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RF Cans Improve Electromagnetic Compatability in PCBs

Published Date
Author Cadence PCB Solutions

Key Takeaways

  • An RF can is a type of RF shield designed to block electromagnetic or radio-frequency interference. 

  • An RF can encloses the critical circuit section without altering the electrical connection of the respective section with the rest of the circuit board. 

  • RF cans are characterized by the type, length, width, height, ventilation, and mounting techniques. 

 RF can

RF cans are a cost-effective solution that can prevent unwanted RF radiation

Sometimes, sources of RF interference are placed adjacently to each other on a PCB. In such scenarios, PCB designers can place an RF can next to each source of interference to prevent RF radiations from affecting the performance and functionality of critical electronic items.

RF cans are electromagnetic interference (EMI) shielding covers used to shield parts of electronic circuits from EMI or RFI. RF cans are a cost-effective solution that can prevent unwanted RF radiation.

In this article, we will discuss the consequences of RF interference and the importance of using a shielding technique like an RF can. 

The Consequences of RF Interference in a PCB

It is impossible to completely eliminate all issues associated with RF interference in electronic circuits. RF sources can be internal or external. Regardless of the type of source, RF interference disturbs circuit operations and can lead to signal corruption, control glitches, bit errors, or a complete malfunction of the circuit.

Electronic circuits laid on a single PCB may handle different frequencies. If there is a radio communication system that utilizes the radio spectrum in a useful way, other electronic circuits in its vicinity become highly susceptible to RF interference and can be regarded as victims. The negative impact created by unwanted RF radiations on adjacent electronic circuits is harmful and needs to be addressed. 

RF Shielding

There are several methods designers use to mitigate the effects of RF interference on a PCB, including:

  1. Allowing proper spacing between electronic circuits and systems utilizing the RF spectrum.

  2. Sticking to proper circuit designs without compromising.

  3. Incorporating RF shielding techniques. 

In compact and miniaturized circuit design, providing clearance and adhering to all design guidelines are not cost-effective methods. RF shields are the most practical solution to deal with RF interference on a PCB board.

RF shields attenuate the strength of RF interference and diminish the field intensity of RF radiations. RF shields form a barrier between the RF source and the victim, thereby weakening the impact of the interference.

RF shielding is the standard method to mitigate the effects of RF interference on adjacent circuits in a single PCB. RF shields are effective in controlling the emissions from RF sources reaching sensitive targets and can screen the critical circuit or components from unwanted RF radiations as well. 

RF Cans 

RF cans are a type of RF shield designed to block electromagnetic or radio-frequency interference. RF cans are framed as metal covers. The enclosures formed by RF cans reduce the electric and magnetic transmissions from the source to other sensitive electronic components.

RF cans aid the proper functioning of the critical parts of a PCB without being affected by RF disturbances. Along with shielding, RF cans are useful in isolating sensitive parts of a circuit. For example, RF cans are employed for isolating power circuits and control circuits in an electronic device. RF can isolation is particularly important when you have ESD-sensitive components in a circuit. RF cans can also prevent ESD damages caused by accidental finger touches. 

Fixing RF Cans in a PCB 

Fixing RF cans on a PCB does not require any circuit modification; RF cans enclose the critical circuit section without altering the electrical connection of the respective section to the rest of the circuit board. 

RF Can Material and Dimensions

RF cans are characterized by type, length, width, height, ventilation, and mounting techniques. The type of material used for an RF can depends on whether the can is enclosing the source or victim. To enclose the RF source, RF can material should absorb the radiation (e.g., stainless steel). For victim enclosure, RF can material needs to reflect the interference (e.g., aluminum).

When choosing the dimensions of an RF can, it is important to have enough clearance between the tallest component inside and the can top. For ventilation and optimum heat removal from the enclosed circuit, apertures or slots should be cut into RF cans. The mounting types usually found in RF cans are adhesive, snap-on, solder, surface mount, and through-hole. RF cans in PCBs are electrically connected to the ground plane to transfer the current generated in the can metal due to RF interference.

RF cans are essential when you are designing a PCB  requiring high electromagnetic compliance. If you are trying to design an electronic circuit with enclosures, Cadence’s design and analysis software can help you. Cadence’s software offers a full suite of tools to design electromagnetically compatible electronic circuit boards with EMI enclosures.

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