Discrete cofired feedthrough filter for medical implanted devices
Discrete cofired feedthrough filters are provided for medical implanted device applications. A plurality of discrete vertical feedthrough filter elements are respectively associated with a plurality of signal wires or pins otherwise supported by an insulating feedthrough and a ferrule. The resulting discrete device comprises a single-element device which is cheaper to make, and which reduces cross-talk between adjacent signal wires/pins while otherwise accommodating changes in feedthrough pitch without having to redesign the filter.
1. A feedthrough filter arrangement for use with an AIMD, comprising:
a ferrule;
a feedthrough associated with said ferrule;
a plurality of conductors supported through said feedthrough; and
a corresponding plurality of discrete filters, each of said filters having at least two respective terminals, with one of said terminals associated with a respective one of said conductors, and the other of said terminals associated with said ferrule;
wherein
said at least two respective terminals comprise side and end terminals associated respectively with said filters and said ferrule; and
each of said filters has two sets of interleaved vertical electrodes comprising ground electrodes and signal electrodes wherein said ground electrodes are associated with at least one end terminal of each respective filter so that ground is connected to said ferrule, and wherein said signal electrodes are associated with at least one side terminal of each respective filler so that signals on a respective associated conductor are connected to such associated conductor.
2. A feedthrough filter arrangement as in claim 1 , wherein said conductors comprise respective wire conductors for each of said discrete filters.
3. A feedthrough filter arrangement as in claim 1 , wherein:
said ferrule comprises a metal ferrule; and
said feedthrough comprises an insulating cofired feedthrough which is mounted relative to said metal ferrule.
4. A feedthrough filter arrangement as in claim 1 , wherein:
each of said filters has two sets of interleaved vertical electrodes comprising ground electrodes and signal electrodes;
each of said ground electrodes has respective projecting end portions connecting with respective end terminals of each of said filters; and
each of said signal electrodes has respective projecting side portions connecting with respective side terminals of each of said filters.
5. A feedthrough filter arrangement as in claim 1 , wherein said respective side and end terminals comprise asymmetrical terminals.
6. A feedthrough filter arrangement as in claim 5 , wherein said feedthrough includes a double row of conductors supported therethrough, and wherein said filters are mounted on said feedthrough in a row with end terminals thereof on alternate sides of said feedthrough.
7. A feedthrough filter arrangement as in claim 1 , wherein the side terminals of said filters comprise respective top and bottom side terminals, with each bottom side terminal respectively connected to the associated conductor of its filter, and with each top side terminal connected to an associated AIMD.
8. A feedthrough filter arrangement as in claim 1 , wherein said respective side and end terminals include at least a pair of end terminals for each respective filter, and comprise symmetrical terminals for each respective filter.
9. A feedthrough filter arrangement as in claim 8 , wherein:
said ferrule comprises a titanium ferrule with sets of upper surface gold pads attached to ground of said ferrule; and
said filters are mounted relative to said ferrule such that said end terminals for each respective filter are attached to a set of said gold pads of said ferrule.
10. A feedthrough filter arrangement as in claim 8 , wherein said conductors are supported in a single row in said feedthrough, and respective end terminals of each of said filters are mounted on opposite sides of said feedthrough, with a bottom side terminal of each of said elements situated over respective of said conductors.
11. A feedthrough filter arrangement as in claim 1 , wherein at least some of said filters further include additional ground electrodes for relatively lower dcR filter characteristics.
12. A feedthrough filter arrangement as in claim 1 , wherein at least some of said filters further include additional signal electrodes for relatively lower ESR filter characteristics.
13. A feedthrough filter arrangement as in claim 1 , wherein at least some of said filters further include:
additional ground electrodes for relatively lower dcR filter characteristics; and
additional signal electrodes for relatively lower ESR filter characteristics; and
wherein said electrodes comprise relatively lower resistance metals.
14. A feedthrough filter arrangement as in claim 1 , wherein said filters include relatively low dielectric materials made from NPO dielectric materials.
15. A feedthrough filter arrangement as in claim 1 , wherein said filters further include a plurality of dummy electrode layers providing nucleation areas for plating formation of filter terminals.
16. A feedthrough filter arrangement as in claim 15 , wherein said ground and signal electrodes and said dummy electrode layers include additional shielding members for relatively increasing the dielectric withstanding voltage characteristics of said filters.
