FPP 510 — Temperature-Controlled Four Point Probe

The FPP 510 combines the four point probe head, microprocessor-controlled measurement electronics and a ceramic-plate temperature control unit in a single portable instrument. The probe arm on a vertical slide is positioned with a screw mechanism onto samples of different thickness and size (thin film, thick plate, polymer, coating, textile); the PTFE probe head with 99.9% platinum pins (pin spacing 1 mm, pin diameter 0.5 mm) on a 4 × 4 cm hard ceramic base minimizes contamination and is easy to clean.

Depending on the selected mode, results are read directly on the LCD as Ω/□ (sheet resistance), Ω·cm (bulk/volume resistivity) or Ω (resistance), each with the simultaneous conductivity value in S/cm. Sample thickness (d) and the geometry-dependent correction factor (k) are entered from the keypad; the instrument displays the value computed according to the correction tables in the literature (Topsøe, 1966). 16-bit sampling resolution and averaging of up to 99 samples give stable results; the 20 nA – 10 mA current range protects sensitive, low-conductivity samples, and automatic ranging finds the highest resolution.

The integrated PID temperature control unit (±0.1 °C precision, digital display) holds the ceramic plate between −5 and +80 °C, so the temperature dependence of conductivity (polymers, ionic conductors, semiconductors) is measured on the same setup. 10 Ω / 1 kΩ / 10 kΩ / 1 MΩ reference resistors are supplied with the instrument; in TEST mode, measurement accuracy is checked instantly against them.