Impact of Spacecraft Vibration on Printed Circuit Board Assemblies
Managing Vibrations in Space Vehicle Printed Circuit Boards
Space vehicles are subjected to a unique and challenging vibration environment, which can have detrimental effects on their Printed Circuit Board Assemblies (PCBAs). Understanding the sources of these vibrations and the impact they have on PCBAs is crucial for ensuring the reliability and performance of electronic systems in space.
Sources of Vibrations in Space Vehicles
Vibrations in space vehicles originate from various sources, including mechanical vibrations and operational harmonics, launch-induced vibrations, acoustic vibrations and shock, vibrations from fluid systems, and thermal cycling and radiation effects.
Mechanical vibrations stem from rotating or reciprocating components such as engines, turbines, gears, and propellers. Launch-induced vibrations are caused by engine thrust oscillations, aerodynamic forces, and structural resonances during liftoff. Acoustic vibrations and shock are induced by high sound pressure levels during liftoff, while vibrations from fluid systems result from propellant flow and pumping systems. Thermal cycling and radiation effects, although not direct vibration sources, interact with vibration stresses in space electronics.
Effects of Vibrations on PCBAs
The harsh vibration environment in space vehicles can lead to several issues in PCBAs. Mechanical fatigue and solder joint failure, component loosening or damage, signal integrity degradation, and flex PCB advantages are some of the key effects. Repeated vibrational stresses can cause micro-cracking or fracture in solder joints, potentially leading to electrical open circuits. Vibration can also cause components or connectors to loosen, degrade, or delaminate from the PCB substrate. Additionally, vibration-induced mechanical strain can impact high-frequency and sensitive signal paths, affecting reliability and performance, especially in avionics and spacecraft applications.
Mitigating Vibrations in PCBAs
To combat the effects of vibrations on PCBAs, several strategies can be employed. Utilizing flexible printed circuit boards (Flex PCBs) is one such strategy, as they are better at absorbing and withstanding intense vibration, shock, and thermal cycling, reducing solder joint failures and improving reliability compared to traditional rigid PCBs.
Proper soldering techniques are also essential for establishing reliable connections on the PCB. Sealing agents used in component assembly act as shock absorbers and help reduce vibrations on the board. Critical nets need to be routed on the same layer or a minimum via should be used along with a second redundant track and via to prevent open circuit failures of a single interconnection.
Additionally, conductors should have wide dimensions to avoid slivers and be peelable, and thermal control measures such as radiators, thermal blankets, surface coatings, and heaters are used to maintain thermal balance in space vehicles. De-rating, or operating devices or components below their normal operating range, is another strategy for minimizing failure rates in severe working conditions.
In conclusion, managing vibrations in space vehicle PCBAs is a critical aspect of ensuring the reliability and performance of electronic systems in space. By understanding the sources of vibrations, employing strategies such as Flex PCBs, proper soldering techniques, and thermal control measures, and implementing vibration testing standards like NASA’s Dynamics Stand, we can mitigate the effects of vibrations and improve the durability of electronics in the harsh space environment.
[1] NASA Dynamics Stand [2] Understanding Vibration Effects on PCBAs in Space Applications [3] Vibration Analysis and Control in Spacecraft Systems [4] IPC Class 3 Design Guide [5] Effect of Launch-Induced Vibrations on Spacecraft Systems
Scientists often leverage technology in the form of a material selector to design and manufacture flexible printed circuit boards (Flex PCBs), which are better equipped to withstand the harsh vibration environment encountered in space vehicles, reducing the likelihood of solder joint failures and improving overall reliability.
Understanding medical-conditions analogous to those affecting electronic systems in the space environment, such as mechanical fatigue and solder joint failure, can provide valuable insights into the impact of vibrations on Printed Circuit Board Assemblies (PCBAs) and guide the development of effective strategies to mitigate these effects.
