Future trends in materials for lightweight microwave packaging

The set of properties required for microwave packaging materials intended for aerospace applications is discussed in relation to the current range of materials that are commercially available. Initiatives are being taken to replace kovar, the established packaging material, with substitutes which are lighter, stiffer and offer superior heat‐sinking. Promising in this regard are new family of beryllium‐beryllia and also silicon‐aluminium (Si‐Al) alloys high in silicon, with ratios of constituents chosen such that they optimally complement gallium arsenide MMIC devices and alumina circuit boards. Both types of material are relatively easy to machine and electroplate. Demonstrator microwave amplifier modules incorporating the Si‐Al alloys have been designed for space applications and have been successfully produced and tested. The manufacturing technology that has been developed for this purpose is described.