Low temperature TLP bonding of [Al.sub.2][O.sub.3]-ceramics using eutectic Au- alloys

In this study, [Al.sub.2][O.sub.3]-ceramics were joined via TLP bonding using interlayers of eutectic Au-12Ge (wt%) and Au-3Si (wt%) solder alloys, respectively, with a melting temperature of 361 and 363°C and Ni wetting layers. The Ni layers were part of a metallic multilayer coating (Ti/W/Ni) applied on the ceramic surface to ensure wetting and adhesion during the joining process. For comparison, a soldering process was performed as well by changing the multilayer structure to Ti/W/Au. With respect to the different joining processes the influence of the variation in wetting layers on the interface reactions, mechanical properties and re-melting temperature was analyzed by scanning electron microscopy, shear testing, and differential scanning calorimetry. It is shown that sound joint can be produced at a joining temperature of 400°C, achieving reasonable shear strength and re-melting temperatures more than 550°C above the initial melting temperature of the filler metal.