Date of Award
Raytheon has asked team S.H.I.E.L.D to design an enclosure for a Circuit Card Assembly (CCA) that is thermally conductive, able to prevent electromagnetic interference with other devices and is able to be produced using additive manufacturing. The enclosure needs to be thermally conductive to prevent the electronics on the circuit card from overheating. Because of all the other electrical devices that will be in the general vicinity, the enclosure will be to be electrically conductive to prevent any electrical interference with the other devices. And finally, the enclosure needs to be able to be produced using additive manufacturing because this will save Raytheon money, as well as give Raytheon flexibility when designing the enclosures. Flexibility in the design of the enclosures is important because there are a variety of different circuit card sizes and designs that need to be shielded.
Team S.H.I.E.L.D chose a specific enclosure design to focus on, which has a heat sink and multiple compartments so that multiple CCAs could be shielded. Engineering analysis was completed on this specific design to prove that it would reach the necessary engineering design specifications. This preliminary design was created in Solidworks and a thermal analysis was run on it, using the information from the design specifications, like the power output of a generic electrical component. Multiple different material thermal conductivities were analyzed, and the result was a range of thermal conductivities that the material for the enclosure can have to prevent the components of the CCA from overheating. The thermal analysis gave the team a range of material thermal conductivities that would be acceptable to have in the chosen design. The next step is to test the thermal conductivity of metal infused PLAs that the team believes was have a sufficient thermal conductivity.
A financial analysis was completed, which compared the cost of the current manufacturing process compared to the teams proposed process, and also analyzed the return on investment. The result of this analysis was that Raytheon would save $10,000 per enclosure that was engineered and produced. Also, after engineering and producing 7 different enclosures, Raytheon make their money back of they bought an industrial 3D printer specifically for producing CCA enclosures.
The teams most important findings were that, first, none of the metal infused PLA's were electrically conductive, but if they were painted with a nickel conductive coating paint, produced my MG Chemicals and called Super Shield, then the sample was able to prevent electromagnetic interference up to 3 GHz, which is up to our design specifications. For thermal conductivity, it was concluded that the Graphene PLA with the EMI paint was the best solution because it had the highest thermal conductivity value of 0.49 W/m*K. This value did not reach our desired specification of greater than 1 W/m*K, but an enclosure with a thermal conductivity of 0.49 W/m*K still has realistic applications for Raytheon. The applications are just not as broad as they would be with a thermal conductivity greater than 1 W/m*K.
DeFanti, Jared; McWeeney, Michael; and Yekel, Maxwell, "Raytheon Conductive Polymer Printing" (2017). Mechanical Engineering Capstone Design Projects. Paper 24.