Since 2018, there have been at least 100 launches into space orbit. This year, several well-known people ventured into space, including William Shatner, who played the charismatic captain of the Enterprise on the original Star Trek series. This transcendental TV series and the movies it spawned deserve some credit for rekindling the exploratory human spirit.
The new frontier, although exciting, is wrought with hazards not often encountered on earth. These include space radiation—from solar flares, the Van Allen belt and galactic cosmic rays—that can wreak havoc on printed circuit boards. Radiation hardening offers the most common method for mitigating these threats by shielding components, packages and entire boards. A similar protective approach is common for PCBAs where significant disruptive noise or interference is possible. Therefore, a consideration of EMI shielding materials and methods should be included in your design.
When Is EMI Shielding Necessary?
For critical applications such as aerospace systems, the need for shielding to protect sensitive components and circuitry from erroneous behavior or even damage is fairly obvious. However, EMI can pose a problem on nearly all circuit boards where RF devices exist. For example, these devices may be designed as intentional radiators for communications systems; or, they may be unintentional radiators such as digital switching components. If your board contains components that process or create signals that operate in the 9 kHz to 3 GHz range, the potential for producing EMI that may negatively impact reliable operation and performance is likely present, and shielding may be necessary.
Medical devices, especially minimally invasive and invasive systems, also warrant EMI and EMC consideration. Here, the risks are primarily associated with the patient’s safety as unintended electrical discharges may damage internal organs. However, measurement accuracy and precision are also critical, as misdiagnoses can lead to incorrect or unneeded treatment regimens that may adversely impact patients.
Most industrial production facilities today are automated and rely on power electronics that typically utilize higher voltages and/or currents than many commercial products. Often, these electronics are embedded within the equipment, making them a potential source of electromagnetic emission and susceptible to environmental EMI from nearby systems. Designing boards that can operate reliably in potential EMI environments without disrupting the operations of nearby systems, or being excessively susceptible to outside EMI, is known as achieving electromagnetic compatibility (EMC) and often requires EMI shielding.
EMI Shielding PCB Method Considerations
Good PCBA design necessitates the inclusion of onboard EMI or environmental EMC considerations. Following the guidelines listed below can assist you in achieving this objective.
Guidelines for PCB EMI Shielding
There are several methods of EMI shielding that may be deployed on your board:
- Shielding gaskets
- Metal strips
5 Common Mistakes for High-Speed Board Builds
All EMI shielding materials contain reflective metal to prevent emissivity (EMI escaping) and susceptibility (EMI entering) of the protected component, area or board. In many cases, the shielding material(s) are shaped to encompass a specified coverage area. Common materials are:
- Particle-filled Silicone
Depending on your board’s components, operation and intended environment, one of the above EMI shielding materials and methods should be instituted to protect signal integrity. Failing to do so can have significant consequences, ranging from erratic and unpredictable measurements to system failure and even patient harm.
|Tempo's Custom PCB Manufacturing Service
At Tempo Automation, the industry leader for fast, high-quality prototyping and on-demand production, we are experienced in building boards for hazardous environments, including the extremes of space. We can ensure your design intent is integrated throughout the board build and that whatever EMI protection you require is incorporated.
And to help you get started on the best path, we furnish information for your DFM checks and enable you to easily view and download DRC files. If you’re an Altium Designer or Cadence Allegro user, you can simply add these files to your PCB design software. For Mentor Pads or other design packages, we furnish DRC information in other CAD formats and Excel.