The classic Vickers or Rockwell methods are not suitable for hardness measurement of extremely thin layers below 100 nm. Pyramid-shaped diamond tips with known geometry are used for this purpose. The hardness impression is measured with an SEM or AFM. During the experiment, the applied indentation force and the tip indentation distance are measured simultaneously.
For hardness measurement using the instrumented indentation test method, a displacement-resolved force measurement is required. This requires a precise force sensor, a precise displacement sensor and a precise diamond tip.
The system developed at the CiS Research Institute meets the conditions:
• It contains two independently operating force and displacement sensors
• The Abbe comparator principle is maintained
• freedom of choice between a diamond tip, carbide or robust ball
• conforms to relevant industry standards.
The nanoindenter assembly has two identical force sensors joined on a wiring carrier. The force sensor serving as a displacement sensor is connected to the carrier using a flip-chip joining technique. The sensor used as a force sensor, is joined in the same direction to the opposite side with an adhesive. The indenter, for example diamond, is bonded into the intender. A spacer element defines the position, diamond tips and the outer boundary of the element lie in one plane.
The wiring carrier is then joined to the printed circuit board (PCB) by a flip-chip process. The force sensor is electrically connected to the PCB via wire bonding, which attaches the sensor to an actuator using a bracket.
The research and development work described was funded by the German Federal Ministry of Economics and Climate Protection (BMWK) in the research project "Probe system with greatly reduced probing force for determining instrumented indentation hardness" (TARZAN). (FKZ 49MF160180)
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