Page 13 - ConnectorSupplier.com 2019 How-to-Specify E-Book

Current-Carrying Capabilities
Electrical connectors are designed to pass electric currents or signals across a separable interface with as few alterations to the original signal as possible. Copper is one of the best conductors for electricity. Therefore, the higher the copper content in a contact material, the more current it can carry relative to its mass. However, copper is expensive. So, pin and socket contacts used to simply transfer a signal can often use materials with a lower copper content, while those used to pass significant electrical current generally require a material with a higher copper content.
A graphical comparison of the current-carrying capacity, machinability, and tensile strength of four common contact materials: brass, phosphor bronze, leaded nickel copper, and beryllium copper.
Cost
Electrical contacts are often one of the costliest aspects of a connector. It is no surprise that stronger metals with higher tensile strength and those with higher current carrying capacities cost more. Similarly, brass alloys are less expensive than leaded nickel copper (e.g., CDA 1915 or C97) and beryllium copper, and phosphor bronze costs more than brass, but less than alloys with a higher copper content.
Availability
The availability of metal materials affects manufacturing in two significant ways. The scarcer a metal, the more difficult it is to source and purchase — even at expectedly higher costs. Some types of copper, specifically C97 (a low-alloy copper) and beryllium copper, can also be difficult to source, which not only increases the cost, but also the lead-times for contact delivery.
In addition to the availability or scarcity of metal, the US Department of Defense (DoD) has strict purchasing regulations for raw materials. Many of these regulations, including those specified in the Defense Federal Acquisition Regulation (DFARS), are designed to ensure that materials do not originate from a single source or from countries with adverse US relations, which definitely has its benefits, but can add to additional material cost fluctuations beyond normal supply and demand.
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