Electromagnetic interference (EMI) is electrical noise which creates a disturbance or undesired response in circuits, equipment, or systems. EMI is a generalization of an older term, radio-frequency interference (RFI). Many types of electrical circuits are susceptible to EMI/RFI and must be shielded to ensure proper performance.

Shielding is the use of plastic coating to reduce radiated EMI/RFI by reflection and/or absorption. Shielding should be placed where it best causes an abrupt discontinuity in the path of electromagnetic waves. Shielding effectiveness and performance is a function of the properties and configuration of the shielding materials, the frequency and the distance from the source to the shield.