is developed at and between the plurality of second internal metallization areas, and there exists a capacitance, suitable for filtering electromagnetic interference/radio frequency interference existing in electrical signals upon the electrical conductor, between this first and this second fringing electrical field.

9. The ceramic filter capacitor according to claim 8

wherein the plurality of first internal metallization areas are upon a first plurality of the multiple ceramic layers;

wherein the plurality of second internal metallization areas are upon a second plurality of the multiple ceramic layers; and

wherein the first plurality of the multiple ceramic layers is interleaved with the second plurality of the multiple ceramic layers, making that the first and the second metallization areas are never on the same layer, but are always separated, first metallization area to second metallization area, not only by the radial distance of separation, but also by a thickness of a ceramic layer.

10. The ceramic filter capacitor according to claim 8 in the substantial shape of an apertured disk with one substantially central hole.

11. The ceramic filter capacitor according to claim 8 in the substantial shape of a multi-apertured substantially planar body with multiple holes each of which is capable of accepting at least one wire.