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Towards highly conductive silver pastes for LTCC power electronics

: Eberstein, M.; Kretzschmar, C.; Seuthe, T.; Marcinkowski, M.; Ihle, M.; Ziesche, S.; Partsch, U.; Gora, F.

Fulltext urn:nbn:de:0011-n-2171588 (335 KByte PDF)
MD5 Fingerprint: 89997570bfa2c02b892a91bad6dcf29f
Created on: 31.10.2012

International Microelectronics and Packaging Society -IMAPS-:
IMAPS 2011, 44th International Symposium on Microelectronics. Proceedings. Vol.2 : Long Beach, California, USA, 9 - 13 October 2011
Red Hook, NY: Curran, 2012
ISBN: 978-1-618-39850-5
International Symposium on Microelectronics (IMAPS) <44, 2011, Long Beach/Calif.>
Conference Paper, Electronic Publication
Fraunhofer IKTS ()
silver powder; silver paste; sintering; LTCC; power electronics; resistivity

The realization of high current conductors in LTCC multilayer architectures was studied. By mixtures of spherical silver powders, maximum tap densities above 7 g/cm3 could be obtained. On pressed cylinders a good correlation between tap density and total shrinkage was found. Pastes were made of the highly packed silver powders and detailed investigations regarding paste sintering kinetics and interactions between paste ingredients among one another as well as between paste ingredients and LTCC substrates were made. The pastes did not show a pronounced correlation between tap density and total densification. With increasing solid content of the pastes, the shrinkage printed-dry, the shrinkage dry-fired and the specific sheet resistance decreases. These findings can be used to control the filling degree of channels or grooves as well as the properties of the fired conductor. Expansion effects of the pure silver powders during sintering could be correlated to gas pressure effects, whereby there are obviously different kinds of gas formation in fine and coarse powders. Avoiding of camber of freely sintered LTCC should be attained if new LTCC materials are showing different sintering behavior, e. g. strong and early crystallization building of diffusion barriers or the possession of a glass phases which will not incorporate silver oxide. Research on this target should be done. The realization of high current conductors in constrained sintered LTCC was successfully shown. A paste comparable to standard values for direct copper bond (DCB) substrates with a thickness 35 μm of 0,48 mOhm/sq is introduced.