A silicon substrate adapted for large scale integrated electronic circuits upon a lower surface has its upper surface coated with a highly porous heat sink film. The film is composed of a porous metal, preferably aluminum, formed by vacuum deposition (evaporation or sputtering) at a high pressure of...http://www.google.com.au/patents/US4381818?utm_source=gb-gplus-sharePatent US4381818 - Porous film heat transfer
