Fine powder ferrite for multilayer chip inductors

Ni-Cu-Zn ferrite co-fired with Ag internal conductor below 900/spl deg/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 Fe/sub 2/O/sub 3/(48-50 mol%), NiO(40/spl sim/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/spl sim/0.5 micron. Preliminary compensation of Fe/sub 2/O/sub 3/ make the ferrite easier to densify at 900/spl deg/C, sintered density of 5.15 g/cm/sup 3/ can be reached, and has good electromagnetic characteristics and higher Q factor.<>