A novel lightweight microwave packaging technology

Spray-formed alloys of silicon-aluminum have been used as the basis for a new microwave packaging technology for aerospace applications, taking advantage of the low thermal expansivity, high thermal conductivity and unusually low density of these materials. These high-silicon Si-Al alloys are relatively easy to machine to tight tolerances using standard workshop facilities and they can be electroplated with relative ease. Demonstrator microwave amplifier modules designed for space application have been successfully produced and tested. The packages comprise kovar side-walls supplied with appropriate RF and DC feedthroughs, which are bonded to the Si-Al base by diffusion soldering. This package configuration provides rigid bases for the circuitry and a weight saving of typically 30% over all-kovar packages.