Boedon, Weaving for Sieving & Filtering

EMI Shielding Technology

What Are Common Issues About EMI Shielding?

Boedon EMI shields are built on years of experience, research, and commitment to building and developing an effective EMI/RFI shielding technology. The company provides raw materials to many medical device manufacturing companies and shielding solution design company.

Electromagnetic Interference (EMI) and Radio Frequency Interference (RFI) are two types of electromagnetic interference known to affect electronic devices. Both types of interference reduce electronic signal strength and integrity, which may lead to poor functioning of electronic devices. RFI is a subset of EMI; these terms are used interchangeably. EMI/RFI shielding is done to reduce the impact of EMI/RFI on any electronic circuit. This shielding prevents external and internal electromagnetic waves from interfering with devices or circuits.

Boedon's metal raw materials have been strictly screened and used in a variety of fields that require high precision, such as medical, military, aerospace, etc.

Medical MRI work will have EMI electromagnetic shielding to prevent interference.

Medical

A military drone with EMI shielding is flying in the sky

Military

A person is checking whether the aircraft is equipped with EMI shielding system.

Aerospace

Frequently Asked Questions about EMI RFI Shielding:

Electromagnetic Interference (EMI) refers to the radiation or conducted electromagnetic fields generated by electronic devices. EMI consists of three components: the source, the receiver, and the path. The source is the external phenomenon or circuit that generates the interference; the receiver is the device or signal affected by the interference. Interference propagates along the path through one of four coupling modes: conduction, radiation, capacitive, and magnetic EMI.

EMI is a result of the close relationship between electricity and magnetism. Electric current generates small magnetic fields, and magnetic fields can also affect electric current. Conductors can act as radio antennas. When high-power radio devices and power supplies operate, they generate interference. As devices become increasingly complex, compact, and dense, they become more vulnerable and susceptible to EMI. This interference can be caused by natural phenomena such as auroras, lightning, solar flares, or cosmic microwaves, as well as by circuits involving cellular networks, power transmission lines, AM/FM radio waves, and control devices.

  • Conductive EMI. As the name suggests, it is generated due to the conductive path between the source and the receiver. There are stray currents in this conductive path, which can lead to interference. Conductive EMI is further divided into two types: differential mode and common mode. In differential mode, stray currents flow in opposite directions through the power line, unaffected by the ground; Whereas in common mode, stray currents flow in the same direction between the two systems.
  • Capacitive EMI. This type of EMI occurs between two conductors that are kept at a close distance, sometimes only a wavelength apart. This small distance creates a parasitic capacitance, which becomes a channel for transmitting stray currents.
  • Magnetic EMI. Magnetic EMI operate similarly to capacitive EMI, with the only difference being that it generates current in another conductor through electromagnetic induction.
  • Radiated EMI. This refers to the electromagnetic field formed between the receiver and the source. This electromagnetic interference is transmitted to the circuit through conductors (such as circuit board traces and cables), a phenomenon known as radiated EMI.

EMI and RFI are generated by electronic devices. RFI is a subset of EMI. Generally, these two terms can be used interchangeably. RFI is a type of long-wavelength interference generated by external sources. EMI is a type of short-range interference caused by high-frequency radiation from devices. Both long-range and short-range interference can damage electronic components.

EMI/RFI shielding refers to a commonly used technology aimed at suppressing the effects of EMI/RFI on electronic devices. Designers and engineers can effectively attenuate strong electromagnetic signals before they reach critical electronic devices through effective EMI/RFI shielding. This shielding is typically made from conductive materials to provide effective protection against electromagnetic interference.

The effectiveness of EMI/RFI shielding can be measured by any of the following methods:

  • Open field test. This test is conducted in an open area with no metallic equipment nearby. Antennas placed at varying distances from the device are used to measure conducted emissions and radiated field strength.
  • Shielded enclosure test. This EMI/RFI shielding test is suitable for testing frequencies below 500 MHz. Place the shielding device inside a box with openings and record electromagnetic signals from both outside and inside. Measure the signal ratio of internal and external signals to check the effectiveness of the established shielding.
  • Coaxial transmission line test. This technology helps measure the effectiveness of shielding in planar materials. In this type of test, the test device is kept near the planar material and measures the voltage at various frequencies. In the next stage, the test device is removed and replaced with a load device. The voltage readings are similar to those of the test device. The effectiveness of the shielding is measured by comparing the readings of the load device and the reference device.

Here are several common materials used for manufacturing EMI shielding: aluminum, copper and copper alloy/nickel silver.

The following are several common materials used for manufacturing RFI shielding: copper, aluminum, stainless steel and nickel silver.

We can customize the required metal mesh according to your design plan, or our design and R&D department can design a shielding solution for your experiment.