Addressing RF Leakage with Effective Board Level Shielding

Radio frequency waves clash against each other in a circuit with cluttered wiring and components, and this results in RFI radio frequency interference. This is similar to yet different than EMI or electromagnetic interference, and must be avoided at all costs as it directly impacts the functioning of the device. RF leakage refers to the unintentional transmission or reception of RF signals outside the circuit paths and from inside board components or outside devices. This leads to interference, signal losses or degradation, and potential security risks. RF leaks may happen due to loose connectors, cables, cracked or damaged equipment, and so on. To mitigate RF leakage, effective board level shielding is crucial. This post discusses ways to address RF leakage and subsequent issues with the help of efficient and effective PCB EMI shields.

Methods for Detecting RF Leakage

1. 1. Spectrum Analyzers
      • Function: Measure the frequency spectrum of RF signals.
      • Use: Identify unintended emissions outside the designated frequency bands.
   2. Near-Field Probes
      • Function: Detect electromagnetic fields near electronic components.
      • Use: Localize sources of leakage on circuit boards.
   3. Network Analyzers
      • Function: Assess the performance of RF networks.
      • Use: Identify mismatches and discontinuities causing leakage.
   4. Thermal Imaging
      • Function: Detect heat generated by excessive RF emission.
      • Use: Visualize areas of leakage due to component heating.
   5. RF Leakage Detectors
      • Function: Portable devices specifically designed for detecting RF leaks.
      • Use: Quickly scan environments for RF emissions.

 

Understanding RF Leakage and its Consequences

Here are some pointers that reflect on the details of RF leakage causes and consequences.

1. • To understand RF leakage, one needs to analyze the flow of low- and high-frequency signals through a circuit, and also understand components, their characteristics, temperature resistance, and other tolerances.
   • One also needs to analyze the capacitance and inductance of wires to estimate RF leakage.
   • Also, it is important to note that RF signals are uncertain and may not follow their conduction paths, especially in compact spaces such as PCBs, wherein there is little space because of traces and wires.
   • This causes capacitive coupling as the capacitors present in empty spaces on boards block low-frequency signals. These capacitors can sense and emit electromagnetic waves or radiation, which gives rise to radiated or inductive coupling.
   • When these signals get into unintended spaces in the board, it causes RF leakage. It happens due to mixing of signals as well as there are both transmitters and receivers in the board.
   • Some other factors for RFI include inadequate shielding design, poor shield-to-shield coupling, gaps or openings in the shield, improper grounding, or inadequate shielding material selection.
   • This degrades signal quality, limit range, and coverage, and even cause potential data breaches through unauthorized access.

 

Design Considerations for Effective Board Level Shielding

To address RF leakage effectively, flawless PCB layout and design are crucial factors. Here are some pointers.

• The implementation of board level shields must be considered at design stage.
• Testing of boards aside from design, development, and manufacturing is a crucial aspect and must be done at each stage.
• During the development and manufacturing process, RF leakage testing and validation should be performed to ensure the effectiveness of board level shielding. These tests include near-field scanning, RF spectrum analysis, and radiated emissions measurements. This helps identify potential leakage points and evaluate the shielding performance.
• The position, shape, size, shape, and material selection of the shield must be decided to achieve optimal shielding effectiveness.
• Grounding techniques, accurate sealing, and minimizing gaps or openings are just as important factors to maintain the shielding integrity.
• The shield material must preferably be a plasticized metal with a non-conductive inner surface and a conductive outer surface.
• These shields have multiple cavities that facilitate heat dissipation.
• Also, they must be designed to be lightweight and flexible, yet robust and resistant to harsh environments.

 

Why Board Level Shielding is Important in RF Containment

Board level shields play a significant role in containing RF signal interference by preventing their entry or escape from a given location. The shields are designed to block or attenuate RF energy, reducing the potential for RF leakage and its associated problems. Shielding effectiveness depends on various factors such as shield material, thickness, conductivity, and the shield's overall design. Some industry segments such as IoT, telecom, GPS devices, medical imaging devices, avionics, military, wireless gadgets, network devices, and so on are prone to RFI. Hence, businesses in these sectors prefer custom shields that offer correct fitment and effectiveness against RFI. These shields when cut out to fit the size and shape of the board considering the holes and vias are the best solution for RFI suppression.

While it is important to prevent RF leakage by ensuring the quality and condition of cables, connectors, connected devices, and so on. RFI can be effectively mitigated through EF shields on PCBs. These shields made of plasticized metal control EMI and RFI, and thus help prevent data leakage and device malfunctioning. It also increases security, efficiency, and operating life of the board and subsequently that of the device. To get reliable and customized EFI shields, ensure you source them from an experienced player in this segment. XGR Technologies offers SnapShot™ EMI shields that are EMC enabled, lightweight, and flexible shields made from plasticized metals. They are made from a thin polyetherimide film on the interior and tin on the exterior surfaces. If you require further information on these EMI shields, you can contact the XGR Technologies team via phone or email.