EMI filter feedthrough having a single-sided oxide-resistant system ground opposite a system ground to an oxidized surface

A hermetically sealed EMI filtered feedthrough for an active medical device (AMD), the EMI filtered feedthrough comprising;

• a) a titanium ferrule comprising a ferrule opening extending to a ferrule device side spaced from a ferrule body fluid side, wherein at least a portion of the ferrule device side has an exposed layer of titanium oxide;
• b) a gold bond pad supported on the ferrule device side;
• c) an electrically non-conductive insulator comprising an insulator outer surface extending to an insulator device side spaced from an insulator body fluid side, wherein the insulator is hermetically sealed to the ferrule in the ferrule opening by a first gold braze so that when the ferrule is attached to an opening in a housing of an AMD, the ferrule and insulator body fluid sides, and the ferrule and insulator device sides reside outside and inside the AMD, respectively, and wherein at least two insulator via holes extend to the insulator device and body fluid sides;
• d) an insulator internal metallization disposed in the at least two insulator via holes;
• e) first and second terminal pins residing in a respective one of the at least two insulator via holes where a second gold braze hermetically seals the terminal pin to the insulator internal metallization, wherein the first and second terminal pins extend to first and second terminal pin first ends spaced from first and second terminal pin second ends, and wherein at least the first and second terminal pin first ends extend outwardly beyond the insulator device side;
• f) a filter capacitor disposed at or adjacent to the insulator device side, the filter capacitor comprising:
• i) a capacitor dielectric comprising a dielectric outer surface extending to a dielectric first major face spaced from a dielectric second major face;
• ii) at least one active electrode plate and at least one ground electrode plate supported in the capacitor dielectric in an interleaved, partially overlapping capacitive relationship;
• iii) first and second dielectric passageways extending into the capacitor dielectric from the dielectric first major face adjacent to the insulator device side;
• iv) a capacitor internal metallization disposed in the first and second dielectric passageways and being conductively connected to the at least one active electrode plate, wherein the outwardly extending first and second terminal pin first ends reside in the respective first and second dielectric passageways where the terminal pins are conductively connected to the capacitor internal metallization connected to the at least one active electrode plate by a first conductive material;
• and
• v) a capacitor external metallization disposed on a terminated first dielectric outer surface portion and on a spaced-apart terminated second dielectric outer surface portion of the dielectric outer Surface, wherein the terminated first dielectric outer surface portion resides spaced above the first gold braze hermetically sealing the insulator to the ferrule, and the terminated second dielectric outer surface portion extends outwardly beyond the first gold braze, and wherein the at least one ground electrode plate is conductively connected to the capacitor external metallization at the terminated first and second dielectric outer surface portions;
• and
• g) a second conductive material connecting the capacitor external metallization at the terminated first dielectric outer surface portion to at least one of the first gold braze sealing the insulator to the ferrule or the gold bond pad supported on the ferrule device side;
• and
• h) a third conductive material connecting the capacitor external metallization at the terminated second dielectric outer surface portion to the exposed layer of titanium oxide on the ferrule device side, spaced outwardly beyond the first gold braze, wherein the third conductive material does not contact the first gold braze sealing the insulator to the ferrule or the gold bond pad supported on the ferrule device side.

A hermetically sealed BMI filtered feedthrough for an active implantable medical device (AMD), the EMI filtered feedthrough comprising:

• a) a titanium ferrule comprising a ferrule opening extending to a ferrule device side spaced from a ferrule body fluid side, wherein at least a portion of the ferrule device side has an exposed layer of titanium oxide;
• b) a gold bond pad supported on the ferrule device side;
• c) an electrically non-conductive insulator comprising an insulator outer surface extending to an insulator device side spaced from an insulator body fluid side, wherein the insulator disposed in the ferrule opening is hermetically sealed to the ferrule by a first gold braze so that when the ferrule is attached to an opening in a housing of an AMD, the ferrule and insulator body fluid sides, and the ferrule and insulator device sides reside outside and inside the AMD, respectively, and wherein at least one insulator via hole extends to the insulator device and body fluid sides;
• d) an insulator internal metallization disposed in the insulator via hole;
• e) a terminal pin residing in the insulator via hole where a second gold braze hermetically seals the terminal pin to the insulator internal metallization, wherein the terminal pin extends to a terminal pin first end spaced from a terminal pin second end, and wherein at least the terminal pin first end extends outwardly beyond the insulator device side;
• f) a filter capacitor disposed at or adjacent to the insulator device side, the filter capacitor comprising:
• i) a capacitor dielectric comprising a dielectric outer surface extending to a dielectric first major face spaced from a dielectric second major face;
• ii) at least one active electrode plate and at least one ground electrode plate supported in the capacitor dielectric in an interleaved, partially overlapping capacitive relationship;
• iii) a dielectric passageway extending into the capacitor dielectric from the dielectric first major face adjacent to the insulator device side;
• iv) a capacitor internal metallization disposed in the iv) dielectric passageway and being conductively connected to the at least one active electrode plate, wherein the outwardly extending terminal pin first end resides in the dielectric passageway where the terminal pin is conductively connected to the capacitor internal metallization connected to the at least one active electrode plate by a first conductive material;
• and
• v) a capacitor external metallization disposed on at least a first portion and a spaced-apart second portion of the dielectric outer surface to provide terminated first and second dielectric outer surface portions that are separated from each other by intermediate and unterminated third and fourth dielectric outer surface portions, wherein the at least one ground electrode plate extends to the terminated first and second dielectric outer surface portions, and the at least one ground electrode plate either does or does not extend to the unterminated third and fourth dielectric outer surface portions;
• and
• g) a second conductive material connecting the terminated first portion of the capacitor external metallization to at least one of the first gold braze sealing the insulator to the ferrule or the gold bond pad supported on the ferrule device side;
• and
• h) a third conductive material connecting the terminated second portion of the capacitor external metallization to the exposed layer of titanium oxide on the ferrule device side, spaced outwardly beyond the first gold braze, wherein the third conductive material does not contact the first gold braze sealing the insulator to the ferrule or the gold bond pad supported on the ferrule device side.