Ground electrical path from an MLCC filter capacitor on an AIMD circuit board to the ferrule of a hermetic feedthrough
An EMI/energy dissipating filter for an active implantable medical device (AIMD) is described. The filter comprises a first gold braze hermetically sealing the insulator to a ferrule that is configured to be mounted in an opening in a housing for the AIMD. A lead wire is hermetically sealed in a passageway through the insulator by a second gold braze. A circuit board substrate is disposed adjacent the insulator. A two-terminal chip capacitor disposed adjacent to the circuit board has an active end metallization that is electrically connected to the active electrode plates and a ground end metallization that is electrically connected to the at least one ground electrode plates of the chip capacitor. There is a ground path electrically extending between the ground end metallization of the chip capacitor and the ferrule. The ground path comprises at least a first electrical connection material connected directly to the first gold braze, and at least an internal ground plate disposed within the circuit board substrate with the internal ground plate being electrically connected to both the first electrical connection material and the ground end metallization of the chip capacitor. An active path electrically extends between the active end metallization of the chip capacitor and the lead wire.
1. A ground electrical path for an EMI/energy dissipating filter assembly for an active implantable medical device (AIMD), the ground electrical path comprising:
a) an electrically conductive ferrule comprising a ferrule opening, the ferrule being configured to hermetically seal an opening in a housing of an AIMD, wherein at least one conductive ground pin is electrically and mechanically connected to the ferrule;
b) an insulator residing in the ferrule opening where a gold braze hermetically seals the insulator to the ferrule, wherein an insulator passageway extends through the insulator to an insulator body fluid side end surface spaced from an insulator device side end surface, and wherein, when the ferrule hermetically sealed to the insulator is attached to the opening in the AIMD housing, the insulator body fluid side end surface and the insulator device side end surface reside outside and inside the AIMD housing, respectively;
c) a conductive active lead wire hermetically sealed to the insulator in the insulator passageway;
d) a circuit board disposed on or adjacent to the insulator device side end surface, wherein a circuit board ground plate or a circuit board ground trace disposed on or inside the circuit board is electrically connected to a circuit board first ground via hole and to a circuit board second ground via hole;
e) a discrete two-terminal MLCC chip capacitor disposed on or adjacent to the circuit board, the discrete two-terminal MLCC chip capacitor comprising a chip capacitor dielectric supporting at least one active electrode plate interleaved in a capacitive relationship with at least one ground electrode plate, wherein an active metallization is electrically connected to the at least one active electrode plate, and a ground metallization is electrically connected to the at least one ground electrode plate of the discrete two-terminal MLCC chip capacitor; and
f) a ground electrical path defined by the circuit board ground plate or the circuit board ground trace being electrically connected to:
i) the ground metallization of the discrete two-terminal MLCC chip capacitor electrically connected through the circuit board first ground via hole; and
ii) the ferrule electrically connected through the at least one ground pin electrically connected to the ferrule and extending into the circuit board second ground via hole; and
g) wherein the active lead wire is electrically connected to the active metallization of the discrete two-terminal MLCC chip capacitor, and
h) wherein the discrete two-terminal MLCC chip capacitor is a first discrete two-terminal MLCC chip capacitor electrically connected to the active lead wire and to the at least one ground pin electrically connected to the ferrule.
2. A ground electrical path for an EMI/energy dissipating filter assembly for an active implantable medical device (AIMD), the ground electrical path comprising:
a) an electrically conductive ferrule comprising a ferrule opening, the ferrule being configured to hermetically seal an opening in a housing of an AIMD, wherein at least one conductive ground pin is electrically and mechanically connected to the ferrule;
b) an insulator residing in the ferrule opening where a gold braze hermetically seals the insulator to the ferrule, wherein an insulator passageway extends through the insulator to an insulator body fluid side end surface spaced from an insulator device side end surface, and wherein, when the ferrule hermetically sealed to the insulator is attached to the opening in the AIMD housing, the insulator body fluid side end surface and the insulator device side end surface reside outside and inside the AIMD housing, respectively;
c) a conductive active lead wire hermetically sealed to the insulator in the insulator passageway;
d) a circuit board disposed on or adjacent to the insulator device side end surface, wherein a circuit board ground plate or a circuit board ground trace disposed on or inside the circuit board is electrically connected to a circuit board ground via hole;
e) a discrete two-terminal MLCC chip capacitor disposed on or adjacent to the circuit board, the discrete two-terminal MLCC chip capacitor comprising a chip capacitor dielectric supporting at least one active electrode plate interleaved in a capacitive relationship with at least one ground electrode plate, wherein an active metallization is electrically connected to the at least one active electrode plate, and a ground metallization is electrically connected to the at least one ground electrode plate of the discrete two-terminal MLCC chip capacitor; and
f) a ground electrical path defined by the circuit board ground plate or the circuit board ground trace being electrically connected to:
i) the ground metallization of the discrete two-terminal MLCC chip capacitor electrically connected through the circuit board ground via hole; and
ii) the at least one ground pin electrically connected to the ferrule,
g) wherein the active lead wire is electrically connected to the active metallization of the discrete two-terminal MLCC chip capacitor, and
h) wherein the discrete two-terminal MLCC chip capacitor is a first discrete two-terminal MLCC chip capacitor electrically connected to the active lead wire and to the at least one ground pin electrically connected to the ferrule.