Gold is an expensive (non-reactive) metal that improves the performance of connectors in a variety of electrical applications. The benefits of using gold plating include:
1. Excellent corrosion resistance
Gold is very resistant to oxidation or corrosion compared to other metals. Gold plating can act as an effective oxidation and corrosion barrier in situations where a connector's contacts may be exposed to corrosive substances or conditions. Therefore, gold-plated connectors are an excellent choice for applications where the connector or contacts may be exposed to more corrosive conditions.
Applications for gold-plated connectors include high humidity environments or frequent thermal cycling and exposure to corrosive salts or acids. In more demanding applications, heavier gold deposits or even dual-phase gold deposits may be required to ensure that there is enough gold to eliminate any pores in the deposit, creating an effective corrosion barrier.
2. High conductivity
Gold is the third most conductive metal in the world after copper and silver. Gold, however, does not produce any oxides or other compounds, so it retains its high conductivity even at high temperatures or when exposed to corrosive environments. Gold's high consistent conductivity ensures stable current flow even at very low voltages, making gold an excellent choice for electronic applications where millivolts transmit milliamps.
3. Enhanced durability
Electroplated gold can be alloyed with small amounts of nickel or cobalt to increase hardness from pure gold (< 90="" knoop)="" to="" as="" high="" as="" 200="" knoop.="" this="" hardened="" gold="" is="" often="" referred="" to="" as="" hard="" gold.="" when="" plated="" to="" sufficient="" thickness="" (=""> 50uin) on electrolytic or electroless nickel substrates, hard gold provides a durable coating for repeated bonding cycles. Due to its natural lubricity, hard gold is not prone to wear or abrasion.
4. Extensibility
Because gold is a malleable metal, it is suitable for flexible connections and springs. The malleability of gold makes the coating more likely to withstand multiple contact cycles. However, gold-plated electrical connectors or springs require suitable backplane material to ensure that the surface finish meets the design requirements. When electroplating flexible contacts or springs, engineered nickel (eg nickel sulfamate) is often recommended as a gold-plated backplane.
5. Solderable layer
Gold plating is an excellent surface finish for reliable solder joints, requiring only mild rosin flux and consistent and uniform wetting without acid activation. Gold plating is possible on virtually any substrate, including stainless steel terminals or connectors for subsequent connections by soldering. Typically, only a thin soft gold deposit of 0.00001 inches per side is required to form reliable solderable gold contacts, but heavier gold deposits can also be soldered.
When soldered to gold electrodeposited layers, the gold plating diffuses into the solder joint through a mechanism called solid state diffusion. Due to this phenomenon, care should be taken not to exceed 3 percent by weight of gold in the solder joint, as this can lead to embrittlement of the solder joint itself. As a general rule, deposits less than 0.00005" per side will result in less than 3 percent gold by weight in the solder joint
6. Non-magnetic
Finally, gold is not magnetic. This is advantageous where electromagnetic fields can interfere. For example, gold plating may be suitable for connectors used in medical equipment such as magnetic resonance imaging (MRI) scanners.
