Prof. Knut Aasmundtveit
Vestfold University College, Norway
August 23, 2011 | 12:00 to 01:00 | 540 Cory Hall, DOP Center Conference Room
Host: Debbie Senesky
Solid-Liquid InterDiffusion (SLID) bonding is a novel bonding technique for microsystems. The technique uses thin layers of a two-metal system: a high temperature-melting metal (e.g., Cu or Au) and a low temperature-melting metal (e.g., Sn). Layer thicknesses are designed so that all the Sn (or similar) is consumed in the bonding process and converted to high temperature-melting intermetallic compounds. Thus, the bonding can take place at a moderate process temperature (above the melting point of Sn, similar to a soldering process), whereas the final bond can withstand high temperatures (up to 500C to 700C). SLID bonds are therefore very promising for high temperature applications as well as for applications where the same process temperature needs to be repeated. We have performed Cu-Sn and Au-Sn SLID bonding on various model systems. Very strong bonds are obtained and the bonds are experimentally verified to be solid at temperatures higher than 400C. Cross-section analysis shows uniform bonds with single intermetallic phases, identified as the desired phases Cu_3Sn and Au_5Sn, respectively. SiC components for high temperature applications have been bonded to Si_3N_4 substrates using Au-Sn SLID bonding. The samples have undergone high temperature thermal cycling. Despite the CTE mismatch (chip-to-substrate), the components show excellent bonding strength after thermal cycling. SLID bonding is therefore an excellent candidate for bonding & interconnect of SiC and other high temperature components.
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