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Investigation of inhomogeneous shrinkages of partially crystallizing Low Temperature Co-fired Ceramics (LTCC)

: Lenz, Christian; Kappert, Sandro; Ziesche, Steffen; Neubert, Holger; Partsch, Uwe

International Microelectronics and Packaging Society -IMAPS-; American Ceramic Society -ACerS-, Westerville/Ohio:
11th IMAPS/ACerS International Conference and Exhibition on Ceramic Interconnect and Ceramic Microsystems Technologies, CICMT 2015 : Held 20 - 23 April 2015, Dresden, Germany
Red Hook, NY: Curran, 2015
ISBN: 978-1-5108-0456-2
International Conference and Exhibition on Ceramic Interconnect and Ceramic Microsystems Technologies (CICMT) <11, 2015, Dresden>
Conference Paper
Fraunhofer IKTS ()
LTCC; glass-ceramic composites; shrinkage fields; production yield; free sintering; partial crystallization

The aim of our study is an improved level of geometrical design fidelity of LTCC microsystems by consideration of location-dependent shrinkage under free sintering conditions. To achieve this, the commercial low temperature co-fired ceramic (LTCC) systems: DuPont GT 951, DuPont 9k7 and Heraeus CT 702 have been investigated experimentally with special regard to the local lateral shrinkage over a 4 inch x 4 inch substrate typically used for the fabrication in multiple panels. Partially crystallizing LTCC materials reveal a significant local dependence of the lateral shrinkage. This dependence is introduced as a shrinkage field. Furthermore, we present an approach for shrinkage field approximation and forecasting. Applied to shrinkage allowance, it allows for minimizing the geometrical deviations after sintering from designed dimensions. Alternatively to a design adapted to the forecasted shrinkage field, local shrinkage deviations can be minimized by sintering for homogeneous shrinkage. Detailed analyses of the DuPont GT 951 system indicate a strong influence of the temperature profile during the free sintering on the shrinkage field. By utilizing this influence, a homogenous shrinkage field can be achieved for optimized heating rate and dwell time at the peak temperature 850 °C.