Today’s advanced electronic gadgets have compact-sized yet multilayered printed circuit boards (PCBs) with several sensitive components mounted on them. This makes them susceptible to electromagnetic interference (EMI) and radio frequency interference (RFI), and hence it is essential for PCB design engineers to include shielding techniques. This helps mitigate or suppress EMI or RF signals coming from various components or the external environment. PCB shields are effective in controlling EMI and RFI, and hence must be considered in the layout in terms of size, shape, thickness, holes and vias, ventilation, and more. Also, it is essential for designers to comply with industry standards to ensure the board is electromagnetically compatible. There is a huge demand for EMC-enabled boards. This post discusses the significance of using EMI shields and how they help elevate the PCB design in terms of achieving EMC.
Ways to Control RFI and Improve Board Design
Electromagnetic and radio frequency waves can come from external as well as internal sources, and both need to be mitigated. There are various ways to control RFI including using good-quality board-level EMI shields.
- High-frequency signals are a prerequisite in today’s complex electronic applications, and this gives rise to RFI emanating from high-speed signals, switching components, transceivers, and so on. This may percolate at the board level and damage the functioning of the final device or system. By using the right type of EMI shields, board-level RFI can be prevented because of the physical barrier created.
- While appropriate grounding is a common method for controlling EMI from external sources, ground plane for EMI shields offers a conducting area or an enclosure where all the RF signals and other signals that contribute to noise simply enter and exit the plane. It creates a low impedance path for all such signals to find the ground reference point and dissipate. Ground planes can eliminate any currents coming from stray fields and are mostly connected to a single point power supply.
- At times, especially in high-frequency applications, the type of holes for ventilation may offer venue for the RF signals to radiate to the external environment. This may also impact the functioning of the device. Hence, while ventilation of components and heat sinks are crucial aspects, the slots or holes in the enclosure must be of a certain dimensions and shape to control the radiation of RF signals.
- Proper spacing is an important part of PCB design, and it is best to avoid parallel analog traces to prevent noise and crosstalk. This is because oscillating waves induce noise in traces that run parallel and carry signals in the same direction. However, in today’s small-sized boards there may not be enough space to prevent parallel traces as a lot needs to be fitted in a confined area. Here, a grounded trace can be included as part of design to shield crosstalk.
- The ground planes must be away from the antenna as this can induce noise from external sources which the antenna senses. This may damage the sensitive components. To avoid this, via holes can be planned in such a way that they segregate the antenna and the ground plane.
- All these points among many others can be considered when designing the PCB layout to control EMI and RFI. Aside from this, the use of EMI shields which are conductive on one side and non-conductive on the other may serve the purpose. Look for a plasticized metal that offers the required flexibility to be cut to the exact dimensions of the board. Also, ensure they are removable for any work that needs to be done on the board in the future. Ensure these shields are lightweight so that they do not add any extra weight to the board and in turn the device.
Effective PCB shields not only suppress EMI but also help protect data leakages as they shield the signals from crossing their area. Efficient board level shielding solutions are crucial to the overall product or system as they facilitate effective functioning. Hence, it is essential to use reliable shields made by reputed and certified manufacturers. This process requires a detailed analysis of requirements in terms of PCB dimensions, shape, holes, vias, wiring, component placement, and overall, the complete design and layout. After this, the right shielding materials are selected. If shielding is included in the design process, the shields can be cut out to suit the exact board requirements, thus enhancing the overall accuracy and efficiency of the circuit. This leaves no loopholes such as uncovered wires or components, covering heat sinks, and more. If you are an electronics manufacturer, you will need PCB shields that not only mitigate EMI but also fit into compact spaces on small boards. XGR Technologies offers SnapShot® EMI shields that are lightweight, flexible, and offer isolation for a wide frequency range from below 1 GHz to 12 GHz. They are made of plasticized metal, which offers both bendability and structural stability. These can be customized to suit specific requirements. You can contact the XGR Technologies team today if you are interested in knowing more about these EMI shields or sharing your requirements.
