Effects of a non-magnetic CuZn ferrite layer on cofiring and electrical properties of a low-fire, multilayer NiCuZn ferrite inductor

Stress development during cofiring a bi-layer laminate with a non-magnetic (Cu0.2Zn0.8O)–(Fe2O3)0.8 (CZF) and a magnetic (Ni0.25Cu0.25Zn0.5O)–(Fe2O3)0.75 (NCZF) ferrite layer has been investigated by measuring camber development and shrinkage rate difference. Development of camber follows a similar trend to that of linear shrinkage rate difference between CZF and NCZF. The sintering mismatch stress generated during cofiring is much less than those of sintering potentials, resulting in no cofiring defects observed at the interface of CZF/NCZF. Results of electrical and magnetic property measurements show that the multilayer NCZF inductor with an embedded CZF layer has a lower electrical resistance at high frequencies and less significant magnetic inductance reduction with increasing DC current than those of a pure multilayer NCZF inductor.