Page 17 - 2021 Connectivity Components: Everything but the Connectors eBook

Selective Plating is Worth its Weight in Gold
Steve Smashey, President, and Mike Conte, General Manager, SOS Engineering Inc.
High-quality electrical contacts are the core of any high-performance connector. Electrical contacts play a vital role in the integrity and reliability of signal transmissions, especially in harsh environment and mission-critical applications. Robust contacts utilize high-quality materials and terminations to meet rugged application requirements. Gold plating is a key part of the ruggedization process that ensures physical and electrical performance specifications are met. However, gold plating is the most expensive aspect of the connector design. Selective gold plating enables connector manufacturers to achieve the required level of robustness for harsh environments while limiting the use of costly gold on contacts.
Metal plating
Metal plating is used to enhance the physical or electrical performance of components. The type of plating material used directly correlates to the performance characteristics of a connector contact. Materials are chosen for several performance characteristics, including corrosion resistance, electrical conductivity, thermal conductivity, solderability, wear resistance, operational life, and infrared (IR) reflectivity. Metals commonly used for plating include silver, copper, nickel, tin, and gold.
Higher quality materials inherently produce higher quality contacts. Brass alloy is typically sourced for electrical contacts used in commercial applications. For harsh environments and mission-critical applications, copper alloys are commonly used for their high resistance to corrosion. Leaded nickel copper or beryllium copper are ideal for their tensile strength and durability. To meet additional performance specifications, contacts are often electroplated after manufacturing.
Harsh environment and mission-critical applications require the highest level of protection from severe environmental conditions. Metals like nickel or copper react poorly to moisture and humidity, so gold is often used in demanding applications because of its natural resistance to oxidation. Gold improves contact durability via enhanced abrasion, temperature, and general corrosion resistance. Gold also improves electrical performance, reduces contact resistance, and enhances solderability, conductibility, and shielding. As one of the most highly conductive metals, gold offers significantly less signal loss and better data rates than other options.
17