Thick Film Ni-Ferrite Inductors

Abstract
Ni-ferrite inductors were realized in thick film multilayer technology on Al₂O₃ substrate using Pd/Ag conductive paste, Al₂O₃ dielectric paste and Ni-ferrite paste. Three different constructions of square spiral inductors were printed, fired and measured : "simple" spiral, "reverse" spiral and "outer" spiral. While "simple" spiral contains one conductive layer, the other two types have two conductive layers. Additional magnetic thick layers were placed on the bottom and the top of inductor constructions. Inductors were measured on the network analyzer in the HF range (up to x 100MHz). An original CAD, based on well known method of current images, was developed to predict and explain the experimental results. Obtained results indicate the possibility of using thick film spiral inductors in the HF range for the same application as the chip inductors, but except the fact that this type of inductors could be used as a discrete hybrid component, it could be directly incorporated in the hybrid circuits (such as filters etc.).