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Development of High Permeability Core Materials for Embeddable Inductors in Flexible Organic Substrates

  • C. K. Liu (a1), P. L. Cheng (a1), S. Y. Y. Leung (a1), T. W. Law (a1) and D. C. C. Lam (a1)...


Capacitors, resistors and inductors are surface mounted components on circuit boards, which occupy up to 70% of the circuit board area. For selected applications, these passives are packaged inside green ceramic tape substrates and sintered at temperatures over 700°C in a co-fired process. These high temperature processes are incompatible with organic substrates, and low temperature processes are needed if passives are to be embedded into organic substrates. A new high permeability dual-phase Nickel Zinc Ferrite (DP NZF) core fabricated using a low temperature sol-gel route was developed for use in embedded inductors in organic substrates. Crystalline NZF powder was added to the sol-gel precursor of NZF. The solution was deposited onto the substrates as thin films and heat-treated at different temperatures. The changes in the microstructures were characterized using XRD and SEM. Results showed that addition of NZF powder induced low temperature transformation of the sol-gel NZF phase to high permeability phase at 250°C, which is approximately 350°C lower than transformation temperature for pure NZF sol gel films. Electrical measurements of DP NZF cored two-layered spiral inductors indicated that the inductance increased by three times compared to inductors without the DP NZF cores. From microstructural observations, the increase is correlated with the changes in microstructural connectivity of the powder phase.



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1. Dakeya, Y, et al., “Chip multilayer antenna for 2.45 GHz-band application using LTCC technology”. 2000 IEEE MTT-S International Microwave Symposium Digest, IEEE Part vol 3, p.16931696, 2000.
2. Sheen, Jyh-Wen and Tang, Ching-Wen, “LTCC-MLC balun for WLAN/Bluetooth”. 2001 IEEE MTT-S International Microwave Sympsoium Digest IEEE Part vol 1, p.315318, 2001.
3. Park, J.Y. and Allen, M.G., “Integrated electroplated micromachined magnetic devices using low temperature fabrication processes”. IEEE Transactions on Electronics Packaging Manufacturing, vol.23, p. 4855, 2000.
4. Tang, S.C., Hui, S.Y.R., and Chung, H.S.H., “A low-profile power converter using printed-circuit board (PCB) power transformer with ferrite polymer composite”. IEEE Transactions on Power Electronics, vol. 16, p.493498, 2001.
5. Park, J.Y. and Allen, M.G., “Packaging compatible micromagnetic devices using screen printed polymer/ferrite composites”. International Journal of Microcircuits & Electronic Packaging, vol 21, p. 243252, 1998.
6. Park, J.Y., Lagorce, L.K., and Allen, M.G., “Ferrite-based integrated planar inductors and transformers fabricated at low temperature”. IEEE Transactions on Magnetics, vol. 33, p. 33223324, 1997.
7. Park, J.Y. and Allen, M.G., “Low temperature fabrication and characterization of integrated packaging-compatible, ferrite-core magnetic devices”. Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC. V. 1, p. 361367, 1997.
8. Arshak, K.I., Ajina, A., and Egan, D., “Development of screen-printed polymer thick film planner transformer using Mn-Zn ferrite as core material”. Microelectronics Journal, vol. 32, p. 113116, 2001.
9. Liu, C.K.; Law, T.W.; Cheng, P.L.; Chong, I.T.; Lam, D.C.C., “Low temperature processing and electrical properties of embedded ferrite-cored inductor”, ECTC, 2002. Proceedings. 52nd p. 490494, 2002.
10. Bae, S.Y., et al., “Magnetic properties of sol-gel derived Ni-Zn ferrite thin films”. Journal de Physique IV, vol.8, p. 261264, 1998.
11. Hoffman, C., “Design, fabrication, and testing of sol-gel magnetic devices”. Electrical Insulation Conference and Electrical Manufacturing & Coil Winding Conference. Proceedings, p.4752, 1999.

Development of High Permeability Core Materials for Embeddable Inductors in Flexible Organic Substrates

  • C. K. Liu (a1), P. L. Cheng (a1), S. Y. Y. Leung (a1), T. W. Law (a1) and D. C. C. Lam (a1)...


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