17. A feedthrough filter arrangement for use in association with external circuitry, comprising:
a metal ferrule;
an insulating feedthrough associated with said ferrule;
a plurality of wire conductors supported through said feedthrough; and
a corresponding plurality of discrete cofired filter capacitors, each of said filter capacitors having:
respective end terminals;
a top side terminal;
a bottom side terminal;
a body of dielectric material; and
two sets of interleaved vertical electrodes comprising ground electrodes and signal electrodes received in said body of dielectric material, wherein each of said ground electrodes has respective projecting end portions connecting with respective end terminals of each of said filter capacitors, and each of said signal electrodes has respective projecting side portions connecting with respective side terminals of each of said filter capacitors;
wherein respective end terminals of each of said filter capacitors are mounted on opposite sides of said ferrule for a ground connection therewith, and with a bottom side terminal of each of said filter capacitors connected with a respective one of said conductors for a signal connection therewith, so that each of said top side terminals of said filter capacitors are exposed for respective connections with associated external circuitry.
18. A feedthrough filter arrangement as in claim 17 , wherein at least some of said filter capacitors further include:
additional ground electrodes for relatively lower dcR filter capacitor characteristics; and
additional signal electrodes for relatively lower ESR filter capacitor characteristics.
19. A feedthrough filter arrangement as in claim 17 , wherein:
said ferrule comprises a titanium ferrule with sets of upper surface gold pads attached to ground of said ferrule; and
said filter capacitors are mounted relative to said ferrule such that said end terminals for each respective filter are attached to a set of said gold pads of said ferrule.
20. A feedthrough filter arrangement as in claim 17 , wherein at least some of said filter capacitors further include a plurality of dummy electrode layers providing nucleation areas for plating formation of filter capacitor terminals.
21. A feedthrough filter arrangement as in claim 20 , wherein said ground and signal electrodes and said dummy electrode layers include additional shielding members for relatively increasing the dielectric withstanding voltage characteristics of said filter capacitors.
22. Methodology for a feedthrough filter arrangement for use with an active implanted medical device (AIMD), comprising:
providing a metal ferrule;
fitting an insulating feedthrough with said ferrule;
supporting a plurality of conductors through said feedthrough, wherein the plurality of conductors are arranged in a double row; and
connecting respectively a corresponding plurality of discrete cofired filters with said plurality of conductors, so as to reduce cross-talk between signals on adjacent of said conductors, wherein each of said filters comprises at least one end terminal and at least one side terminal, and wherein said fitters are mounted on said feedthrough in a row with end terminals thereof on alternate sides of said feedthrough.
23. Methodology as in claim 22 , wherein the at least one side terminal is associated with a respective one of said conductors, and the at least one end terminal is associated with said ferrule.
24. Methodology as in claim 23 , further including providing said filter terminals as either symmetrical or asymmetrical terminals.
25. Methodology as in claim 23 , wherein:
each of said filters has two sets of interleaved vertical electrodes comprising ground electrodes and signal electrodes, wherein said ground electrodes are associated with the at least one end terminal of each respective filter so that ground is connected to said ferrule, and wherein said signal electrodes are associated with the at least one side terminal of each respective filter so that signals on a respective associated conductor are connected to such associated conductor.
26. Methodology as in claim 25 , wherein the at least one side terminal of said filters comprise respective top and bottom side terminals, with each bottom side terminal respectively connected to the associated conductor of its filter, and with each top side terminal connected to an associated AIMD.
27. Methodology as in claim 25 , wherein each of said ground electrodes has respective projecting end portions connecting with respective end terminals of each of said filter capacitors, and each of said signal electrodes has respective projecting side portions connecting with respective side terminals of each of said filter capacitors.
28. Methodology as in claim 27 , further including selectively providing additional electrodes to said filter capacitors for relatively lower dcR and/or relatively lower ESR filter characteristics.
29. Methodology as in claim 27 , further including selectively providing a plurality of dummy electrode layers to said filter capacitors for providing nucleation areas for plating formation of filter capacitor terminals.
30. Methodology as in claim 29 , further including selectively providing additional shielding members to selected of said ground and signal electrodes and said dummy electrode layers for relatively increasing the dielectric withstanding voltage characteristics of said filter capacitors.
31. Methodology as in claim 27 , wherein said end terminals of said filter capacitors are mounted on said ferrule using surface tension of solder for self-alignment of said capacitors during a solder reflow step, which causes auto-rotation and centering of the capacitor whenever the solder is heated up for reflow.
32. Methodology as in claim 31 , further including attaching a lead to said capacitor after said reflow step, to secure the positioning of said capacitor relative to said ferrule.