Electronic Design - Shielding methods in high-speed PCB design

Shielding methods in high-speed PCB design

PCB factory: The transmission rate of the wiring system is accelerating, but it also brings some vulnerabilities to anti-interference. This is because the higher the frequency of information transmission, the more sensitive the signal, and the weaker the signal energy, the more susceptible the wiring system is to interference.

Interference is everywhere.

Cables and equipment may interfere with other components or be severely interfered by other sources of interference, such as computer screens, mobile phones, motors, radio relays, data transmission, and power cables. In addition, potential eavesdroppers, cybercrime, and hackers are also increasing because they may cause significant damage and loss to UTP cable information transmission interception.

Especially when using a high-speed data network, the time required to intercept a large amount of information is significantly less than the time required to intercept low-speed data transmission.

The twisted pair in the data twisted pair can resist external interference and its own twisted pair crosstalk at low frequencies, but at high frequencies (especially when the frequency exceeds 250MHz) the single pair cannot achieve the purpose of anti-interference and can only be shielded To resist external interference.

The cable shield serves as a Faraday shield. The interference signal enters the shielding layer, but does not enter the conductor.

Therefore, data transfer can run without any problems. Shielded cables emit less radiation than unshielded cables, preventing network transmission from being intercepted.

Shielded networks (shielded cables and shielding elements) can significantly reduce the level of electromagnetic radiation that can be intercepted in the surrounding environment.

For different interference fields, there are two options for shielding: electromagnetic interference and radio frequency interference. Electromagnetic interference (EMI) is mainly low-frequency interference.

Motors, fluorescent lights, and wires are common sources of electromagnetic interference. Radio frequency interference (RFI) refers to radio frequency interference, mainly high frequency interference.

Wireless communications such as radio, television broadcasting, and radar are common sources of radio frequency interference.

In terms of anti-electromagnetic interference, braided shielding is the most effective due to its low critical resistance; for radio frequency interference, foil shielding is the most effective, because braided shielding depends on changes in wavelength, and the gap created by braided shielding allows high-frequency signals to pass through. For low-frequency mixed interference fields, the foil layer should be used in combination with a woven network for broadband coverage.

Protection mode.

Generally speaking, the higher the grid shielding coverage, the better the shielding effect.

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