Probe contact resistance

Contact resistance data (Preliminary Analysis)

 The test setup used to collect the data:

  • Programmable load (0-30 volts / 0-150 watt)
  • Programmable power supply (0-30 volts / 300 watt)
  • Probe station with modified wafer chuck with 4" gold plated copper surface
  • LP-600MB Micropositioner
  • 74CJ-APT-KS/100 Quasi-Kelvin Coaxial probe holder with 10 micron radius tungsten probe
  • Agilent DVM with 8.5 digit accuracy
  • Associated coax and non-coax cabling


  • The test setup was assembled to connect power supply to load to probe input (front SSMC connector of the 74CJ-APT-KS)
  • The chuck (floating) was connected to back to the power supply
  • The probe was positioned to make contact with the chuck surface with a typical overdrive of 2-3 mils
  • The Agilent DVM was connected between the 74CJ-APT-KS (rear SSMC connector) and the chuck surface
  • The programmable power supply was set to five (5) VDC / constant voltage
  • A computer/controller was used to control the programmable load in 10 mA increments with a 10 second settle time
  • A computer/controller was use to read and record the differential voltage using the Agilent DVM within the settle time
  • The programmable load used during the preliminary measurement was set to 10 mA to 500 mA (.5 amp) (CC mode) in 10 mA step increments. 

The chart is representative of the voltage drop between the probe and copper target while applying a constant voltage and ramping the programmable load.

The test results can be viewed here

 You will note an anomaly at about 400 mA where the probe station was accidentally bumped causing the probe contact to be somewhat damaged. This damage resulted in higher contact resistance as noted.