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

• US 6,545,854 B2
• Filed: 05/25/2001
• Issued: 04/08/2003
• Est. Priority Date: 05/25/2001
• Status: Active Grant

• Current Assignee: Presidio Components Incorporated
• Original Assignee: Presidio Components Incorporated
• Inventors: Devoe, Daniel F., Trinh, Hung
• Primary Examiner(s): Nguyen, Chau N.
• Assistant Examiner(s): THOMAS, ERIC W
• Application Number:
  US09/865,816
• Publication Number:
  US 20020175782A1
• Time in Patent Office: 683 Days
• Field of Search: 361/301--30, 361/302-305, 361/306--30, 361/307, 361/308.1, 361/309, 361/311, 361/312, 361/320, 361/321--32, 361/328-330
• US Class Current: 361/302
• 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 comprising:

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

first electrode plates electrically connected to the one electrical contact in the hole, each of the first electrode plates being disposed on a layer of dielectric material within the body, and

second electrode plates electrically connected to a ground, each of the second electrode plates being disposed on a layer of dielectric material within the body, the second electrode plates forming the capacitor with the first electrode plates without any intervening electrode plates and the second electrode plates spatially non-overlapping with the first 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 wherein each of the first electrode plates is disposed on a different layer of dielectric material and each of the second electrode plates is disposed on a layer of dielectric material common to one of the first electrode plates.

3. The feed-through multi-layer ceramic filter capacitor according to claim 1 wherein each of the first and second electrode plates is disposed on a different layer of dielectric material.

4. In a feed-through filter capacitor

a substantially discoidal dielectric body having

a plurality of stacked layers of dielectric material,

a major axis extending centrally through the discoidal dielectric body,

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

an external rim region;

a first set of electrodes located within the body transverse to the major axis, each of the first electrodes being disposed on a layer of dielectric material and adapted to be electrically connectable to an electrical conductor within the at least one hole; and

a second set of electrodes located within the body transverse to the major axis, each of the second electrodes being disposed on a layer of dielectric material and adapted to be 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, the second set of electrodes forming the capacitor with the first set of electrodes without any intervening electrode plates, and the first set of electrodes non-overlapping with the second set of electrodes along any imaginary axis parallel to the major axis.

5. The feed-through filter capacitor according to claim 4 wherein the first and the second sets of electrodes being metal upon the ceramic layers.

6. The feed-through filter capacitor according to claim 5 wherein each of the first set of electrodes is disposed on a different layer of dielectric material and each of the second set of electrodes is disposed on a layer of dielectric material common to one of the first set of electrodes.

7. The feed-through filter capacitor according to claim 5 wherein each of the first and second electrode plates is disposed on a different layer of dielectric material.

8. A feed-through ceramic filter capacitor comprising:

multiple ceramic layers forming a body;

at least one hole in the body adapted to receive an electrical conductor carrying electrical signals to be filtered;

a first metal lining the at least one hole and adapted to electrically contact an electrical conductor within the hole;

a plurality of first metallization areas in the shape of apertured disks and having respective apertures centered about the at least one hole upon respective ceramic layers, each first metallization area making at an aperture edge surface electrical contact with the metal lining of the hole so as to serve as a first electrode of a capacitor;

a metal band extending over at least part of an exterior edge surface of the body, the metal band adapted to be electrically connected to ground;

a plurality of second metallization areas having respective apertures centered about the at least one hole upon respective 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;

the plurality of first metallization areas collectively constitute a first electrode, and the plurality of second metallization areas collectively constitute a second electrode separated from the first electrode radially from a centerline of the body'"'"'s hole; and

wherein upon the electrical connection of the first metal to an electrical conductor passing through the at least one hole, and electrical connection of the second metal to ground, a first fringing electrical field is developed at and between the plurality of first metallization areas, and a second fringing electrical field is developed at and between the plurality of second metallization areas, and a fringe-effect capacitance is created by the first and second fringing fields suitable for filtering electromagnetic interference/radio frequency interference existing in electrical signals upon the electrical conductor.

