Characterisation of thick film resistor series for strain sensors

Some 10 kohm/sq. thick film resistors based on RuO2, ruthenates or a mixture of RuO2 and ruthenates, were evaluated for strain gauge applications. The resistors were fired at different temperatures to estimate the influence of firing temperature on the electrical characteristics. Temperature coefficients of resistivity (TCR), noise indices and gauge factors (GF) were measured. Microstructures of the thick film resistors were analysed by SEM. The results indicate that the microstructure of thick film resistors influences the gauge factors much more significantly than the “nature” of the conductive phase.