Circuit board shielding materials and techniques play a major role in reducing or eliminating radio frequency (RF) or electromagnetic (EM) interference. EMI is nothing but disrupting electromagnetic energy emanated by a single section of an electrical circuit that reaches the other areas of the same circuit. The disruptive energy can also reach the external environment through radiated or conducted paths. EM or RF interference affects the performance of a device circuit, and if significantly high, may harm brain cells as well as other human organs. Therefore, the objective of board level shielding materials is to minimize radiation levels for optimal device functioning, health, and safety.
EMI Originates from Two Sources
With our increasing dependence on wireless devices and communications, interference is a common problem, and it radiates from two primary sources. The first one is the RF front-end that passes the unwanted signal and the second source is the internal circuits of electronic devices operating at higher clock rates and gigahertz. That’s why you require a perfectly designed circuit board with the least emitted interference to operate at the best speed and meet all performance requirements. Whether you manufacture personal computers, smartphones, tablets, or any other devices, you need a printed circuit board (PCB) design with effective EMI shielding.
Effectiveness of PCB Design and Shielding
The main goal of the PCB design and shielding process is to protect the critical portions of the board to eliminate or reduce harmful emissions or prevent interference from other sections of the circuit from interfering with sensitive circuits. Besides metal shields that protect important circuits, additional materials such as gaskets are used to reduce interference.
Varieties of Shield Materials Used
EMI shields come in different sizes and shapes and may vary from simple metal boxes to films and conductive foams. You can collaborate with EMI shielding suppliers to design custom shapes based on your specific requirements.
How Shielding Works
EMI shielding materials create a positive obstruction to enclose sensitive circuits, thus providing isolation and preventing radiations from leaking out. Though a shielding material should ideally be a sealed conductive enclosure without any gaps or openings, the use of such a material is not feasible because the inside of a container has inputs and outputs requiring ground and power connections. And, if proper precautions are not taken, there will be leakage-related issues. Shielding can become an economical solution when used together with other suppression methods like filtering, grounding, and professional PCB design and shielding.
EMI/RFI Shielding Capacity
The capacity of the shielding material to reduce or eliminate unwanted radiations depends on a host of factors like material permeability, conductivity, and thickness. Moreover, the material’s ability to reflect the emissions is often controlled by both conductivity and permeability. While designing circuit board shields, engineers must factor in problems like mechanical strength, air circulation, and other aspects. Many EMI shielding products integrate holes or apertures in the design to allow the flow of air. This is beneficial in reducing heat buildup in sections of the circuit that absorb considerable power.
Choice of Gasket Materials
You can choose from a wide range of gaskets depending on quality, materials, and geometry. Opt for varieties like beryllium copper, knitted wire mesh, metal spring fingers, conductive fabric-over-foam, and particle-filled elastomer products. These gasket materials come with their respective benefits and drawbacks based on the kind of application. Irrespective of the type of gasket you choose, the important aspects to keep in mind while choosing them are shielding efficiency, RF impedance, compression range, compressibility, environmental sealing, and compression set.
Choose circuit board shielding materials that provide maximum EMI control, and are designed based on mandatory specifications, compliance guidelines, and environmental issues. They are custom designed to eliminate harmful emissions and are ideal for business and government bodies with specific requirements. Contact a reliable shielding solutions provider to choose the correct product.