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U. Schmid, A. Bittner:
"LTCC as Advanced Substrate Material for Miniaturized Devices and Systems";
Vortrag: 35th International Conference of IMAPS - CPMT IEEE Poland, Gdansk-Sobieszewo, Poland (eingeladen); 21.09.2011 - 24.09.2011; in: "Conference Proceedings", (2011), ISBN: 978-83-932464-0-3; S. 55 - 58.

Low Temperature Co-fired Ceramics (LTCC) is an attractive technology platform for the realization of miniaturized devices and systems with geometrical dimensions down to the meso-scale range. Besides the well-established application as substrate material for electronic circuits, it can be used for e.g. sensor elements operated in harsh environment, so that we focus within this paper on scenarios expanding the state-of-the art potential of LTCC. In the field of high frequency applications such as radar systems operated up to 79 GHz a wet chemical etching technique is introduced in order to generate regions with different permittivity in one single LTCC layer. By selectively dissolving crystallographic phases out of the composite glass-ceramic a nano-scaled porous structure can be formed enabling air to penetrate in the LTCC body and hence, to decrease the effective dielectric constant. Thin film technology is recommended on LTCC substrates when targeting a proper realization of RF structures as a high lateral resolution in the μm-range is required. Therefore, different thin film metallization systems based on silver, molybdenum or titanium/platinum are comparatively evaluated on LTCC substrates taking into account their specific properties such as the surface roughness which in turn has a direct impact on the microstructure of the thin films. In this context, LTCC is discussed as an attractive technology platform for the realization of sensor devices operating in harsh environments. Both a high mechanical strength and an enhanced chemical
inertness are fundamental requirements for the realization of flow sensors integrated in the injection nozzle of Common-Rail diesel engines where the injection pressure ranges up to 1350 bar or even higher.

LTCC, thin film metallization systems, substrate effect, flow sensor, high frequency, radar systems