Electronics for extreme environments
Usually mounted to the engine fan case, engine control units ensure safe and optimal engine operation regardless of the high temperatures it faces. However, migrating them to the engine core would bring a host of advantages. These relate to reduced system complexity and weight, simplified assembly as well as maintenance and nacelle aerodynamic improvement. Typical operating temperatures at the engine core are much higher compared to those found in the fan case. In such an environment, today’s electronic control units would exhibit inferior performance, reduced reliability and extremely short lifetime. The EU-funded project HITME (High temperature electronics) laid the groundwork for developing a safety-critical electronic control system able to withstand engine temperatures above 300 degrees Celsius. Enhancing state-of-the art electronic components was a key objective. The focus was on components based on high-temperature silicon-on-insulator processes that expand the operating range of conventional silicon processing for use in harsh environments. In addition, scientists looked at components based on silicon carbide that can operate at temperatures above 300 degrees Celsius for prolonged duration. Increased use of electronics in harsh environments as well as rising densities and power of electronic components require suitable thermal management solutions. The project proposed active cooling solutions and insulation approaches for the semiconductor material (die), the metallic case (package) and the substrate. In addition, researchers examined the possibility to use smart electronics to protect more sensitive components and reduce internal heat generation. Another central activity to reach the project goal was to develop cutting-edge materials for packaging and interconnects. The performance of hitherto used materials based on metals or ceramics is not well known at temperatures above 250 degrees Celsius. Scientists found that non-conductive adhesives are more reliable than conductive ones. In addition, adhesives based on cyanate ester demonstrated better thermal storage properties compared to epoxy compounds. HITME successfully developed two demonstrator vehicles to test the concepts developed throughout the project lifetime. The first one was used to evaluate circuit functions at high temperatures, while the second one assessed the integrity, mounting and interconnection of a small autonomous line replaceable unit.
Keywords
Extreme environments, engine control units, high-temperature electronics, silicon-on-insulator, thermal management
