Hermetically sealed controlled impedance feedthrough assembly
An assembly for passing controlled impedance electrical signals between two different environments via feedthroughs in a feedthrough block. The feedthrough has a signal coupling, a dielectric surrounding the signal coupling, and a ground coupling surrounding the dielectric. An electrically insulating block has an electrically conductive signal link and discrete electrically conductive ground links surrounding the signal link. An electrically conductive block has a separate dielectric spacer and signal link through the spacer. The junctions between the block, links, and spacer are sealed to hermetically separate the two environments. In one method, the components are press fit, leaving no gap between adjacent components. In another method, potting material is forced into the junctions between components.
1. A controlled impedance feedthrough assembly between a first environment and a second environment, the feedthrough assembly comprising:
(a) an electrically conductive block having a first surface and a second surface;
(b) at least one feedthrough in the block extending between the first surface and the second surface, the feedthrough comprising:
a spacer through aperture extending between the first surface and the second surface;
a dielectric spacer within the spacer through aperture having a first face recessed from the first surface forming a first gap between the first surface and first face, and a second face recessed from the second surface forming a second gap between the second surface and second face;
a signal through aperture extending between the first face and the second face; and
a rigid, electrically-conductive signal link in the signal through aperture having a first end at the first surface and a second end at the second surface;
the feedthrough being hermetically sealed between the first surface and the second surface by filling the first gap and the second gap with an epoxy.
2. The controlled impedance feedthrough assembly of claim 1 wherein the first gap and the second gap are at least 0.01 inch in depth.
3. The controlled impedance feedthrough assembly of claim 1 further comprising a flange separating the first environment and the second environment, the block being mounted within an opening in the flange, the seam between the block and flange being hermetically sealed.
4. The controlled impedance feedthrough assembly of claim 1 wherein the signal link and signal through aperture are shaped to prevent the signal link from being pushed through the signal through aperture and wherein the spacer and spacer aperture are shaped to prevent the spacer from being pushed through the spacer aperture.
5. The controlled impedance feedthrough assembly of claim 4 wherein the first end of the signal link has a head with a larger diameter than a diameter of the signal through aperture.
6. The controlled impedance feedthrough assembly of claim 4 wherein the spacer aperture has a stepped diameter creating a shoulder such that a diameter of the first opening is larger than the diameter of the second opening, and wherein the spacer abuts the shoulder.
7. A controlled impedance feedthrough assembly between a first environment and a second environment, the feedthrough assembly comprising:
(a) an electrically non-conductive block having a first surface and a second surface;
(b) at least one feedthrough in the block extending between the first surface and the second surface, the feedthrough comprising:
a signal through aperture extending between the first surface and the second surface;
a rigid, electrically-conductive signal link in the signal through aperture having a first end at the first surface and a second end at the second surface;
a ground coupling extending between the first surface and the second surface;
the feedthrough being hermetically sealed between the first surface and the second surface by forcing an epoxy between the signal link and the block.
8. The controlled impedance feedthrough assembly of claim 7 wherein the ground coupling includes a plurality of rigid, electrically conductive ground links in ground through apertures extending between the first surface and the second surface, the ground links being arranged in a circle surrounding the signal link, an epoxy forced between each ground link and the block.
9. The controlled impedance feedthrough assembly of claim 7 further comprising a flange separating the first environment and the second environment, the block being mounted within an opening in the flange, the seam between the block and flange being hermetically sealed.
10. The controlled impedance feedthrough assembly of claim 7 wherein the signal link and signal through aperture are shaped to prevent the signal link from being pushed through the signal through aperture and wherein the ground links and ground through apertures are shaped to prevent the ground links from being pushed through the ground through apertures.
11. The controlled impedance feedthrough assembly of claim 10 wherein the first end of the signal link has a head with a larger diameter than a diameter of the signal through aperture and wherein the first end of the ground links has a head with a larger diameter than a diameter of the ground through aperture.