TY - JOUR A1 - Mieller, Björn A1 - Naghib Zadeh, Hamid A1 - Rabe, Torsten T1 - Improved co-firing of ferrite and dielectric tape based on master sintering curve predictions and shrinkage mismatch calculations JF - Journal of the American ceramic society N2 - Co-firing of low temperature co-fired ceramics (LTCC) and functional ceramics like ferrites is a promising approach to increase the level of integration in future microsystems, and to create new applications for LTCC technology. Besides the development of compatible material combinations, the configuration of the sintering process is an important issue for successful co-firing. A method is presented to derive the linear shrinkage mismatch of a material combination based on density data calculated from the master sintering curves (MSCs) of the individual materials. The influence of the firing profile on the constraint in the combined multilayer can be anticipated using this method. To investigate and improve the co-firing of ferrite and dielectric tape, the shrinkage mismatch with respect to heating rate was studied. A significant reduction of shrinkage mismatch was found for increased heating rates. The calculated results are verified by lateral shrinkage measurements on combined laminates. PY - 2013 DO - https://doi.org/10.1111/jace.12179 SN - 0002-7820 SN - 1551-2916 N1 - Geburtsname von Mieller, Björn: Brandt, B. - Birth name of Mieller, Björn: Brandt, B. VL - 96 IS - 3 SP - 726 EP - 730 PB - Blackwell Publishing CY - Malden AN - OPUS4-27955 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rabe, Torsten A1 - Naghib Zadeh, Hamid A1 - Glitzky, Carsten A1 - Töpfer, J. T1 - Integration of Ni-Cu-Zn ferrite in low temperature Co-fired ceramics (LTCC) modules JF - International Journal of Applied Ceramic Technology N2 - Integration of magnetic functional components in LTCC circuit boards calls for co-firing of dielectric and ferrite tapes. Ni-Cu-Zn ferrites with permeability of µ = 900 were fully densified at the standard LTCC sintering temperature of 900°C. Co-firing of this ferrite with dielectric tapes requires the adaptation of the shrinkage behavior of the materials as well as the thermal contraction during the cooling period – especially in the temperature range below the transformation point of the glass phase of the dielectric tape. To match these preconditions, a new dielectric LTCC material with steep sintering curve and high thermal expansion coefficient was designed. Sintered multilayer laminates composed of Ni-Cu-Zn ferrite and tailored dielectric tapes are free of cracks and possess no open porosity. No significant interdiffusion between the ferrite and dielectric tapes was found using microprobe analysis. Pure ferrite laminates show homogeneous microstructure with large grains up to 50 µm in diameter. However, growth of ferrite grains does not take place near the interface between ferrite and release or dielectric tapes. There is a strong correlation between permeability and volume fraction of large ferrite grains. Compared to pure ferrite laminates the permeability of co-sintered Ni-Cu-Zn ferrite layers is drastically reduced to 400, that is a decrease of more than 50%. PY - 2012 DO - https://doi.org/10.1111/j.1744-7402.2011.00712.x SN - 1546-542X SN - 1744-7402 VL - 9 IS - 1 SP - 18 EP - 28 PB - American Ceramic Soc. CY - Westerville, Ohio AN - OPUS4-25544 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Naghib Zadeh, Hamid A1 - Rabe, Torsten A1 - Karmazin, R. T1 - Integration of MnZn-ferrite tapes in LTCC multilayer JF - Journal of electroceramics N2 - For co-firing of MnZn-ferrite tapes and LTCC dielectric tapes, the sintering shrinkage curves and the coefficient of thermal expansion of ferrite and dielectric tapes were matched. Highly densified embedded ferrite without any cracks could be manufactured by co-firing at 900 °C in nitrogen atmosphere. However, the permeability of MnZn-ferrite co-fired between dielectric tapes is significantly reduced (µ´=100) compared to that of the separately sintered ferrite (µ´=500). Changes in the phase stability and microstructure of MnZn-ferrite were investigated to explain the permeability reduction in the embedded ferrite. It is supposed that early densification of the dielectric tapes on the top and bottom of the ferrite layer prevent the gas exchange during sintering which is necessary for (Mn,Zn)Fe2O4 spinel formation. As a result, high amount of Fe2O3 secondary phase and a Mn-rich spinel phase with low permeability remain in the embedded ferrite layer. KW - LTCC KW - MnZn-ferrite KW - Co-firing PY - 2013 DO - https://doi.org/10.1007/s10832-013-9800-5 SN - 1385-3449 SN - 1573-8663 VL - 31 IS - 1-2 SP - 88 EP - 95 PB - Kluwer Acad. Publ. CY - Boston, Mass. [u.a.], USA AN - OPUS4-29385 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Töpfer, J. A1 - Hesse, J. A1 - Bierlich, S. A1 - Barth, S. A1 - Capraro, B. A1 - Rabe, Torsten A1 - Naghib Zadeh, Hamid A1 - Bartsch, H. T1 - Integration of Ni-Cu-Zn and hexagonal ferrites into LTCC modules: Cofiring strategies and magnetic properties JF - Journal of the Japan society of powder and powder metallurgy = Funtai-oyobi-funmatsu-yakin N2 - We have studied the integration of Ni-Cu-Zn ferrite spinels as well as substituted hexagonal Co2Y-and M-type ferrites into LTCC (Low Temperature Ceramic Co-firing) modules. The cofiring behavior and the magnetic properties of these materials were investigated and evaluated for multilayer applications. Ni-Cu-Zn ferrites exhibit permeabilities of µ=300–500 for operating frequencies in the MHz range. Cu-substituted Y-type ferrites Ba2Co2-x-yZnxCuyFe12O22 in combination with sintering additives display sufficient shrinkage and densification at 900°C. A permeability of µ=10 is observed; however, substituted Co2Y-type ferrites do not exhibit long-term stability at 900°C. Co/Ti-substituted M-type ferrites BaFe12-2yCoyTiyO19 (y=1.2) with planar magneto-crystalline anisotropy exhibit excellent soft magnetic behavior. Using sintering additives, complete densification is reached at 900°C and a permeability of µ=15 and a resonance frequency of larger than 1?GHz are observed. Integration of ferrite multilayer inductor components into LTCC modules using free and constrained cofiring technologies is demonstrated. KW - Ferrites KW - Cofiring KW - LTCC modules KW - Permeability PY - 2014 UR - https://www.jstage.jst.go.jp/article/jjspm/61/S1/61_S214/_pdf DO - https://doi.org/10.2497/jjspm.61.S214 SN - 0532-8799 SN - 1880-9014 VL - 61 SP - Suppl. S1, S214 EP - S217 PB - Ky¯okai CY - Ky¯oto AN - OPUS4-31045 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Naghib Zadeh, Hamid A1 - Glitzky, Carsten A1 - Österle, Werner A1 - Rabe, Torsten T1 - Low temperature sintering of barium titanate based ceramics with high dielectric constant for LTCC applications JF - Journal of the European Ceramic Society N2 - The sintering temperature of BaTiO3 powder was reduced to 900 °C due to the ZnO-B2O3-Li2O-Nb2O5-Co2O3 addition. Excellent densification was achieved after sintering at 900 °C for 2 h. The low sintering temperature of newly developed capacitor materials allows a co-firing with pure silver electrodes. The dielectric constant and the temperature stability of the dielectric constant are strongly correlated with the composition of the ZnO-B2O3-Li2O additives. A high dielectric constant up to 3000 and a dielectric loss less than 0.024 were measured on multilayer capacitors sintered at 900 °C with silver inner electrodes. KW - BaTiO3 and titanates KW - Capacitors KW - Dielectric properties KW - LTCC PY - 2011 DO - https://doi.org/10.1016/j.jeurceramsoc.2010.10.003 SN - 0955-2219 SN - 1873-619X VL - 31 IS - 4 SP - 589 EP - 596 PB - Elsevier Ltd. CY - Oxford AN - OPUS4-22886 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Naghib Zadeh, Hamid A1 - Glitzky, Carsten A1 - Dörfel, Ilona A1 - Rabe, Torsten T1 - Low temperature sintering of barium titanate ceramics assisted by addition of lithium fluoride-containing sintering additives JF - Journal of the European Ceramic Society N2 - By addition of LiF-containing sintering additives to commercial BaTiO3 powder, more than 98% of the theoretical density was reached at a sintering temperature of 900 °C both on powder compacts and laminates. Dielectric measurements were performed on ceramic samples in the temperature and frequency ranges from -20 °C to 125 °C and from 103 to 106 Hz, respectively. High relative permittivity (εr ~ 3160) and low dielectric loss (tan δ ~ 0.014) were measured for tapes of the favoured material. The breakdown strength for tapes with a thickness of about 80 µm is 30 kV/mm. The microprobe analysis showed, that no interfacial reaction between the dielectric layer and the Ag-electrode had occurred. The newly developed barium titanate ceramics completely densifying at 900 °C turned out to be promising for integration of buried capacitors in LTCC multilayers. KW - LTCC KW - BaTiO3 KW - LiF KW - Capacitors PY - 2010 DO - https://doi.org/10.1016/j.jeurceramsoc.2009.07.005 SN - 0955-2219 SN - 1873-619X VL - 30 IS - 1 SP - 81 EP - 86 PB - Elsevier CY - Oxford AN - OPUS4-20133 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -