Preparation and electromagnetic properties of NiCuZn ferrites and multilayer chip inductors

Abstract

(Ni0.2Cu0.2Zn0.6O)1.02(Fe2O3)0.98 based ferrites with combined B2O3-WO3-Co2O3 dopings were synthesized through solid state reaction. Subsequently, high-performance NiCuZn green tapes and multilayer chip inductors were fabricated via non-aquous tape casting. The results showed that an appropriate Co2O3 doping in the B2O3-WO3 contained NiCuZn ferrites could refine the crystalline grains, and reduce the permeability, and increase the Q factor of the ferrites. NiCuZn ferrite with 0.03 wt% B2O3, 0.7 wt% WO3, and 0.60 wt% Co2O3 sintered at 900 °C showed excellent electromagnetic properties: μi = 424.0 at 0.1 MHz, Q factor = 127.0, Bs = 283.5, Br = 79.5, Hc = 52.3, and a good co-firing compatibility with Ag electrodes. The resulting NiCuZn multilayer chip inductor (6 ×6 ×2 mm in dimention) exhibited an inductance of 26.0 μH (0.1 MHz, 0.25 V), and a Q factor of 8.5, and a DC superposition current of about 984 mA, thus guaranteeing this NiCuZn material a promising candidate for the LTCF applications.