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A new LTCC (low-temperature cofired ceramic) system containing Al 2 O 3 platelets instead of conventional Al 2 O 3 particles as a filler material was investigated. As the Al 2 O 3 platelets were arranged parallel to the casting direction during tape casting and had preferred orientation in the green tape, the linear shrinkage of the green body took place mainly in the direction perpendicular to the platelet planes with just a little shrinkage in the horizontal without any external force during sintering. The intended anisotropic shrinkage of the new LTCC system made the constrained sintering of 10-mm-thick ceramic body possible, which decreased the sintering shrinkage tolerance in the x-y directions of the 10-mm-thick ceramic body from 0.5% to 0.05%. The new LTCC system showed equivalent electrical properties and remarkable physical properties in comparison with a conventional LTCC system.

In this paper, an ultra miniaturized transceiver module for Bluetooth applications using 3-D LTCC system-onpackage technology is presented. The proposed compact LTCC Bluetooth module is monolithically implemented with 0.5 mm thickness substrate embedding all passive components such as bandpass filter, balun, matching circuit, resistor, RF choke and bypass capacitor in order to reduce the overall size of module. The whole size of module is as small as 4.3 x 4.1 x 1.2 mm, which is the smallest size in the Bluetooth modules. The fabricated Bluetooth module reveals a transmit power of over 1 dBm and a sensitivity of -83 dBm. Index Terms -LTCC, embedded, Bluetooth978-1-4244-1780-3/08/$25.00

In this paper, the authors present the noise suppression performance using a decoupling capacitor which is embedded in an LTCC substrate. To embed high value capacitors (>20nF), a high K (over 500) material which can be co-fired with low K LTCC was developed successfully. Thin high K sheets under 10μm were co-laminated between low K sheets, which form the power and ground planes. Due to the short distance from the IC power pin to the decoupling capacitor, the ESL (Equivalent Series Inductance) is much lower than with surface mounted type capacitors, and so, SSN (Simultaneous Switching Noise) can be reduced significantly. To verify the noise suppression performance, we designed and fabricated a digital module using 100MHz CPLD (Complex Programmable Logic Device) on top of the LTCC substrate in which a 25nF decoupling capacitor was embedded. By measurement, we can see that SSN of CPLD on LTCC was reduced by 80% compared with designs that use surface mounted type 100nF capacitors. This embedded decoupling capacitor in LTCC (LEDC) can be useful for digital SiP (System In Package) to enhance noise performance and to reduce its footprint.