Probe card with calibrated probe head capacitive distance monitor

Abstract

In probe heads making a large number of contacts to a device under test using flexible probes, the actual overtravel can differ from the programmed overtravel because of the total contact force from all the probes. Thus it is often important to measure the actual overtravel instead of relying on the programmed overtravel and the actual overtravel being the same. Here we provide improved sensing of actual overtravel using capacitive distance sensors that are calibrated to account for the effect of the device under test on capacitive distance measurements.

Images