How to Protect a Circuit Board with PCB RF Shield

When manufacturing a circuit board, one needs to also pay attention to the protection. If a circuit board functions optimally, in terms of the wiring, but it doesn’t have the right security measures, it will only be a matter of time before it develops issues.

This is the reason why the PCB RF shield was developed to address the problem. In this blog post, you will find out what it is all about.

What Does PCB RF Shield Mean?

Also called PCB Shielding or EMC/EMI Shielding, it is a mechanized method of improving the protective capabilities of a circuit board.

The concept of Electromagnetic Compatibility (EMC) Shielding implies the protection of a Printed Circuit Board (PCB) against the external Electromagnetic signals. This protection is offered as a way of keeping the circuit board’s signals in active shape, while making sure that the internal signals do not escape and in the process, disrupt the nearby devices.

A clear example of how the PCB RF shield works is when you have a radio working and a telephone ring beside it. The shrieking noise it makes signifies the interruption of the workings of the radio’s internal workings.

EMC vs. EMI Shielding

Although the two are often written together, they have some similarities. While the former stands for Electromagnetic Compatibility (EMC), the latter stands for Electromagnetic Interference (EMI).

It is the duty of the EMC to use or delegate a metallic screen that absorbs the Electromagnetic Interference (EMI). This absorption helps the EMC to shield the PCB from the EMI traveling through or being transmitted through the air. This way, the interference wouldn’t disrupt the circuit board’s performance.

The Relevance of RF Shielding for PCBs

Circuit boards, including different electronic devices, are susceptible to disruptions from different sources. When it comes to the impact these disruptions have on the circuit board’s performance, it is enormous.

For example, the board becomes vulnerable to Electromagnetic Interferences (EMIs), one of which is the Radio Frequency Interference (RFI).

In that case, you wouldn’t expect the expected output from the board, as it has been negatively impacted by the unwanted signal/interference.

It is for this reason that using the PCB RF shield to protect the board from unwanted signals emitted via Radio Frequency (RF) is important.

In terms of the RF shielding’s relevance, it has to do with the absorption or reflection of the Electromagnetic Interference (EMI) radiations. Any of those ensures that the circuit boards or electronic devices are not susceptible to the Radio Frequency Interference (RFI).

The Types of PCB RF Shields

There are two (2) major types of shields used to protect Printed Circuit Boards (PCBs) against Radio Frequency Interference (RFI).

The two are explained below:

1. PCB RF Shielding

This is the primary shielding process that works by lowering the following:

  • Radio waves
  • Electrostatic
  • Electromagnetic fields

The lowering of the above goes a long way to block both the Radio Frequencies (RF) and the Electromagnetic radiations from having a negative impact on the board.

The design of the PCB RF Shielding includes enclosures of metal that provide an all-around enclosure or covering of the sensitive circuit inside.

It is worthy of mention that the covering of the circuit is enhanced by the blockage of the electrostatic fields using the “Faraday Cage.”

The Role of the “Faraday Cage”

The “Faraday Cage,” used to block off the electrostatic fields, is a form of metallic screen that completely surrounds either the transmitting electronics or the sensitive electronics.

Furthermore, the metallic screen takes in (absorbs) the transmitted signals and goes on to release a current within the screen’s body.

The released current, would then be absorbed by either the virtual ground plane or the ground connection on the board.

2. Arduino Shielding

You can use Arduino Shielding if you don’t prefer to go with the PCB RF Shielding. This one works by providing a surface-mount process for protecting or shielding the circuit board.

The design is that the shield pins would be inserted into the sockets located below both sides of the Arduino circuit board.

When this is done, it will allow for the mounting of the Arduino EMC PCB Shield atop the Arduino circuit board.

Electromagnetic Interference (EMI): Types and Sources

There are two main types and three sources of Electromagnetic Interference (EMI). The types are broadband EMI and narrowband EMI, while the sources are industrial, natural and residential.

For the types, the following are the important pieces of information you need to know:

  • Broadband EMI: this type of Electromagnetic Interference (EMI) is tenable over Radio Frequencies (RF), as well as via lamps, circuits, lightning and power lines.
  • Narrowband EMI: this type of EMI is generated via the following: cellphones, radios, and television sets.

The differences between the narrowband and broadband EMI are based on the number of frequencies and the extent of the damage. For the frequencies, the narrowband EMI often occurs within either a single frequency or a narrow band of frequencies, while the broadband EMI occurs over Radio Frequencies (RFs).

The broadband EMI can cause interference with the electronics at home and make damages leading to data loss in industrial settings. This is unlike the limited damage (mixing up of signals) tenable with the narrowband EMI.

The following are the sources of Electromagnetic Interference (EMI) for Printed Circuit Boards (PCBs):

  • Industrial: Electromagnetic Interference (EMI) emanating through this source causes serious interferences with the PCB’s performance. The industrial sources of EMI include but are not limited to power grids, cellular networks, radios, satellites and railroads.
  • Natural Sources: these include the atmosphere electricity, snowstorms, cosmic noise, the sun and lightning strikes.
  • Residential EMI: these interferences emanate from the home. Some of the sources are toaster ovens, Wi-Fi devices, microwaves, and Bluetooth devices.

Final Thoughts

The interruptions caused by Electromagnetic Interference (EMI), if not properly managed, would impact the performance of the Printed Circuit Board (PCB).

By using any of the PCB RF shield options (including Arduino Shielding and Faraday Cage), you would be able to protect the device, while positioning the circuit for maximum performance.

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