Wimbush Science & Technology

Press Contact Assemblies

We have developed a range of press contact assemblies facilitating the rapid and easy mounting of samples for electrical measurement using the Physical Property Measurement System (PPMS) of Quantum Design. With these press contacts, samples can be prepared for measurement in seconds rather than hours.

PC-RES
PC-ACT

The assemblies are designed to work with the PPMS resistivity, ac transport or electrical transport measurement options. For four-point electrical measurement, the contacts are aligned linearly, with a 2 mm pitch (see detailed schematicOpens in a new window). Samples up to 4 mm in thickness can be accommodated, so long as they can rest stably on the puck surface. Resistivity, IV curve and critical current measurement are all supported (dependent on the installed measurement option). Hall effect measurement requires a different contact arrangement, also available.

Pin Arrangements

Utilising our extensive experience of measurement using the PPMS instrument, we are also able to custom-design press contact assemblies to address your particular measurement challenges. Contact us for more information, or view the detailed schematicOpens in a new window for some of our more common alternative layouts.

Example applications

These assemblies have been making our lives easier in our research laboratories in Germany for over ten years, and are now in use in laboratories around the world. Examples of the types of samples able to be successfully measured are shown in the photographs to the side. Both thin film and bulk samples can be accommodated.


Electrical Transport Option

The new electrical transport measurement option utilises standard resistivity option pucks, and as such any of our press contact assemblies designed for use with the resistivity option will also work with the ETO. Important to note, however, is that only measurement channels 1 and 2 are passed through to the ETO, even though channel 3 remains present.

Van der Pauw Press Contact Assemblies

PC-VDP-ACT

PPMS Application Note 1076-304Opens in a new window describes a method of performing van der Pauw resistivity measurements on samples of arbitrary geometry. Such measurements are ideally suited to a rapid, hassle-free press contact setup, and we have developed assemblies to facilitate this. Using these, all the connections described in the Application Note are neatly and correctly implemented, leaving the user free to simply acquire and process the data. By selecting appropriate pin positions, a single assembly can support samples of multiple sizes: as standard, contact points spaced 2×2, 4×4, 6×6, and 8×8 mm are available to choose from. Custom arrangements are also available — simply contact us for details.

Note that reversed polarity measurements are trivially implemented in the measurement sequence as a means of improving accuracy through the elimination of offset voltages. A further improvement can be achieved by compensating for geometrical effects by additionally making reciprocal measurements; however since only three PPMS measurement channels are available, this requires the incorporation of a switch system, for example utilising our van der Pauw patch box to provide access to the PPMS measurement lines to reverse the contacts during measurement. More specific details of the measurement procedure are available hereOpens in a new window.

Van der Pauw Hall effect measurements are also possible in principle. However, the time taken to reverse the polarity of the applied field between measurements can lead to unsatisfactory results. We are presently working on developing the possibility to conduct these measurements in the PPMS rotator, thereby enabling the sample to be rotated quickly through 180° rather than reversing the field.

Technical Details

Probe materialFull-hard beryllium copper, gold-plated over nickel
Probe typeNeedle point (standard)
Pointed, Concave, Serrated (options)
Contact resistance< 100 mΩ
Current rating3 A
Probe travel2.65 mm
Spring force0.9 N at 2 mm travel
Durability100,000 cycles
Functional temperature2 – 400 K

Ordering Information

PC-RESResistivity press contact assembly (also suitable for ETO)$450
PC-ACTAC transport press contact assembly$450
PC-HALL5-point Hall measurement press contact assembly
(for ac transport option only)
$450

PC-VDP-RESVan der Pauw resistivity press contact assembly
(for resistivity option or ETO)
$450
PC-VDP-ACTVan der Pauw resistivity press contact assembly
(for ac transport option)
$450

PC-TIPReplacement probe tip$10

The press contact assemblies must be mounted onto an existing puck of the appropriate PPMS option (resistivity or ac transport). This requires a (fully reversible) modification of the puck to be made, which is quite straightforward. Easy-to-follow instructions are available hereOpens in a new window. Replacement spring-loaded probe tips are available in the event that one becomes fatigued, damaged or contaminated. These are easily user-exchangeable.