Multilayer ferrite inductors for the use at high temperatures

Abstract

Purpose

This paper aims to investigate the usability of the nickel copper zinc ferrite with the composition Ni_0.4Cu_0.2Zn_0.4Fe_1.98O_3.99 for the realization of high-temperature multilayer coils as discrete components and integrated, buried function units in low temperature cofired ceramics (LTCC).

Design/methodology/approach

LTCC tapes were cast and test components were produced as multilayer coils and as embedded coils in a dielectric tape. Different metallization pastes are compared. The properties of the components were measured at room temperature and higher temperature up to 250°C. The results are compared with simulation data.

Findings

The silver palladium paste revealed the highest inductance values within the study. The measured characteristics over a frequency range from 1 MHz to 100 MHz agree qualitatively with the measurements obtained from toroidal test samples. The inductance increases with increasing temperature and this influence is lower than 10%. The characteristic of embedded coils is comparable with this of multilayer components. The effective permeability of the ferrite material reaches values around 130.

Research limitations/implications

The research results based on a limited number of experiments; therefore, the results should be verified considering higher sample sizes.

Practical implications

The results encourage the further investigation of the material Ni_0.4Cu_0.2Zn_0.4Fe_1.98O_3.99 for the use as high-temperature ferrite for the design of multilayer coils with an operation frequency in the range of 5-10 MHz and operation temperatures up to 250°C.

Originality/value

It is demonstrated for the first time, that the material Ni_0.4Cu_0.2Zn_0.4Fe_1.98O_3.99 is suitable for the realization of high-temperature multilayer coils and embedded coils in LTCC circuit carriers with high performance.

Citation

Bartsch, H., Thiele, S., Mueller, J., Schabbel, D., Capraro, B., Reimann, T., Grund, S. and Töpfer, J. (2020), "Multilayer ferrite inductors for the use at high temperatures", Microelectronics International, Vol. 37 No. 2, pp. 73-78. https://doi.org/10.1108/MI-11-2019-0072