Advanced electronics finds applications in the aerospace industry in segments such as navigation systems, propulsion systems, and more. These electronic systems require good-quality PCB assemblies that fit their requirements not only in terms of complex designs but also electromagnetic compatibility (EMC) and resistance to environmental parameters. To ensure quality and safety, thorough testing is performed in compliance with testing regulations. There are various standards in this regard. RTCA/DO-160D defines the standard environmental test conditions and the relevant EMC test procedures for airborne equipment. This test standard offers the manufacturer a medium to demonstrate the performance characteristics of a given aerospace equipment in the required operating environment. Using EMI shields at the board level helps mitigate EMI and make the device electromagnetically compatible. This post offers an overview of the EMC requirements in the RTCA/DO-160D testing standard and how EMI shields can be helpful in this regard.
RTCA/DO-160D EMC Testing Standards Discussed
The Radio Technical Commission for Aeronautics (RTCA) has published the DO-160 Environmental Conditions and Test Procedures for Airborne Equipment standard for environmental testing of avionics hardware. These tests offer lab-based simulation of the environmental and electrical conditions in aircraft to check the performance characteristics of the airborne equipment. They are done to check the equipment performance in various parameters ranging from temperature, humidity, and vibration to crash safety, sand and dust, and more. Electromagnetic compatibility is one such important parameter, wherein they check if the electronic systems can function in the presence of electromagnetic induction (EMI). The tests are done to ensure that equipment’s electromagnetic emission comply with the regulatory limits. Also, conducted emissions tests are performed to check the conductive interfaces of the equipment and ensure the emissions do not impact the functioning of the sensors. Here are the areas of testing electromagnetic compatibility under different sections of RTCA/DO-160.
- Magnetic effect: Broadcast signals can interfere with nearby electronics operating in similar frequency ranges.
- Power input: These ubiquitous devices emit RF signals that can potentially disrupt sensitive electronics.
- Voltage spike: Wireless headphones or speakers can create low-level RF interference in close proximity.
- Audio frequency conducted susceptibility: This test checks if the device is susceptible to audio frequency conducted susceptibility of power lines.
- Induced signal susceptibility: This test checks induced signal susceptibility, which means if a circuit will accept and withstand induced voltage.
- Radiofrequency susceptibility: In this test, the equipment wiring is exposed to RF-modulated power. These susceptibility tests are conducted in specific power ranges, wherein RF signals are introduced into the power lines through radiated fields. The device is expected to withstand radiated and conducted RF signals and function normally.
- Emission of radio frequency energy: This test is done to check if the equipment RF noise beyond specified levels. The purpose here is to safeguard the operating frequencies of RF sensors.
- Lightning-induced transient susceptibility: This test simulates the lightning effect and defines various components, such as cable bundles, core wires, and calibration loops, in transient susceptibility testing to check tolerance to lightning strokes.
- Lighting direct effects: This test checks if equipment can withstand direct lightning exposure in a real environment, which is essential for aircraft systems and components.
- Electrostatic discharge (ESD): Sometimes, electrostatic exchanges may happen in aircraft due to human contact, low humidity, plastic components, seats, and more such factors. This test checks the ESD immunity of airborne equipment.
Are you a manufacturer in the avionics sector looking to test your equipment for EMC? If yes, you must consider achieving immunity from EMI right at PCB level. While most devices now are designed to be EMC compatible, EMI shielding helps control board-level internal and external noise. Flexible, plasticized EMI shields prevent unwanted signals and subsequent damage to the board and in turn the avionic equipment. These shields conform to the shape of the board, and hence are lightweight and flexible to ensure proper fitment and area coverage. XGR Technologies offers SnapShot™ EMI shields made from a thin polyetherimide film on the interior and conductive tin on the exterior surfaces. These flexible and lightweight shields can be easily used on any type of PCB to mitigate electromagnetic inference in avionic equipment or any devices in high-frequency applications. If you need further information on SnapShotTM EMI shields and their effectiveness in shielding EMI in PCB assemblies used in avionics, you can contact the team at XGR Technologies via phone or email.
