Electrical contacts are those crucial electrical circuit components for controlling the flow of electricity. Typically found in circuit breakers, switches and relays, contacts are made of electrically conductive metal. When two contacts touch, the circuit closes. Conversely, when the contacts are separated by an insulating gap, it interrupts — or opens — the circuit.
In many applications, the contacts are composed of metals such as nickel, cadmium, copper or various alloys. Plating the contacts with a thin layer of gold can provide an important finishing touch that provides a variety of valuable benefits.
Why Plate Electrical Contacts With Gold?
Gold is an expensive material that increases the cost of the manufacturing process, so why it is so frequently used to plate electrical contacts? Gold contains numerous unique properties that can enhance the finish and improve the quality of the workpiece. Many manufacturers discover that the additional cost of gold plating is offset by the benefits derived, resulting in a solid long-term return on investment.
Plating contacts with gold provides:
- Exceptional corrosion protection: Gold is among the metals that are least susceptible to oxidation. This occurs when iron — or an alloy containing iron — combines with oxygen and moisture and ultimately produces corrosion. Therefore, gold plating electrical contacts can offer a viable solution for applications where rust prevention is essential.
- Increased electrical conductivity: The formation of surface oxides can also inhibit the contact’s ability to conduct electricity. Gold’s anti-oxidation properties prevent this from occurring. They also produce a smooth finish that enables a solid connection with the mated surface.
- Ease of coating application: When electroplating any metal onto electrical contacts, it is imperative that only a very thin coating is applied. Thick coatings will negatively impact contact performance. Gold is one of the most malleable metals, making it easy to apply a very thin coating onto the surface. The fact that only a thin layer of gold is required also helps to minimize the cost.
- Enhanced durability: Gold provides excellent resistance against normal wear and tear, which can lengthen the contacts’ lifespan.
- Excellent heat protection: For electrical products routinely exposed to elevated temperatures, gold provides superior protection against damage causes by excessive heat.
- No fretting degradation: Gold is not susceptible to fretting, which is the gradual wearing away of the contact surface due to rubbing or friction.
When electroplating gold onto electrical contacts, the best practice is to first apply a nickel undercoating to promote adhesion. It is also critical to ensure the coating thickness is appropriate for the specific application.