A shield works through three primary mechanisms: Reflection: The conductive surface reflects incoming electromagnetic waves, like a mirror reflects light. Absorption: Energy from the waves is absorbed and dissipated as heat within the shield material. Multiple Internal Reflection: Any remaining energy is attenuated by reflecting inside the shield. Effective shielding requires a continuous conductive path and proper grounding to channel intercepted energy away.

Material choice depends on frequency, mechanical needs, and environment. Metals: Copper and aluminum are excellent for high-frequency shielding. Pre-tinned copper or beryllium copper is often used for gaskets/spring fingers due to corrosion resistance and durability. Steel provides good magnetic shielding at lower frequencies. Conductive Elastomers: Silicone or rubber loaded with conductive particles (like silver, nickel, or graphite) create flexible, environmental seals that also shield. Specific compounds (e.g., 40-60-0505-1298) are engineered for optimal conductivity and compression. Specialty Materials: Conductive fabrics, tapes, coatings, and advanced composites like graphene are used for specific applications. The "best" material balances shielding effectiveness, cost, form factor, and environmental sealing needs.

Use shielded cables where the inner conductors are surrounded by a conductive braid or foil. This shield must be properly grounded at one or both ends (depending on application). For added protection or to bundle unshielded wires, use EMI shielding sleeves or wraps. EMI shielding tape is also effective for wrapping connectors or sealing seams.

Yes, in almost all cases. Grounding provides a safe, low-impedance path for intercepted interference currents to drain to earth/ground plane. An ungrounded shield is far less effective and can act as an antenna, worsening the problem. This applies to cable shields, enclosure panels, and conductive gaskets.

Shielding Effectiveness (SE) is measured in decibels (dB). It quantifies how much the shield reduces the field strength. Testing is done in specialized chambers (anechoic or TEM cells) using signal generators and sensitive receivers. SE is calculated as: SE (dB) = 10 log10 (Power without shield / Power with shield). Higher dB values indicate better shielding.

Installation: For board-level shields (BLS), they are soldered via Surface Mount Technology (SMT). Gaskets require even compression. Tape must be applied to clean, continuous surfaces. The key is ensuring 360-degree contact with no gaps. Removal: Device shields (e.g., in phones/routers) are often soldered or clipped in. Removal requires careful disassembly, often using specialized tools and heat. Removing a shield may void warranties and should only be done by qualified personnel.