Electromagnetic shielding materials you might not know about

Electromagnetic shielding is designed to prevent high-voltage field strength interference on components. The principle is to use shielding to minimize the distributed capacitance between the interference source and the base, thereby reducing the interference's impact.

Thermal shielding materials are used between heat sources and heat sinks to eliminate air gaps, ensuring even heat distribution and enhancing heat dissipation efficiency. These thermal conductive interface materials must possess good thermal conductivity and surface wettability.

Electromagnetic shielding materials mainly include the following:

1. Conductive Adhesive

Conductive adhesive is an adhesive with conductive properties after curing or drying. It typically consists of a matrix resin and conductive fillers, such as conductive particles. The bonding effect of the matrix resin combines these particles to form a conductive path, facilitating the conductive connection of the bonded material.

The basic resin of conductive adhesive is a type of adhesive, allowing for the selection of suitable curing temperatures for bonding. With the rapid miniaturization and high-density integration of electronic components and printed circuit boards, conductive adhesive can be formulated into a paste, achieving high line resolution. Additionally, the conductive adhesive process is simple, easy to operate, and enhances production efficiency. Consequently, conductive adhesive is an ideal alternative to lead-tin soldering for achieving conductive connections.

Electromagnetic Shielding Materials
These materials primarily include conductive foam, conductive cloth, conductive double-sided tape, copper foil tape, and aluminum foil tape. Below is an overview of each:

1) Conductive Foam

Conductive foam comes in two types: regular and all-around. It consists of elastic PU foam coated with metal-coated textile fiber cloth, offering elasticity, conductivity, and effective EMI control in electronic products.

Usage: It's ideal for applications needing electromagnetic sealing without high pressure, such as electronic shielding cases, laptops, mobile devices, and plasma displays.

2) Conductive Cloth

Conductive fabrics are primarily categorized into grid-type and knitted conductive fabrics. Grid-type cloth offers excellent conductivity, shielding, and processability, making it suitable for wrapping various regular and irregular conductive foam materials. It is ideal for ultra-thin shielding, conductive cloth foam, conductive cloth tape, and conductive cloth cushions, with good friction resistance. Knitted conductive fabric also provides good friction resistance, is easily stamped and formed after wrapping, and is cost-effective, making it the preferred material for I/O pads.

Conductive cloth, made from metallized nylon or polyester substrate, offers excellent conductivity comparable to metal. It combines good toughness and winding performance, making it ideal for shielding electronic and communication equipment when backed with conductive adhesive. It is also effective for shielding and grounding circuit boards and other surfaces.

Grid-type conductive cloth categories include:

● Fabric type: checkered fabric

● Metal coating: nickel/copper

● Conductivity: <0.05 ohms per square meter

● Advantages: Easy to shape, high shear and friction resistance

Characteristics of grid-type conductive cloth:

1. Excellent conductivity, surface resistance below <0.07 ohms/square.

2. Effective shielding with over 60dB shielding efficiency.

3. Easy to process, soft texture, burr-free cutting, and easily wrapped and shaped.

4. Suitable for wrapping various regular and irregular conductive foam materials.

5. Primarily used for ultra-thin shielding, conductive cloth foam, conductive cloth tape, and padding.

6. High anti-friction performance, enduring up to 500,000 friction cycles (ASTM-D4966).

Main categories of knitted conductive fabrics include:

● Fabric type: knitted conductive fabric

● Metal coating: nickel/copper

● Conductivity: <0.07 ohms/square meter

● Advantages: Cost-effective, ideal for I/O foam wrapping

Characteristics of knitted conductive fabric:

● Excellent anti-friction performance, enduring up to 400,000 friction cycles (ASTM-D4966).

● Cost-effective and easy to wrap, making it ideal for I/O pads.

● Easily stamped and shaped after wrapping.

3） Copper foil and aluminum foil conductive tape

Copper foil and aluminum foil conductive tape are thin sheet materials made by rolling metal copper and aluminum, typically with a purity exceeding 99%. They are commonly used in electronic products for their softness, ductility, and silver-white or gold-yellow luster. However, they are prone to oxidation and color darkening from friction and handling, necessitating careful protective measures during processing.

Copper foil and aluminum foil are primarily used in the electronics industry for conductivity, thermal conductivity, heat dissipation, magnetic shielding, anti-static properties, and other applications. The material is soft, typically less than 0.2mm thick, making it convenient for processing and prone to deformation.

Application of copper foil and aluminum foil:

Mainly used to eliminate electromagnetic interference (EMI) and isolate the harm of electromagnetic waves to the human body, it is mainly used in computer peripheral wires, computer displays, and transformer manufacturers.

The use of copper foil and aluminum foil: suitable for various electronic products such as transformers, mobile phones, computers, PDAs, PDPs, LCD displays, laptops, copiers, etc. that require electromagnetic shielding.

4）Omni-Directional Conductive Foam

Omni-directional conductive foam consists of foam wrapped with conductive cloth, featuring a metal material vacuum-electroplated throughout its body. This design offers cost-effectiveness, a strong three-dimensional shielding effect, and provides excellent protective performance similar to metal.

Features: Excellent shielding effect, high conductivity, superior friction resistance, flame retardant, and thermal conductivity. 

Usage: Ideal for shielding applications in products such as computers, televisions, laptops, and card readers.

Applications of electromagnetic shielding materials:

Electromagnetic shielding materials are applied in communication equipment, network terminals, data transmission, LEDs, automotive, electronics, consumer electronics, and medical devices.