Electromagnetic shielding materials you don't know

Electromagnetic shielding is to prevent the interference of high-voltage field strength to the components. The design principle of electromagnetic shielding is to use the shield to minimize the distributed capacitance between the interference source and the susceptor, thereby reducing the influence of the interference source on the susceptor.

Electromagnetic shielding materials are various materials that are used between the heat source and the radiator. By removing the air between the heat source and the radiator, the heat distribution of the electronic equipment is more uniform and the heat dissipation efficiency is accelerated. Generally, various thermal interface materials need to have good thermal conductivity and surface wettability.

Electromagnetic shielding materials mainly include the following aspects:

1)Conductive glue

A type of adhesive with conductive properties. Conductive adhesive is an adhesive with certain conductive properties after curing or drying. It usually uses matrix resin and conductive fillers, namely conductive particles, as the main components, and is bonded by matrix resin The function combines the conductive particles together to form a conductive path to realize the conductive connection of the adhered material.


Since the basic resin of the conductive adhesive is an adhesive, you can choose a suitable curing temperature for bonding. At the same time, due to the rapid development of the miniaturization and miniaturization of electronic components and the high density and high integration of printed circuit boards, Conductive glue can be made into the slurry to achieve high line resolution. Moreover, the conductive adhesive has a simple process, easy operation, and can improve production efficiency. Therefore, the conductive adhesive is an ideal choice to replace lead-tin soldering and realize the conductive connection.

2)Electromagnetic shielding series materials

Electromagnetic shielding materials mainly include conductive foam, conductive cloth, conductive double-sided tape, copper foil tape, aluminum foil tape, etc. Let's understand the purpose of these series:

❶ Conductive foam

Conductive foam is mainly divided into ordinary conductive foam and all-round conductive foam. It is made of elastic PU foam covered with textile fiber cloth containing metal coating, which has good elasticity and conductivity and is widely used in EMI prevention and control of various electronic products.

Purpose: It is suitable for occasions that can not provide large pressure, and plays a good electromagnetic sealing effect. Such as electronic shielding cases, notebook computers, mobile communication equipment, plasma displays, etc.


❷ Conductive cloth

The conductive cloth is mainly divided into lattice cloth type conductive cloth and knitted conductive cloth. The lattice cloth has good conductivity, good shielding effect, and good processability. It is suitable for wrapping into various regular and irregular ordinary conductive foam materials. It is mainly suitable for ultra-thin shielding, conductive cloth foam, conductive cloth tape, Conductive cloth liner, etc., and has good anti-friction performance. Knitted conductive cloth has good anti-friction properties, it is easy to be stamped and formed after wrapping, and its low cost and easy wrapping formability make it the material of choice for I/O pads.


Conductive cloth: Since the conductive cloth is a highly metalized nylon or polyester material base material, it has excellent conductivity equivalent to that of metal, and has good toughness and wind ability. It is shielded by various electronic appliances and communication equipment after backing conductive glue. Ideal material, and also very suitable for shielding and grounding of circuit boards or various surfaces.

The main categories of lattice type conductive cloth:
Fabric type: Check cloth;
Metal plating: nickel/copper;
Conductivity: <0.05 ohm/square;
Advantages: easy to shape, strong shear resistance, friction resistance;


Features of grid type conductive cloth:

1. Good conductivity, surface resistance is lower than <0.07 ohm/square.
2. Good shielding effect, shielding effectiveness can reach more than 60dB.
3. Good processability, soft texture, cut without burrs, and easy to overmold.
4. Suitable for wrapping into various regular and irregular conductive foam materials.
5. Mainly used in ultra-thin shielding, conductive cloth foam, conductive cloth tape, conductive cloth liner.
6. Good anti-friction performance, anti-friction times can reach 500,000 times (ASTM-D4966);

The main categories of knitted conductive cloth:

Fabric type: knitted conductive fabric;
Metal plating: nickel/copper;
Conductivity: <0.07 ohm/square;
Advantages: low cost, suitable for I/O foam wrapping;


Features of knitted conductive cloth:

1. Good anti-friction performance, anti-friction times can reach 400,000 times (ASTM-D4966).
2. Low-cost, easy-to-wrap and moldability make it the first choice for I/O gaskets.
3. It is easy to be stamped and formed after wrapping.

❸ Copper foil, aluminum foil conductive tape

A material that is directly rolled into thin sheets of metal copper and aluminum. The general content of electronic products is more than 99%. The material is soft, has good ductility, and has silvery white or golden yellow luster. However, it is easy to oxidize and the color becomes dark, and it will change color when rubbed and touched, so good protection measures must be taken during processing.


Copper foil and aluminum foil are mainly used in the electronic industry for copper strips to conduct electricity, heat conduction, heat dissipation, magnetic shielding, and antistatic. The hardness of the material is not high, usually below 0.2mm, which is very convenient for processing and easy to deform.

Application of copper foil and aluminum foil:

It is mainly used to eliminate electromagnetic interference EMI and isolate the harm of electromagnetic waves to the human body. It is mainly used in manufacturers of computer peripheral wires, computer monitors and transformers.

The use of copper foil and aluminum foil: suitable for all kinds of transformers, mobile phones, computers, PDAs, PDPs, LCD monitors, notebook computers, copiers and other electronic products where electromagnetic shielding is required.

❹All-round conductive foam

Omni-directional conductive foam: It is mainly composed of a foam and conductive cloth wrapped around the foam. The foam is equipped with metal materials that have been vacuum electroplated. It has low cost, good three-dimensional shielding effect and can play Excellent protection performance like metal.


Features: Good shielding effect, good electrical conductivity, high friction resistance, flame retardant and thermal conductivity.
Purpose: Adapt to the shielding of various computers, TVs, notebooks, card readers and other products.

The applications of electromagnetic shielding materials

Electromagnetic shielding materials are used in communication equipment, network terminals, data transmission, LEDs, automobiles, electronics, consumer electronics, medical equipment.

Publication Date: 12 September, 2020

Category: Electromagnetic Material

Tags: EMC

Authors: Konlida

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