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 wherein the body has one substantially central hole.

11. The ceramic filter capacitor according to claim 8 wherein the body has multiple holes each of which is capable of accepting at least one wire.

12. A feed-through filter capacitor comprising:

layers of dielectric material having at least one hole passing therethrough;

first electrodes disposed on layers of the dielectric material and extending in a first direction substantially perpendicular to a centerline of the at least one hole;

second electrodes disposed on layers of the dielectric material and extending in the first direction; and

the layers of dielectric material being sufficiently thin and the first and second electrodes being sufficiently numerous that a capacitor is formed substantially wholly by fringe-effect capacitance between the first and second electrodes.

13. The feed-through filter capacitor of claim 12 wherein the layers of dielectric material are a ceramic dielectric material.

14. The feed-through filter capacitor of claim 13 wherein the layers of dielectric material comprise a body of the feed-through filter capacitor having an external surface and the feed-through filter capacitor further comprises:

a first electrode contact connected to the first electrodes and formed over a portion of the external surface, the first electrode contact adapted to be electrically connectable to an external contact; and

a second electrode contact electrically connected to the second electrodes and disposed in the at least one hole, the second electrode contact adapted to be electrically connectable to an electrical conductor extending through the at least one hole.

15. The feed-through filter capacitor of claim 14 wherein

each of the first electrodes being disposed on a layer of the dielectric material;

and

each of the second electrodes being disposed on the layer of the dielectric material with a respective one of the first electrodes.

16. The feed-through filter capacitor of claim 14 wherein

each of the first electrodes being disposed on a first layer of the dielectric material;

and

each of the second electrodes being disposed on a second layer of dielectric material different from the first layer.

17. A feed-through filter capacitor comprising:

layers of dielectric material forming a body having an external surface and having a hole passing therethrough;

a first electrode contact formed over a portion of the external surface and adapted to be electrically connectable to an external contact;

a second electrode contact disposed in the hole and adapted to be electrically connectable to an electrical conductor extending through the hole;

spatially overlapping first electrodes disposed on layers of the dielectric material and electrically connected to the first electrode contact; and

spatially overlapping second electrodes disposed on layers of the dielectric material and electrically connected to the second electrode contact, wherein all electrodes in the capacitor spatially overlapping the second electrodes are connected to the second electrode contact.

18. The feed-through filter capacitor of claim 17 wherein all electrodes in the capacitor spatially overlapping the first electrodes are connected to the first electrode contact.

19. The feed-through filter capacitor of claim 17 wherein a capacitor is formed substantially wholly by fringe-effect capacitance between the first and second electrodes.

20. The feed-through filter capacitor of claim 17 wherein the dielectric material is a ceramic dielectric material.

21. The feed-through filter capacitor of claim 17 wherein

each of the first electrodes being disposed on a layer of the dielectric material; and

each of the second electrodes being disposed on the layer of the dielectric material with a respective one of the first electrodes.

22. The feed-through filter capacitor of claim 17 wherein

each of the first electrodes being disposed on a first layer of the dielectric material;

and

each of the second electrodes being disposed on a second layer of dielectric material different from the first layer.

23. A feed-through filter capacitor comprising:

layers of dielectric material forming a body having an external surface and having a hole passing therethrough;

a first electrode contact formed over a portion of the external surface and adapted to be electrically connectable to an external contact;

a second electrode contact disposed in the hole and adapted to be electrically connectable to an electrical conductor extending through the hole;

spatially overlapping first electrodes disposed on layers of the dielectric material and electrically connected to the first electrode contact; and

spatially overlapping second electrodes disposed on layers of the dielectric material and electrically connected to the second electrode contact, wherein all electrodes in the capacitor spatially overlapping the first electrodes are connected to the first electrode contact.

