US Patent 7397255 Micro Kelvin probes and micro Kelvin probe methodology

A micro Kelvin probe assembly and method of accomplishing a micro Kelvin measurement that determines the resistance or impedance of a device under test (DUT) that has two spaced contacts. An ammeter is used to flow current through the DUT, and a voltmeter is used to measure the voltage drop across the DUT. There is a printed circuit board (PCB) carrying two pairs of contacts, with a trace leading to each contact. Anisotropic conductive elastomer (ACE) material as an electrical interposer is placed in electrical contact with each of the PCB contacts. The DUT is placed on the ACE such that each DUT contact is directly opposite one pair of PCB contacts. The ammeter is connected to one trace leading to one contact of each pair of PCB contacts to flow current through the DUT, and the voltmeter is connected to the other trace leading to the other contact of each pair of PCB contacts, so that voltmeter can measure the voltage drop across the DUT without an effect caused by the interposer.