Touch probe with greatly reduced probing force for determining the instrumented indentation hardness
Mar 29, 2023
For the hardness measurement of extremely thin coatings, the classical Vickers or Rockwell methods are not applicable. They require a minimum thickness of more than 100 nm. In comparison, the diameter of the human hair averages 50,000 nm. Pyramid-shaped diamond tips with known geometry are used for hardness measurement of thin films. Since the measurement of the hardness indentation is still only possible with an SEM or AFM, the applied indentation force and the indentation distance of the tip are measured simultaneously during the experiment.
For hardness measurement using the instrumented indentation test method, a displacement-resolved force measurement is required. This requires both a precise force sensor and a precise displacement sensor, as well as a precise diamond tip.
The system developed at the CiS Research Institute meets certain conditions:
• It contains two independently operating force and displacement sensors, one of which is used predominantly for force, and one for displacement measurement.
• The Abbe comparator principle is maintained.
• There is freedom of choice between a diamond tip, carbide ball or robust ball.
• Conformity to the relevant industry standards is maintained.
The nanoindenter assembly has two identical force sensors joined on a rewiring substrate. The displacement sensor is connected to the substrate 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. The position is determined by the distance element, 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 bonds. The PCB is used to attach the sensor to an actuator by means of a bracket.
The research and development work described was funded by the German Federal Ministry of Economic Affairs and Climate Action (BMWK) as part of the research project "Probe system with greatly reduced probing force for determining instrumented indentation hardness" (TARZAN).
Funding code: 49MF160180