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There are many factors to consider when undertaking the design and manufacture of electronic systems for an aerospace application. The harsh end-use environments, stringent safety standards, high-quality levels, and tightly controlled component traceability required can render more conventional approaches insufficient.
Recently, Corintech Ltd. completed an emergency lighting system for a mainstream aircraft. As the purpose of the device was to warn the pilot of any issues present within the aircraft, reliability was of the highest priority. The team at Corintech worked closely with the client to design and manufacture an LED array using Thick Film Hybrid technology, a long-term area of expertise for the company.
Thick Film Hybrid circuits are produced using an additive manufacturing process as opposed to the subtractive process normally implemented to produce FR4 PCBs, whereby a complete layer of copper is chemically etched to reveal the finished circuit. Thick Film Hybrids typically use a ceramic substrate onto which precious and semi-precious metal pastes are printed and then fired at high temperatures to cure. The use of different pastes allows the production of conductive tracks as well as resistors, which can be custom specified and then laser-trimmed to a high level of accuracy, offering exact choice of value so that no compromise in design is necessary.
Ceramic substrates provide a number of key advantages over standard FR4 based PCBs. One of the primary advantages is their thermal conductivity. Corintech uses Aluminium Oxide (Alumina), which offers an increase in thermal conductivity of approximately 30 times that of FR4, and Aluminium Nitride, which offers an increase of approximately 200 times. This often negates the need for additional heat-sink design and cooling components, as the ceramic substrate dissipates heat evenly across its entire surface.
Another advantage of ceramic substrates is that they offer extremely low thermal expansion properties. This makes them ideal for use in harsh environments where extremes of temperature are likely. The combination of low thermal expansion and high thermal conductivity ensures that not only is thermal expansion limited, but it is also evenly spread across the board, limiting large amounts of stress to be exerted in specific areas.
Corintech has specialised in the design and production of Thick Film Hybrids for over 40-years. They are able to manufacture multi-layer ceramic circuits including printed tracks and resistors, laser trim printed resistors to high tolerances, provide SMT and through-hole assembly on ceramic and FR4 PCBs, and place bare die components with wire bonding.
In addition to the materials and technology used in aerospace builds, it is vital that any supplying sub-contractor adhere to the relevant quality standards, in this case, AS9100. The AS9100 aerospace and defence quality standard demands an additional 80 requirements and 18 amplifications on top of ISO 9001, meaning builds are manufactured and rigorously tested to ensure both reliability and durability. The attainment of the AS9100 accreditation is the mark that an electronics manufacturer has a tightly controlled quality management system at each stage in its process. One of the elements of the AS9100 requirements is that all components must be sourced from the correct supply chain and that the traceability is tracked throughout to ensure high levels of reliability and quality across every element of the build.
At Corintech, the AS9100 not only benefits aerospace and defence builds but all designs and assemblies. Their expert procurement team operates across a global network of sourcing options and long term relationships with trusted supplies, making sure that every component is fully traceable and purchased for the lowest price possible to keep BOM costs low. This, alongside stringent IPG610 quality inspection standard as well as builds passing through our state-of-the-art automated optical inspection machinery, assures of the upmost quality from beginning to end.
To find out more about Corintech or their aerospace experience, contact them today.