Mounting alumina to a housing

Anyone have any good new ways for mounting alumina ceramic to a housing that can withstand the thermal expansion. I am familiar with Kovar, Silicon Aluminum, and Titanium housing materials. Anything else out there, expecially something that is dirt cheap or can be cast without machining for a housing material? Also, are there any really ductile mounting methods, like new conductive epoxies, that can stand a lot of surface roughness, take up all of the thermal expansion, and still have good electrical conductivity up to 20 GHz?

I have heard this stuff is very thermally conductive. I have used other silver epoxies on alumina with but not to 20 GHz. There was a silver epoxy that had long term failure (about 3-5 years) in conductivity so be sure to get that data from the manufacturer.


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