Si strain gauge, bonded to spring-hard brass body; force measurement application
For precision force measurements, the CiS Research Institute from Erfurt has developed miniaturized silicon strain gauges (Si-DMS) with integrated measuring bridge. The piezoresistive resistors are monolithically integrated in single-crystalline silicon (K-factor = 80) and are available as a double strain element and as a full bridge. The use of semiconductor technologies results in higher long-term stability, precision and measurement reliability compared to ductile metal strain gages.
The temperature coefficient of the bridge is 0.70 % / 10 K. The resistance of the bridge at 30 °C is 5000 Ω.
The Si strain gages, which measure only 1.0 mm x 0.5 mm x 0.015 mm, are joined to the elastic deformation body using innovative joining techniques.
Classical bonding methods are often not usable for demanding applications, such as industrial sensors and medical technology, because the joining materials used for this are sensitive to temperature and humidity and thus affect the stability of the electrical signal.
Assembly technologies such as vitrification, silver sintering or joining based on reactive multilayer systems are leading the way here. The selection of the appropriate process depends on the requirements of the measurement system and the conditions at the measurement location. CiS conducts investigations on the thermal behavior of the material components and the reliability and long-term stability of the Si strain gauge on spring bodies made of stainless steel, Kovar, aluminum and other metals. Technological results and first prototypes of the silicon strain gauges will be presented for the first time in 2016.
Project presentations at:
Hannover Messe, April 25-29, 2016, Hannover, Hall 4 Booth F34.
SENSOR+TEST, May 10-12, 2016, Nuremberg, Hall 5 Booth 5-364
Silicon strain gauge as full bridge on glass solder