Silver

Silver plating is particularly beneficial in high-frequency applications, where its superior conductivity helps to reduce signal loss and distortion. Silver also has good thermal conductivity, which aids in heat dissipation — a valuable property for components that may heat up due to high-power signals.

One particular advantage of silver is its performance regarding Passive Intermodulation (PIM). PIM is a form of signal interference that can occur in RF systems, typically caused by non-linearities in the system's components. Silver, with its exceptional conductivity and low non-linearity, exhibits excellent PIM performance, making silver-plated connectors a preferred choice for systems where low PIM is a requirement.

However, silver does have some drawbacks. It is prone to tarnish, a form of corrosion that occurs when silver reacts with sulphur compounds in the air to form silver sulphide. This tarnishing can increase contact resistance over time and degrade the component's performance. To mitigate this, silver-plated connectors are often used in combination with a layer of gold plating over the silver. This enhances the corrosion resistance while still benefiting from the superior conductivity of the silver underneath.

Comparatively, gold and tri-metal (typically copper, nickel, and a thin layer of gold) platings offer a better balance of conductivity and corrosion resistance, but they don't match silver's performance in terms of electrical conductivity. Gold is more expensive, while tri-metal, despite being cost-effective and durable, doesn't offer the same high-frequency performance as silver.