Micross

Abstract Preview

Here is the abstract you requested from the CICMT_2011 technical program page. This is the original abstract submitted by the author. Any changes to the technical content of the final manuscript published by IMAPS or the presentation that is given during the event is done by the author, not IMAPS.

Z-, Y- and M-Type Hexagonal Ferrites for High-Frequency Inductive Multilayer Devices
Keywords: hexagonal ferrites, multilayer inductors, high frequency
Co-containing hexagonal ferrites can be used as soft magnetic materials for multilayer inductors for high frequency applications up to 3 GHz. We report on the preparation, thermal stability and magnetic properties of Z-, Y- and M-type hexagonal ferrites. Co2Z-type ferrite Ba3Co2Fe24O41 and iron excess Ba3Co2-yFe24+yO41 (0 < y < 0.8) were prepared by an oxalate co-precipitation technique and the mixed oxide route. Single phase Z-type ferrites were obtained after sintering at 1300°C. The permeability of a sample with y = 0.6 sintered at 1300°C is µ = 30 with a resonance frequency of 1 GHz. The addition of Bi2O3 as sintering aid shifts the maximum shrinkage down to 950°C and dense samples were sintered at 950°C; however, their permeability is only µ = 3…5. It is shown that Co2Z ferrites are not stable under LTCC conditions. Cu-substituted Z-type ferrites Ba3Co2-xCuxFe24O41 exhibit enhanced sintering ability, but sintering at 950°C also results in low permeability. Y-type hexagonal ferrites Ba2Co2-x-yZnxCuyFe12O21 were prepared at 1100°C and a permeability of µ = 20 was found for x = 1.1 and y = 0.8. Samples with Bi2O3 addition were sintered at 950 and 900°C exhibiting a permeability of µ = 10. Similar values were measured for M-type ferrites BaFe12-2yCoyTiyO19 with y = 1.2 which were sintered at 900°C using additives. Co/Ti co-substitution is an essential prerequisite for tailoring the magneto-crystalline anisotropy. Co/Ti- substituted M-type materials are stable under LTCC conditions. Ferrite multilayer devices were fabricated by screen printing coils onto ferrite tapes, stacking and lamination. Firing was performed between 1300°C and 900°C, i.e. at HTCC and LTCC conditions, respectively. The inductance behavior of the devices was evaluated and modeled. It is shown that hexagonal ferrites are suitable materials for the high-frequency multilayer inductors; however, Y- and M-type ferrites are preferred for LTCC-type inductors (cofiring at 900°C) with Ag metallization.
J. Topfer, Professor
University of Applied Sciences Jena
Jena, Thuringia 07745,
Germany


CORPORATE PREMIER MEMBERS
  • Amkor
  • ASE
  • Canon
  • EMD Performance Materials
  • Honeywell
  • Indium
  • Kester
  • Kyocera America
  • Master Bond
  • Micro Systems Technologies
  • MRSI
  • NGK NTK
  • Palomar
  • Plexus
  • Promex
  • Qualcomm
  • Quik-Pak
  • Raytheon
  • Specialty Coating Systems