Structural and electrical properties of perovskite ruthenate-based lead-free thick film resistors on alumina and LTCC

CaRuO3 perovskite-based lead-free thick-film resistors (TFRs) were prepared on 96%-alumina and Low Temperature Co-fired Ceramic (LTCC) substrates. The microstructure evolution, possible interactions, and electrical properties of resistors were investigated. The hot and cold TCR values of all the resistors were measured in the temperature range (+20 to +120 ° C) and (+20 to -120 ° C), respectively. TFRs with 25% by vol. of CaRuO3 on alumina exhibit a sheet resistance R-s = 5 k Ohm/sq. with hot and cold TCR of 225 and 470 ppm/° C respectively, whereas the same composition gives 1.2 k Ohm/sq., 16.5 k Ohm/sq. and 0.7 k Ohm/sq. for co-fired, post-fired resistors on LTCC and buried resistors, respectively. The hot (HTCR) and cold (CTCR) values were evaluated; HTCR = 190 ppm/° C and CTCR = 314 ppm/°C were found for co-fired structures; HTCR = 216 ppm/degrees C and CTCR = 205 ppm/°C for post-fired samples and HTCR = 520 ppm/°C and CTCR = 350 ppm/° C for buried in LTCC structures.