Low thermal resistivity adhesive bonding of ceramic substrates to high performance coolers for the fabrication of power MCMs

This paper describes the use of thermally conductive adhesives for the attachment of high power multi-chip modules (MCM) and liquid cooled heat sinks. Two thermal management concepts-the planar embedding technology and MCMs with die attach and wire bonding-were compared. Thermal simulation was used to demonstrate the advantages and limitations of the technologies. Thermal test multi-chip modules were assembled with different types of adhesives and the thermal performance quantified. In addition the interface resistance was measured and experimental design was used to confirm the adhesive bonding conditions. Tolerances of substrates and heat sinks are investigated. Junction-to-ambient thermal resistivities below 1.5 Wcm2/K were achieved with the planar embedding technology by applying 75 mu m thick Ag-, AlN- and diamond filled film adhesives. This is an advantage of up to 40% over the die-attach-on-substrate technology