TY - CONF A1 - Rabe, Torsten A1 - Naghib Zadeh, Hamid A1 - Glitzky, C. A1 - Töpfer, J. T1 - Integration of Ni-Cu-Zn ferrite in LTCC-modules T2 - CICMT 2011 - 7th International conference and exhibition on ceramic interconnect and ceramic microsystems technologies (Proceedings) 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 p=900 were developed which can be fully densified at the Standard LTCC sintering temperature of 900 °C. Successful co-firing of this ferrite with dielectric tapes requires the adaptation of the shrinkage behavior of the materials as well as the thermal expansion during the cooling period - especially in the temperature range below the transformation point of the glassy 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 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 by EDX measurements. Compared to pure ferrite laminates the permeability of co-sintered Ni-Cu-Zn ferrite layers is drastically reduced to 400, i.e. a decrease of more than 50 %. To investigate the origin of this permeability reduction, Ni-Cu-Zn ferrite laminates were sintered separately, and in combination with alumina release tapes or dielectric tapes, respectively. SEM and EDX analysis of co-fired laminates reveal differences in the ferrite grain growth behavior. Ferrite laminates with homogeneous microstructure and grain size up to 50 pm exhibit large permeability. 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 high permeability and volume fraction of large ferrite grains. Regions of fine and coarse grains inside the ferrite layers show different bismuth concentration; the Bi-content is larger in regions of fine ferrite grains. T2 - CICMT 2011 - 7th International conference and exhibition on ceramic interconnect and ceramic microsystems technologies CY - San Diego, CA, USA DA - 05.04.2011 KW - LTCC KW - Co-firing KW - Ferrite KW - Shrinkage behavior KW - Constrained sintering KW - Keramische Multilayer KW - Grenzflächenreaktion PY - 2011 SN - 0-930815-92-0 SP - 000266 EP - 000275 PB - IMAPS, International Microelectronics and Packaging Society AN - OPUS4-25072 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Naghib Zadeh, Hamid A1 - Rabe, Torsten A1 - Toepfer, J. A1 - Karmazin, R. T1 - Co-firing of LTCC modules with embedded ferrite layers T2 - EMPC-2011 - 18th European microelectronics & packaging conference (Proceedings) N2 - Further miniaturization of electronic packaging calls for integration of magnetic functional components into LTCC modules. For integration of magnetic function into LTCC, low fired MnZn- and NiCuZn-ferrites which can be fully densified at the standard LTCC sintering temperature of 900°C were developed. To co-fire these ferrite tapes with dielectric tapes the sintering shrinkage and the coefficient of thermal expansion of ferrite and dielectric tapes must be matched. For each ferrite material a new LTCC dielectric material was designed. The embedded ferrite tapes into new LTCC dielectric tapes can be sufficiently densified during co-firing at 900°C without any cracking. Compared to separately sintered ferrites the permeability of embedded ferrite tapes is reduced. For embedded NiCuZn ferrites permeabilities between 230 and 570 (at 2 MHz) according to the thickness of the embedded ferrite layer were measured. For embedded MnZn ferrites a permeability of 300 was measured. T2 - EMPC-2011 - 18th European microelectronics & packaging conference CY - Brighton, UK DA - 12.09.2011 KW - LTCC KW - Co-firing KW - Ferrite PY - 2011 SN - 978-0-9568086-0-8 IS - TuA2 SP - 1 EP - 6 AN - OPUS4-25021 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 -