METAL-MATRIX COMPOSITE PACKAGING OF MICROWAVE CIRCUITRY

Metal matrix composite (MMC) materials have been of interest in many s ectors of industry for some time because of their potential enhanced s trength, stiffness, wear resistance, fatigue resistance, and tailorabl e thermal conductivity and coefficient of thermal expansion. The adopt ion of such materials in products has, however, been relatively slow, mostly because of the belief that the raw composite material is costly and difficult to machine. To try to separate fact from fiction, via a programme of considered risk reduction, the design and mnnufacture of a demonstrator box, housing microwave circuitry, was undertaken at GE C-Marconi Research Centre. Using design rules developed during the pro ject, a box using a 70% volume fraction silicon carbide-in-aluminium m atrix was machined, plated, soldered, assembled and tested to produce what the authors believe to be the first such application of its type in the UK and probably in Europe. Evidence was obtained during the pro ject that the costs associated with the material and its machining wer e descending rapidly to a level that makes its use viable, albeit in s pecialist applications