LTCC-compatible Multilayer Ferrites for Integrated Inductors
Ni-Cu-Zn and Mg-Cu-Zn ferrites were developed for the fabrication ofmultilayer ferrite inductors (MLFI) for monolithic or integrated inductors in complex LTCC modules. Ferrites with <50 mol％ Fe203 exhibit enhanced densification and shrinkage behavior. The magnetic properties of the ferrites can be tailored by proper selection of the Cu-concentration, (Ni,Mg)/Zn-ratio and sub-stoichiometry. Sub-micron powders prepared by milling show enhanced sintering activity and high density after firing at 900℃. Nano-size ferrite powders prepared by oxalate co-precipitation process also sinter to high density; maximum shrinkage already occurs at T<800℃. Mixtures of sub-micron and nanosized powders allow tailoring the shrinkage between 700-900℃.Dense samples with homogeneous microstructures and grain sizes of 2 um were prepared; the additive-free samples have a permeability of 800. Addition of up to 1 wt％ Bi2O3 tends to significantly influence the ceramic microstructure. Maximum permeability u=920 is observed for 0.37％ Bi203 with an inhomogeneous microstructure. Co2Z-type hexagonal ferrites for high frequency applications (1-2 GHz) were synthesized at 1300℃ as single phase materials with a permeability of μ=30. The shrinkage was adjusted to 950℃ by addition of sintering aids. Co2Z ferrite is not stable at 950℃ and partial ferrite decomposition is the origin of the reduction of permeability (μ=5). Ferrite tapes were processed to multilayer inductors. The integration of ferrite and dielectric LTCC tapes was studied. Co-firing of sandwiched laminates was achieved by adaptation of the shrinkage behavior and thermal expansion coefficients of both materials.
Ni-Cu-Zn ferrites hexagonal ferrites multilayer inductors LTCC integrated inductors
J.Topfer J.Murbe S.Kracunovska S.Barth B.Pawlowski T.Bartnitzek C.Glitzky T.Rabe
Univ.Applied Sciences Jena,Jena 07745,Germany Hermsdorfer Institut fiir Technische Keramik,Hermsdorf 07629,Germany VIA-Electronic GmbH,Hermsdorf 07629,Germany Federal Institute for Materials Research and Testing (BAM),Berlin 12205,Germany
国际会议
The 10th International Conference on Ferrites(2008中国国际铁氧体研讨会)
成都
英文
147-150
2008-10-10（万方平台首次上网日期，不代表论文的发表时间）