Electronic devices are everywhere these days – from your cell phone to your garage door opener, to the sensors on the security cameras at the grocery store. They’re controlled by internal circuit boards, which send and receive signals with instructions about what to do (i.e. display the phone’s home screen, send power to the garage door actuator, make the camera record when an object passes).
As devices have become smaller to fit inside machines, vehicles, and medical equipment, they have also become more powerful. Their microprocessors run at higher speeds, and send high-frequency signals between circuits that are very close together.
Where electromagnetic radiation comes from
Electromagnetic (EM) radiation comes from waves of alternating electric and magnetic energy within a device or electronic circuit. The frequency of a wave (i.e. how often a new wave is produced) is inversely related to the size of the wave: higher frequency (i.e. faster signal transmission) equals smaller wavelength.
While they’re in operation, all electronic and communication devices produce waves that fall somewhere in the electromagnetic spectrum. PCBs, communication devices, WiFi signals, and vehicle safety devices use various, sometimes overlapping, subsets of this spectrum. Most devices contain several circuits, each of which gives off and can be adversely affected by neighboring EM signals, so the potential for interference between signals is high in many of the devices we rely on.
Radiation and the interference it causes can also come from radio and cell phone towers, power lines, and even electrical storms.
Interference and its consequences
Like a walkway crowded with pedestrians, if the same frequency range contains too many signals in the same space at once it becomes difficult for any individual signal to pass through intact and reach its destination as intended. Interference essentially clutters the frequency range, resulting in incomplete data transfer, partially blocked signals, data loss, and in the worst cases, device failure.
Electromagnetic and radio frequency interference (EMI and RFI) cause problems because they alter the ability of one circuit to trigger the next action or circuit correctly (or even at all). This is because they interfere with the transmission or reception of data. Examples of devices that can be sensitive to interference and malfunction include:
- Object or location detection systems/sensors. Systems may become unable to detect objects or locations accurately; they may become unable to send detection signals to equipment that triggers a warning (e.g. drifting outside lane lines); they may become unable to notify operators of approaching vehicles or aircraft.
- Navigation systems. With GPS systems, the inability to locate a vehicle or update a route, or to maintain an accurate timestamp; in aircraft, flight path data may be recorded incorrectly or have gaps.
- Wireless door lock systems. Interrupted signals may fail to trigger locking mechanisms.
- Pacemakers and implantable cardioverter defibrillators (ICD). Sensor data may not be sent or may fail to trigger an action in a timely manner, or a device may fail entirely.
- Heart rate and blood pressure monitors. These devices may make inaccurate measurements; fail to capture some data, or fail entirely.
- Ultrasound transducers. These may lose the ability to translate waves into accurate or complete images due to missing or lost data.
- Cockpit radios and aircraft communication devices. Interference can lead to disrupted communication between pilots and air traffic control.
- Connection points on devices. Interference is generated around USB ports, fuse panel insertion points, and press-fit pin slots.
Metal shielding offers protection
Stamped metal shields are a trusted and effective way to reduce the amount of EM radiation circuits emit and the amount that reaches them from outside.
Not all sections of a PCB and not all circuits are typically shielded. Designers are familiar with which circuits emit harmful amounts of radiation and which are most susceptible to interference from radiation. This is what guides strategic shield placement and types of circuits used, including partitioning of critical and non-critical circuits and proximity of analog and digital circuits.
Precision stamping gives you the ability to create parts to your specifications, customized for your application. And if you work with an experienced partner, you’ll have access to knowledge of the details of the manufacturing process, material selection, and efficient production. Please contact us to talk about your stamping needs today.