Shielded probe with low contact resistance for testing a device under test
View Patent ↗A probe measurement system having low, stable contact resistance for measuring the electrical characteristics of integrated circuits or other microelectronic devices at high frequencies.
1. A probe comprising:
(a) a dielectric substrate supporting an elongate conductor on a first side of said substrate and supporting a conductive member on a second side of said substrate, said conductive member including a contact surface on a side of said conductive member distal of said dielectric substrate for contacting a device under test; and
(b) a contact electrically interconnected to said elongate conductor and protruding from said second side of said substrate for contacting said device under test;
(c) wherein said elongate conductor and said conductive member form a controlled impedance structure; and
(d) wherein said probe has a characteristic that its contact resistance when said contact is engaged with un-patterned aluminum of said device under test is generally less than 30 milliohms during any engagement of an initial 5000 engagements of said contact and said un-patterned aluminum.
2. The probe of claim 1 further comprising a resiliently flexible structure interconnected with said dielectric substrate, and a pre-loading mechanism that pre-loads said flexible structure by imparting a pre-load displacement of said structure when said contact is free from being engaged with said device under test in such a manner that when said probe is displaced with said contact in engagement with said device under test a force exerted on said device under test by said contact is greater than said force would be if said pre-load displacement had not been imparted to said flexible structure.
3. The probe of claim 1 further comprising a conductive path between said first side of said substrate and said second side of said substrate.
4. The probe of claim 1 wherein said controlled impedance structure is a microstrip.
5. The probe of claim 2 wherein said flexible structure is a co-axial cable.
6. The probe of claim 1 herein said substrate has a thickness of less than 40 microns with a dielectric constant of less than 7.
7. The probe of claim 3 wherein said conductive path is in a region within the periphery of said substrate for at least a majority of the thickness of said substrate.
8. The probe of claim 1 wherein said elongate conductor is electrically interconnected to a central conductor of a coaxial cable.
9. The probe of claim 1 wherein said conductive member is electrically connected to a conductor surrounding a central conductor of a coaxial cable.
10. The probe of claim 1 wherein said contact resistance generally varies less than 5 mΩ over said initial 5000 engagements of said contact and said un-patterned aluminum.
11. A probe comprising:
(a) a dielectric substrate supporting an elongate conductor on a first side of said substrate and supporting a conductive member on a second side said substrate, said conductive member including a contact surface on a side of said member distal of said substrate for contacting a device under test; and
(b) a contact electrically interconnected to said elongate conductor and protruding from said second side of said substrate for contact with said device under test;
(c) wherein said elongate conductor and said conductive member form a controlled impedance structure; and
(d) wherein said probe has a characteristic that its contact resistance when said contact is engaged with un-patterned aluminum of said device under test is generally less than 35 milliohms throughout a 5 hour period of engagement of said contact and said un-patterned aluminum.
12. The probe of claim 11 wherein said contact resistance generally varies less than 10 milliohms throughout said 5 hour period of engagement of said contact and said un-patterned aluminum.
13. The probe of claim 11 further comprising a resiliently flexible structure interconnected with said dielectric substrate, and a pre-loading mechanism that pre-loads said flexible structure by imparting a pre-load displacement of said structure when said contact is free from being engaged with said device under test in such a manner that when said probe is displaced with said contact in engagement with said device under test a force exerted on said device under test by said contact is greater than said force would be if said pre-load displacement had not been imparted to said flexible structure.
14. The probe of claim 11 further comprising a conductive path between said first side of said substrate and said second side of said substrate.
15. The probe of claim 11 wherein said controlled impedance structure is a microstrip.
16. The probe of claim 13 wherein said flexible structure is a co-axial cable.
17. The probe of claim 11 herein said substrate has a thickness of less than 40 microns with a dielectric constant of less than 7.
18. The probe of claim 14 wherein said conductive path is in a region within the periphery of said substrate for at least a majority of the thickness of said substrate.
19. The probe of claim 11 wherein said elongate conductor is electrically interconnected to a central conductor of a coaxial cable.
20. The probe of claim 11 wherein said conductive member is electrically connected to a conductor surrounding a central conductor of a coaxial cable.