Robust wireless connectivity and high-speed internet have become crucial for various data transfer applications including small- to medium-sized files that can be sent over long distances. 2.4GHz is a frequency band used for network applications in homes and offices. However, it is important for any network and the connected devices to be free from EMI and subsequent damage. The 2.4GHz frequency band is often used as it has a single access point to connect to the internet via a router, and is easy to set up. However, 2.4GHz wireless networks may suffer from electromagnetic interference, thus causing signal disruptions and affecting their performance and reliability. To mitigate the EMI issue in this low-frequency band, using EMI shields right from the board level has proven effective. This post discusses the type of board-level shields (BLS) used for the 2.4GHz band to suppress EMI and safeguard the network and connected devices.
Understanding the Importance of 2.4GHz Shielding
The 802.11 standards govern the 2,4GHz frequency band; however, it is globally available and used for unlicensed communication devices. It is often used in smart home or office IoT devices, Bluetooth, Wi-Fi, ZigBee, and other wireless communication technologies. The devices involved may be digital and analog, such as cordless phones, microwave ovens, refrigerators, and more. These devices feature printed circuit boards (PCBs). Some of the devices may be prone to producing EMI. EMI shielding becomes crucial for the PCBs in this frequency band. Here are some pointers that signify the importance of EMI shielding.
- Electromagnetic interference from the devices in the vicinity may lead to signal degradation and reduced data rates.
- Board-level shielding is important because there are certain EMI-sensitive components mounted on the board, such as RF circuits, microprocessors, memory modules, and more may get damaged. Also, some EMI-producing components may cause disruptions in circuit functioning. This, on the whole, impacts the connected device in which it is embedded and in turn, the network functioning.
- Any unlicensed connected device, if prone to produce EMI, may cause noise disruptions and pose security issues due to signal leakage and unintentional or malicious unauthorized access or interceptions into a network.
- The network, devices, or systems may fail to comply with the required industry regulations, IEEE standards, leading to possible litigations, product recalls, and overall losses.
Role of Board Level Shields (BLS) in 2.4GHz Shielding
Board-level shields effectively curtail internal and external EMI in PCBs. It helps suppress EMI produced by some PCB components from clashing with nearby devices. It offers effective isolation at 2.4GHz frequency band applications. Here’s how PCB EMI shields help noise mitigation in 2.4GHz frequency band applications.
- Physical barrier: Board-level shields create a physical barrier around sensitive components on the board, while maintaining free areas for ventilation and heat dissipation. This cuts out noise in wireless applications such as Wi-Fi and Bluetooth.
- Flexibility: These shields can be cut out based on the PCB design, considering the wiring, vias, and the area where maximum sensitive components are mounted. These flexible shields conform to the shape and size of the PCB.
- Curtail internal and external EMI: These shields pose a direct physical barrier and hence suppress internal EMI from leaking outside and external signals from penetrating into the board components.
- Thermal management: These shields can be designed or customized based on the PCB design and the heat sinks to facilitate proper ventilation and heat dissipation.
- Custom options for 2.4GHz: These super flexible shields can be tailored to target specific components operating at 2.4GHz.
Key Considerations for 2.4GHz Shielding Using Board-Level Shields
Here are some factors you should consider when considering board level shields for 2.4GHz applications.
- Material selection: Choose polyetherimide or polyester which has a conductive coating of copper or tin on one side. So, this must be a plasticized metal multi-cavity shield to accommodate all the required components on the board, while cavities on the shield setting the required areas free for conductive wires, ventilation, and more.
- Size and form factor: The shield must be a thin film with a small form factor. The exact size would depend on the PCB in question. It must be lightweight and flexible.
- Flexibility: It must bend and conform to the shape and size of the board. It must cover the required bents, soldered joints, and more. The material must have the ability to be thermoformed into any design without losing its properties.
- Conductivity: The inner side must be non-conductive and made of polyimide, which helps suppress the internal EMI. The external side should have a conductive tin layer that absorbs the external EMI signals and prevents them from entering the board.
- Grounding: Proper grounding is essential to avoid stray capacitances and grounding loops.
- Ventilation: Thermal management, just like the PCB design, is an essential factor for the shield design as well. The shield cavities must be designed to leave space for heat dissipation to prevent overheating and shorting possibilities.
Applications of Board-Level Shields in 2.4GHz Devices
Here are some application areas:
- Wi-Fi Routers and Access Points: Devices connected to a Wi-Fi network operating at 2.4GHz are prone to interference from nearby or other connected devices. BLS helps minimize internal noise and protects the RF circuits, ensuring stable and reliable connectivity.
- Bluetooth Devices: Bluetooth operates within the 2.4GHz ISM band. PCB shields allow sensitive components on the board to communicate effectively without interference from other wireless signals.
- Wireless Medical Devices: Many medical devices rely on the 2.4GHz band for data transmission. They may operate in environments with multiple wireless signals. In such cases, board level shields help prevent EMI and establish connectivity and communication among devices.
- IoT Devices: The Internet of Things (IoT) uses the 2.4GHz band extensively, which includes many smart home and smart office devices. BLS helps IoT devices maintain stable communication in densely populated areas with multiple overlapping signals.
Effective shielding is necessary at the PCB level, especially for components operating at the 2.4GHz frequency band. This is because of the complexities arising from densely mounted components and complex designs, and small form factors. EMI suppression is crucial for the normal functioning of the circuit and in turn the device. The best way to shield board-level EMI is by using plasticized EMI shields with an inner conductive side. XGR Technologies offers SnapShot EMI shields made from a thin polyetherimide film on the interior and conductive tin on the exterior surfaces. These flexible, lightweight shields help reduce electromagnetic inference and are applicable for 2.4GHz frequency band components. If you need further information on these EMI shields, you can contact the team at XGR Technologies via phone or email.
