EMI and RFI Shielding

Electrically conductive paint is made by mixing an electrically conductive pigment into a non-conductive resin binder. The binder holds the paint together and provides the adhesion, while the conductive filler provides the electrical pathway. Electrical charges travel through the conductive fillers making short jumps through the matrix between particles when necessary. This works best when the fillers are highly concentrated and in the shape of flakes or tubes. Spheres are not optimal for conductivity, but can provide a smooth finish and increase conductivity when used in conjunction with flakes.

Beyond morphology, fillers vary primarily in electrical conductivity, corrosion resistance, and price. MG Chemicals offers conductive paints pigmented with branched carbon powder, nickel flake, silver-coated-copper flake, and silver flake. Carbon is the most cost-effective filler and is fine for RFI shielding and grounding applications. Silver provides the highest conductivity and the greatest shielding effectiveness, especially in high frequency EMI shielding applications. Nickel and Silver-Coated Copper both offer good broad range EMI / RFI shielding, with Silver-Coated-Copper excelling at higher frequencies, but not resisting corrosion as well as the other pigments.

Binding systems can vary greatly. They impact the conductivity and shielding effectiveness of the coating, but not as much as the choice of filler does. They do play a larger role, however, in determining the adhesion, durability, and chemical resistance of the coating. They also determine how the coating will be applied; properties like working time and number of components are determined by the binder system. MG offers conductive paints formulated with solvent-based-acyclic, water-based, epoxy, and urethane binding systems.

Applications

    - EMI / RFI Shielding
    - Prototyping and repairing circuits
    - ESD protection
    - Grounding surfaces
    - Galvanic corrosion resistance
    - Electroplating plastics