Co-fired electrical feedthroughs for implantable medical devices having a shielded RF conductive path and impedance matching

• US 8,725,263 B2
• Filed: 07/31/2009
• Issued: 05/13/2014
• Est. Priority Date: 07/31/2009
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Yamamoto, Joyce K., Haubrich, Gregory John
• Primary Examiner(s): GETZOW, SCOTT M
• Application Number:
  US12/533,994
• Publication Number:
  US 20110029036A1
• Time in Patent Office: 1,747 Days
• Field of Search: 607/36, 607/37
• US Class Current: 607/37
• CPC Class Codes: A61N 1/37223 Circuits for electromagnetic coupling
• CPC Class Codes: A61N 1/3754 Feedthroughs

Abstract

A co-fired electrical feedthrough for an implantable medical device (IMD) is provided having a shielded radio frequency (RF) conductive path. The feedthrough includes a monolithic structure derived from one or more layers of dielectric material and a conductive pathway extending through the monolithic structure for communicating RF signals into and from the IMD. An internal shield is formed to extend through at least one of the layers of dielectric material so as to surround the conductive pathway (e.g., in a coaxial relationship) and shield the RF conductive pathway from undesirable signals. This shielding of the RF conductive pathway prevents destructive EMI signals from entering into the IMD through the RF conductive pathway. In some embodiments, a monolithic structure containing embedded impedance matching elements is electrically connected to at least one conductive pathway in the feedthrough to perform impedance matching and/or filtering of the conductive pathway to other circuitry.

Claims

1. An electrical interconnect feedthrough for an implantable medical device (“

IMD”

), comprising;

a monolithic feedthrough structure derived from a plurality of layers of dielectric material;

a conductive pathway extending through the monolithic feedthrough structure for communicating RF signals and comprising at least one via-receiving aperture formed within each of the plurality of layers of dielectric material, wherein each via-receiving aperture couples major planar sides of the respective layer in which the aperture is formed and are laterally offset from each other so that the conductive pathway comprises a substantially serpentine shape extending through the monolithic feedthrough structure;

an conductive metallic material disposed within and at least partially filling each of the via-receiving apertures; and

an interconnect of conductive material formed between two adjacent layers of dielectric material for connecting via-receiving apertures formed in adjacent layers of dielectric material; and

an internal shield formed to extend through the plurality of layers of dielectric material so as to surround the conductive pathway for communicating RF signals, wherein the internal shield comprises a plurality of vias of conductive metallic material formed in each of the plurality of layers of dielectric material so as to surround the conductive pathway formed in the same respective layer of dielectric material, wherein each plurality of vias of conductive metallic material formed in each layer of dielectric material couples major planar sides of the respective layer in which the vias are formed and are laterally offset from each other so that the internal shield comprises a substantially serpentine shape extending through the monolithic feedthrough structure; and

an interconnect of conductive material formed between each adjacent layers of dielectric material for connecting vias of conductive metallic material formed in adjacent layers of dielectric material.

2. The electrical interconnect feedthrough of claim 1, wherein the conductive pathway and the internal shield are formed of a conductive metallic material.

3. The electrical interconnect feedthrough of claim 1, wherein the internal shield is grounded.

4. The electrical interconnect feedthrough of claim 1, wherein the at least one layer of dielectric material comprise a high temperature co-fire ceramic (HTCC) material having a sintering temperature between about 110°

C.° and

1700 C.°

,

further wherein the at least one layer of dielectric material, the conductive pathway and the internal shield are co-fired together at an elevated temperature to form a single monolithic structure.

5. The electrical interconnect feedthrough of claim 1, further comprising:

a signal connection point connected to the conductive pathway on an outer surface of the monolithic feedthrough structure; and

a plurality of shield connection points connected to the internal shield on an outer surface of the monolithic feedthrough structure, wherein the plurality of shield connection points are situated at various locations surrounding the signal connection point,

wherein the signal connection point and the plurality of shield connection points allow the electrical interconnect feedthrough to be attached to another component.

6. The electrical interconnect feedthrough of claim 5, wherein the plurality of shield connection points are spaced apart from each other so as to prevent unwanted or undesirable signals of certain wavelengths from passing there between to reach the signal connection point.

7. The electrical interconnect feedthrough of claim 5, further comprising a monolithic structure containing embedded impedance matching elements electrically connected to the conductive pathway through the signal connection point.

8. The electrical interconnect feedthrough of claim 1, wherein the conductive pathway, internal shield and dielectric layers of the monolithic feedthrough structure comprise geometric shapes and dimensions selected to provide a desired characteristic impedance.

9. The electrical interconnect feedthrough for an implantable medical device (“

IMD”

) of claim 1, further comprising a conductive pathway extending through the monolithic feedthrough structure for providing sensing, therapy, or both.