Electrode Effect on NTC Planar Thermistor Volume Resistivity

Thick film planar thermistors, such as rectangular, sandwich, multilayer, segmented and interdigitated were printed with low temperature NTC paste called NTC 3K3 95/2 (EI IRITEL). Their resistivity was analyzed as a function of volume resistivity variations due to electrode effect (diffusion of P_dA_g into NTC layer) and variation of geometrical parameters such as length l, witdh w, thickness d, number of segments n. Using experimental data, a model was obtained for analyzing the diffusion effect on volume resistivity by a simple fitting procedure. The good match between calculated and experimental data enabled inclusion of that formula in the total physical/mathematical model of thermistor resistivity