Contact resistance measurement


Alfartec developed a contact resistance measurement system of solar cells, which is adaptable to any structure or material.

The BlueCRTLM is a high precision resistance measurement system, it is the fastest way to assesses contact resistances, sheet resistances and bus bar resistivities. In less than 5 minutes it accurately measures more than 25 test structures!

The BlueCRTLM is therefore ideal for R&D or quality control to evaluate contact layer stacks and grid materials.

Key benefits

  • Performance and reliability, thanks to the high quality components used
  • Ultra fast measurements
  • Adaptable to any structure and materials (metals; transparent conductive materials)
  • User friendly HMI and dedicated software


Technical specifications

Current source: 1; 10; 100 microA
1; 3A
Accuracy ± 0.02 %
Voltage range: 100 mV
1; 6; 40 V
Accuracy± 0.02 %
Multiplexer: 80 channels
Contacting plate: 116 pins
custom layout
Vacuum chuck: 20 x 20 mm to 6”
Heating: 25 – 80 °C
Test structure: TLM
Sur mesure
Setup: Contacting system from top or from the side
Software: Programmable measurement sequences Automatical generation of measurement reports
Computer setup: Onboard or external

2 x USB 
1 x RJ45

Weight: measurement unit: approx. 20 Kg
Contacting unit: approx. 20 Kg
Dimensions (wxL x h): measurement unit: approx. 62 x 61 x 30 cm
Contacting unit: approx. 62 x 50 x 60 cm


Principle of operation

Transmission length method (TLM) and bus bar lines (BBL) are the basic test structures of the BlueCRTLM.

A TLM structure is a contact pattern as shown in figure 1. The resistance between pads is accurately measured by four probes method and computed as a function of the pads distance. The contact resistance and the sheet resistance is then calculated by extracting the intercept at d = 0 and the slope of the plot.

Fig. 1: The TLM test structure and the plot of the measured resistance as a function of the pads distance.
Rc and Rsh stand for contact resistance and the sheet resistance respectively.

Bus bar resistivity is measured with bus bar lines structures as shown in figure 2. The resistance is measured with a four probes method as a function of the length. The line resistivity is then deduced from the slope of the plot.

Fig. 2: The bus bar line test structure and the plot of the measured resistance as a function of length. Rline stand for the line resistivity.


Other test structures like four probe measurements or Cox structure are also available.

© Alfartec Sàrl - 2014/2018 | Rue Numa-Droz 158, 2300 La Chaux-de-Fonds | IDE CHE-351.930.951