Patterning and trimming of thin film strain sensors
International Conference of the European Society for Precision Engineering and Nanotechnology (euspen)
27.-31. Mai
Berlin
2013
Type: Konferenzbeitrag
Abstract
Thin film strain sensors are capable of sensing mechanical loads in hostile environments and exhibit large longevity. Laser patterning is a promising approach to overcome existing restriction to 2-D surfaces due to existing manufacturing technologies. In order to fulfil the demand for a cost-efficient manufacturing process, a high throughput is required. At the same time, a high accuracy is required to realize a good signal/noise ratio by interconnection to a Wheatstone bridge. In a typical application the deviation of electric resistance values within a Wheatstone bridge should be better than 0.1 \%. This demand is satisfied through a two step process with the processing steps: laser patterning of the sensor layout and equalisation of the electric resitance value through a trimming process. We found an inverse proportional dependency between conductor width and deviation of resistance values within a sensor bridge after laser patterning. The resistor deviation could be decreased up to a factor of 15 by a subsequent trimming procedure. Laser patterning and trimming can be accomplished with the same machining setup. Thus, laser processing is a promising approach for manufacturing of thin film strain sensors on component surfaces with high throughput and a small number of processing steps.