Thermal isolation of cryo-cooled components from circuit boards or other structures

1. An apparatus comprising:

a substantially planar, elongate substrate having a recess in a top surface of the substrate;

a first thermal insulator submerged in the recess of the substrate;

a cover comprising sidewalls and a top portion, wherein inside surfaces of the sidewalls and top portion are covered with a second thermal insulator that, together with the first thermal insulator, defines a thermally-insulated volume;

one or more components to be cooled located over the first thermal insulator and within the thermally-insulated volume;

one or more electrical conductors electrically connected to at least one of the one or more components, each electrical conductor extending laterally over the first thermal insulator and under one of the sidewalls of the cover such that a first portion of the electrical conductor is located within the thermally-insulated volume and a second portion of the electrical conductor is located outside the thermally-insulated volume, wherein the one or more electrical conductors are thermally-insulative at cryogenic temperatures;

one or more conductive traces disposed on the top surface of the substrate outside the thermally-insulated volume, the one or more conductive traces electrically connected to the one or more electrical conductors; and

a dielectric material covering at least the second portion of each electrical conductor that is located outside the thermally-insulated volume and a portion of each conductive trace that is located within the recess.

2. The apparatus of claim 1 , wherein the one or more electrical conductors are submerged in the recess of the substrate.

3. The apparatus of claim 1 , wherein the one or more electrical conductors comprise carbon nanotubes.

4. The apparatus of claim 1 , wherein the one or more conductive traces are impedance matched to the one or more electrical conductors.

5. The apparatus of claim 1 , further comprising:

a cold tip configured to cool the one or more components.

6. The apparatus of claim 5 , wherein the cold tip passes through the cover and physically contacts the one or more components.

7. The apparatus of claim 1 , wherein the first and second thermal insulators comprise foam or aerogel insulation.

8. A system comprising:

a cryocooler; and

an apparatus comprising:

a substantially planar, elongate substrate having a recess in a top surface of the substrate;

a first thermal insulator submerged in the recess of the substrate;

a cover comprising sidewalls and a top portion, wherein inside surfaces of the sidewalls and top portion are covered with a second thermal insulator that, together with the first thermal insulator, defines a thermally-insulated volume;

one or more components to be cooled by the cryocooler, the one or more components located over the first thermal insulator and within the thermally-insulated volume;

one or more electrical conductors electrically connected to at least one of the one or more components, each electrical conductor extending laterally over the first thermal insulator and under an outer edge one of the sidewalls of the cover such that a first portion of the electrical conductor is located within the thermally-insulated volume and a second portion of the electrical conductor is located outside the thermally-insulated volume, wherein the one or more electrical conductors are thermally-insulative at cryogenic temperatures;

one or more conductive traces disposed on the top surface of the substrate outside the thermally-insulated volume, the one or more conductive traces electrically connected to the one or more electrical conductors; and

a dielectric material covering at least the second portion of each electrical conductor that is located outside the thermally-insulated volume and a portion of each conductive trace that is located within the recess.

9. The system of claim 8 , wherein the one or more electrical conductors are submerged in the recess of the substrate.

10. The system of claim 8 , wherein:

the one or more electrical conductors comprise carbon nanotubes; and

the first and second thermal insulators comprise foam or aerogel insulation.

11. The system of claim 8 , wherein:

the cryocooler has a distributed architecture comprising a compressor and multiple expanders coupled by fluid supply/return lines; and

at least one of the expanders is positioned on or proximate the substrate.

12. The system of claim 11 , wherein:

the apparatus comprises multiple substrates;

at least one of the expanders is positioned on or proximate each of the substrates; and

the cryocooler further comprises a distribution manifold configured to provide compressed fluid from the compressor to the expanders.

13. The system of claim 8 , wherein the apparatus further comprises one or more additional electrical components that are not cooled by the cryocooler, the one or more additional electrical components carried by the substrate and located outside the thermally-insulated volume.

14. The system of claim 8 , further comprising:

a cold tip configured to be cooled by the cryocooler and to cool the one or more components.

15. A method comprising:

obtaining a substantially planar, elongate substrate having a recess in a top surface of the substrate and a first thermal insulator submerged in the recess of the substrate;

placing one or more components to be cooled over the first thermal insulator; and

placing a cover comprising sidewalls and a top portion over the one or more components, wherein inside surfaces of the sidewalls and top portion are covered with a second thermal insulator that, together with the first thermal insulator, define a thermally-insulated volume in which the one or more components are located;

wherein at least one of the one or more components electrically contacts one or more electrical conductors, each electrical conductor extending laterally over the first thermal insulator and under one of the sidewalls of the cover such that a first portion of the electrical conductor is located within the thermally-insulated volume and a second portion of the electrical conductor is located outside the thermally-insulated volume, wherein the one or more electrical conductors are thermally-insulative at cryogenic temperatures,

wherein one or more conductive traces disposed on the top surface of the substrate outside the thermally-insulated volume are electrically connected to the one or more electrical conductors, and

wherein a dielectric material covers at least the second portion of each electrical conductor that is located outside the thermally-insulated volume and a portion of each conductive trace that is located within the recess.

16. The method of claim 15 , wherein the one or more electrical conductors are submerged in the recess of the substrate and located over the first thermal insulator.

17. The method of claim 15 , further comprising:

thermally coupling a cold tip to the one or more components.

18. The method of claim 15 , further comprising:

placing an expander of a cryocooler on or proximate the substrate, the expander configured to cool the one or more components.

19. The method of claim 18 , wherein the cryocooler has a distributed architecture comprising a compressor and multiple expanders coupled by fluid supply/return lines.

20. The apparatus of claim 1 , wherein the one or more components, the cover, and the first and second portions of each electrical conductor are positioned completely above the first thermal insulator.