24. A feed-through filter capacitor comprising:

layers of dielectric material having at least one hole passing therethrough;

first electrodes disposed on layers of the dielectric material and extending in a first direction substantially perpendicular to a centerline of the hole;

second electrodes disposed on layers of the dielectric material and extending in the first direction, the second electrodes forming a capacitor with only the first electrodes; and

any one of the first and second electrodes being non-overlapping with any of an other of the first and second electrodes in a second direction substantially parallel to a centerline of the hole.

25. A feed-through filter capacitor comprising:

layers of dielectric material having at least two holes passing therethrough;

first electrodes disposed on layers of the dielectric material and extending in a first direction substantially perpendicular to a centerline of the hole;

second electrodes disposed on layers of the dielectric material and extending in the first direction;

third electrodes disposed on layers of the dielectric material and extending in the first direction; and

the layers of dielectric material being sufficiently thin and the first, second and third electrodes being sufficiently numerous that a first capacitor is formed substantially wholly by fringe-effect capacitance between the first and second electrodes, and a second capacitor is formed substantially wholly by fringe-effect capacitance between the first and third electrodes.

26. The feed-through filter capacitor of claim 25 wherein the dielectric material are a ceramic dielectric material.

27. The feed-through filter capacitor of claim 26 wherein the layers of dielectric material comprise a body of the feed-through filter capacitor having an external surface and the feed-through filter capacitor further comprises:

a first electrode contact connected to the first electrodes and formed over a portion of the external surface, the first electrode contact adapted to be electrically connectable to an external contact;

a second electrode contact connected to the second electrodes and disposed in a first hole, the second electrode contact adapted to be electrically connectable to an electrical conductor extending through the first hole; and

a third electrode contact connected to the third electrodes and disposed in a second hole, the third electrode contact adapted to be electrically connectable to an electrical conductor extending through the second hole.

28. The feed-through filter capacitor of claim 27 wherein

each of the first electrodes being disposed on a layer of the dielectric material;

and

each of the second electrodes being disposed on the layer of the dielectric material with a respective first electrode; and

each of the third electrodes being disposed on the layer of the dielectric material with the respective first electrode.

29. The feed-through filter capacitor of claim 27 wherein

each of the first electrodes being disposed on a first layer of the dielectric material;

and

each of the second electrodes being disposed on a second layer of the dielectric material different from the first layer; and

each of the third electrodes being disposed on the second layer of the dielectric material with a respective second electrode.

30. A feed-through filter capacitor comprising:

layers of dielectric material forming a body having an external surface and having a plurality of holes passing therethrough;

a first electrode contact formed over a portion of the external surface and adapted to be electrically connectable to an external contact;

second electrode contacts, each of the second electrode contacts being disposed in a different one of the holes and adapted to be electrically connectable to an electrical conductor extending through the one of the holes;

spatially overlapping first electrodes disposed on layers of the dielectric material and electrically connected to the first electrode contact; and

spatially overlapping sets of second electrodes, each set of

second electrodes being disposed on layers of the dielectric material and electrically connected to a respective one of the second electrode contacts, wherein all electrodes in the capacitor spatially overlapping a set of second electrodes are connected to the respective one of the second electrode contacts.

31. The feed-through filter capacitor of claim 30 and all electrodes in the capacitor spatially overlapping the first electrodes are connected to the first electrode contact.

32. The feed-through filter capacitor of claim 30 wherein capacitors are formed substantially wholly by fringe-effect capacitance between the first electrodes and each set of second electrodes.

33. The feed-through filter capacitor of claim 30 wherein the dielectric material is a ceramic dielectric material.

34. The feed-through filter capacitor of claim 30 wherein

each of the first electrodes being disposed on a layer of the dielectric material; and

each set of second electrodes being disposed on the layer of the dielectric material with a respective one of the first electrodes.

35. The feed-through filter capacitor of claim 30 wherein

each of the first electrodes being disposed on a first layer of the dielectric material;

and

each set of second electrodes being disposed on a second layer of dielectric material different from the first layer.