Fine powder ferrite for multilayer chip inductors

Abstract
Ni-Cu-Zn ferrite co-fired with Ag internal conductor below 900°C is very important for achieving a good quality and cost effective multilayer chip inductor. In this work, optimized processes were obtained to reduce the sintering temperature without deterioration of magnetic properties of ferrite. The main composition we used for low permeability ferrite was Fe2O3(48-50 mol%), NiO(40~50 mol%) with the rest of CuO and ZnO. The results manifested that the ferrite powder can be pulverized to fine particle size with 0.2~0.5 micron. Preliminary compensation of Fe2O3 make the ferrite easier to densify at 900°C, sintered density of 5.15 g/cm3 can be reached, and has good electromagnetic characteristics and higher Q factor