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54 SMT Magazine • June 2015 eVenT ReVIeW: (eMPS-6) continues with astronauts on board the International Space Station as it passes over Europe. Dr. Giles Humpston of Cambridge Nano- therm Ltd, UK, kicked off the workshop session related to circuit technologies. Nanotherm was founded in 2010 and produces nanoceramic coatings on various aluminium alloys. These coatings are dense and have a high breakdown voltage ideal for electronic applications. The nanoceramic layer can be made to vary in co- lour from ivory-white to black (dependent on the composition of the aluminium alloy: the darker coatings are made on copper-contain- ing aluminium alloys such as AA2024, and the white coatings are produced on purer grades of alloy). Inorganic PCBs can be manufactured from the ceramic-coated aluminium by adher- ing copper foil to the top surface of the nanoc- eramic. Such PCBs have a thermal conductiv- ity of 115 W per mK. Assembly of components to these PCBs (with pre-drilled holes) is similar to the component assembly of conventional epoxy or polyimide-glass fibre PCBs. This fully inorganic substrate can operate to 350 o C, and there is no outgassing-under-vacuum; with such a high thermal conductivity it is expected that this novel material will find many applica- tions during the design of spacecraft electron- ics, combustion monitoring systems and craft heading to the inner planets, Mercury and Ve- nus. The following presentation was made by Ilknur Baylakoglu of the Saturn Engineering and Training Consultancy, Ankara, Turkey. She stressed the need for reliable PCBs for space mis- sions. The manufacture of these conventional PCBs can involve about 180 individual process steps. Modern spacecraft PCBs are becoming smaller with increasing component density; new components are introduced early, possibly without sufficient reliability testing, and this combination is a potential driver for failure. The European space industries ECSS standards covering PCBs, such as the design rules, choice of materials and the qualification of manufac- turing lines were described. Detailed examples were given of PCB failure modes, particularly those involving plated through vias (PTVs). Baylakoglu characterized the base laminates in terms of glass transition temperature, mechani- cal properties and other moduli. This well-fo- cused presentation concluded with a series of photomicrographs showing the need for con- tamination-free production lines in order to ob- viate the growth of conductive anodic filaments and other electrical short circuit occurrences. Dave Davitt from COMDEV, Canada, a global company manufacturing space hardware for communications, space science and remote sensing satellites, gave an interesting talk that focused on the use of passive electronics for low-risk satellite payloads. He described coaxial and stripline circuits for microwave devices and explained the difficulties faced for the electrical signal transition from these circuits to adjacent hardware. The RF VIA approach developed by COMDEV was outlined, together with the need for matched impedance. The circuit laminating difficulties often encountered were explained. Also, a series of manufacturing defects were highlighted by means of metallographic sec- artICle Figure 1: Pre-drilled aluminium panel, processed by the nanotherm method to covert substrate to nanoceramic.

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