Shielded probe for testing a device under test
View Patent ↗A probe for measuring the electrical characteristics of integrated circuits or other microelectronic devices at high frequencies may include a dielectric substrate that supports a signal path interconnecting test instrumentation and a probe tip and a ground path that shields both the signal path and the probe tip.
1. A probe comprising:
(a) a dielectric substrate;
(b) an elongate conductor suitable to be electrically interconnected to a test signal supported by said substrate;
(c) a conductive member suitable to be electrically interconnected to a ground signal supported by said substrate;
(d) a contact electrically interconnected to said elongate conductor for testing a device under test;
(e) wherein said elongate conductor and said conductive member form a controlled impedance structure;
(f) wherein said substrate has a thickness of less than 40 microns with a dielectric constant of less than 7.
2. The probe of claim 1 wherein said controlled impedance structure is a microstrip structure.
3. The probe of claim 1 wherein said elongate conductor is supported on a first side of said substrate and wherein said conductive member is supported on a second side of said substrate.
4. The probe of claim 1 further comprising a conductive path electrically connected to said elongate conductor that extends between a first side of said substrate and a second side of said substrate and said conductive path free from electrical interconnection with said conductive member.
5. The probe of claim 4 wherein said conductive path between said first side and said second side is in a manner free from an air gap between the conductive path and the end of said substrate for at least a majority of the thickness of said substrate.
6. The probe of claim 4 wherein said contact is in the form of a bump.
7. The probe of claim 1 wherein said elongate conductor is electrically interconnected to a central conductor of a coaxial cable.
8. The probe of claim 7 wherein said conductive member is electrically connected to a conductor surrounding said central conductor of said coaxial cable.
9. The probe of claim 8 wherein said substrate is supported by said coaxial cable.
10. The probe of claim 9 wherein said substrate is supported by a shelf of said coaxial cable.
11. The probe of claim 1 wherein said conductive member is substantially planar.
12. The probe of claim 1 wherein said dielectric substrate is semi-flexible.
13. The probe of claim 1 wherein said dielectric substrate has a dielectric constant less than 5.
14. The probe of claim 1 wherein said dielectric substrate has a dielectric constant less than 4.
15. The probe of claim 1 wherein said dielectric substrate has a dielectric constant less than 2.
16. The probe of claim 1 wherein said conductive member covers greater than 50% of a side of said substrate.
17. The probe of claim 1 wherein said conductive member covers greater than 60% of a side of said substrate.
18. The probe of claim 1 wherein said conductive member covers greater than 70% of a side of said substrate.
19. The probe of claim 1 wherein said conductive member covers greater than 80% of a side of said substrate.
20. The probe of claim 1 wherein said conductive member covers greater than 90% of a side of said substrate.
21. The probe of claim 1 wherein said contact comprises a via through said substrate.
22. The probe of claim 1 wherein said conductive member laterally surrounds at least 50% of said contact.
23. The probe of claim 1 wherein said conductive member laterally surrounds at least 75% of said contact.
24. The probe of claim 1 wherein said conductive member laterally surrounds at least 100% of said contact.
25. The probe of claim 1 wherein said contact is in the form of a conductive finger.
26. The probe of claim 1 wherein said substrate has a thickness less than 30 microns.
27. The probe of claim 1 wherein said substrate has a thickness less than 20 microns.
28. A probe comprising:
(a) a dielectric substrate supporting an elongate conductor on said substrate and a conductive member supported on said substrate;
(b) a contact electrically interconnected to said elongate conductor for testing a device under test;
(c) wherein said elongate conductor and said substrate form a controlled impedance structure;
(d) wherein said contact has a height relative to the adjoining surface of said dielectric substrate of less than 150 microns.
29. The probe of claim 28 wherein said contact has a height relative to the adjoining surface of said dielectric substrate of less than 100 microns.
30. The probe of claim 28 wherein said contact has a height relative to the adjoining surface of said dielectric substrate of less than 75 microns.
31. The probe of claim 28 wherein said contact has a height relative to the adjoining surface of said dielectric substrate of less than 55 microns.
32. The probe of claim 28 further comprising a co-axial cable interconnected to said dielectric substrate, wherein said co-axial cable is maintained in a tensioned state when said contact is free from being engaged with said device under test.
33. The probe of claim 28 herein said substrate has a thickness of less than 40 microns with a dielectric constant of less than 7.