Plating Precious Metals On Refractory Metals in Electrical Connectors

Electroplating Precious Metals Onto Refractory Metals in Electrical Connectors

There are many uses of electroplating in electrical connectors, from improving corrosion resistance and electrical conductivity1 to increasing strength and longevity. Electroplating processes allow for a more conducive and reliable surface metalto be added to a substrate and enable manufacturers to benefit from the plating metals’ advantages without the cost3 of creating electrical connectors entirely from precious metals.

The consumer electrics market alone generated a revenue of $987 billion4 in 2022, and maintaining the quality of electrical connectors and other components is essential in manufacturing these products. As people become more reliant on their technology every day, they expect quality and longevity in items such as cell phones, computers and smartwatches. Manufacturers must balance growing consumer needs for quality with the cost of mass-producing electrical components, and electroplating precious metals onto refractory metals — those resistant to heat and wear5 — provides the perfect balance between resilience and quality.

Electroplating is one of the most critical processes in manufacturing electronic components. However, the process can be delicate due to the size and complexity of the parts. Working with an electroplating expert6 is the best way to find suitable precious metals for your application and ensure efficient production.

Why Do We Plate Connectors in Electrical Components?

Electrical contact plating is critical in keeping device components functioning correctly over time. Electrical components rely on stable contact materials7, like precious metals, to provide reliability and longevity in performance. Precious metals like gold8 are commonly used in electrical connector applications due to their tarnish resistance and stability in the unique circumstances required by electrical components.

There are several choices regarding the appropriate plating for electrical components. Other noble metals such as silver, palladium and rhodium all have electrical component applications. They are corrosion-resistant and improve conductability9. Factors like environmental humidity, electricity transfer, and wear and tear influence the choice of plating metal10. In some cases, multilayer systems can reduce precious metal usage11.

Regardless, the cost of these materials can be prohibitive. Using refractory metals such as tungsten12 provides a cost-effective base, and electroplating is a popular method for applying precious metal contact finishes in high-volume manufacturing.

In short, plating connectors is essential in manufacturing electrical components, enhancing their performance, reliability and durability in electronic systems. Reliable components lead to satisfied customers and enhanced reputation, which is vital to maintaining a competitive edge in the digital age. Many manufacturers constantly seek the highest quality and most reliable electroplating options to improve their products.

The Benefits of Electroplating for Electronic Contacts and Connectors

Electroplating adds a step — and additional costs — to the manufacturing process. However, the benefits outweigh the costs and labor. Some of the many benefits of electroplating for contacts and connectors include the following:

Improved Corrosion Resistance

Electroplating a layer of metal with strong oxidation resistance onto a base metal can improve contact corrosion resistance13 when exposed to moisture or harsh environments. In applications where rust prevention is vital, noble metals and some passive metals like nickel are plated to enhance the longevity of electrical components.

For example, copper is highly conductive but prone to corrosion14. Using iron or iron alloy as an underplate and plating it with corrosion-resistant options like gold or nickel prevents corrosion without impacting conductivity.

Enhanced Electrical Conductivity

Surface oxides can form on a contact15 or connector, inhibiting its ability to conduct electricity. Contact plating with metals containing anti-oxidation properties can prevent this surface formation16. Many precious metals also offer a smooth finish17 in plating, enabling a solid connection with the mated surface and limiting signal interruptions in electrical components.

Many base metals are strong and resilient for electrical components, as they resist wear and tear. Plating with highly conductive metals shields the base metals from the atmosphere and reduces electrical resistance18, leading to better conductivity and improved performance in electrical components.

Low Contact Resistance

Contact resistance is the resistance at electrical connection points19 that opposes the flow of an electric current. Surface irregularities, such as tiny scratches or rough spots, can form in these connection points due to repeated mating and unmating cycles. Over time, this wear and tear create greater contact resistance, impeding the electric signals.

Electroplating electric contacts and connectors creates a smooth surface finish, significantly reducing contact resistance. The electric signals encounter fewer obstacles as they travel through the components. Again, noble metals with anti-oxidation properties help keep contact surfaces smoother for longer, increasing the longevity of electrical components.

Improved Solderability

Electroplating can enhance solderability in electric components. Metals bond better when easily wetted20 during manufacturing, providing more reliable circuits. Precious metals are often more suited for soldering and welding than base metals, improving manufacturing and producing a more robust end product.

Increased Protection From Wear and Tear

Some electrical components need to perform in harsh environments or mate frequently. Any external forces, such as temperature, humidity, friction and overuse, can impact the performance of electric items21. Electroplating with a metal resistant to such wear and tear22 protects the metal conductor, improves the durability of components, and prolongs the contact life span.

If electrical components are frequently exposed to high temperatures, the heat can damage the contacts23 without the additional protection provided by electroplating. Precious metals such as gold and silver can protect contacts24 from high temperatures.

Enhanced Electroplating Adhesion

Adhesion — the ability of metals to bond25 with one another — is essential in creating reliable and functional electrical components. Electroplating promotes adhesion by enhancing or altering the properties26 of metal parts by placing the substrate in an electrolyte solution. This process improves adhesion, reducing flaking in the plating and protecting the base metal beneath.

Optimized Compatibility

Galvanic corrosion can occur when two metals come into contact27 due to different electrochemical potentials. This corrosion can degrade electrical components and ultimately lead to equipment failure.

Compatability is particularly important in complex electrical systems with multiple moving parts. Electroplating with a compatible noble metal like gold or silver optimizes the compatibility of connectors28 with the surrounding components, limiting galvanic corrosion, providing more reliable electrical connections and prolonging the life span of the parts.

Improved Coating Application

Successful electroplating relies on applying a very thin metal coat onto electrical contacts. If a coating is too thick, it can impede contact performance. Precious metals like gold are highly malleable29, making applying the required thin coating more straightforward. In addition, applying the thinnest layer possible is more cost-effective30, as you use less metal.

Types of Contact Plating for Connectors

There are several different types of contact plating31. Certain metals may be more suitable for specific components and environments depending on the application. Some of the most common types of contact plating include the following:

Nickel Plating

Nickel is a passive metal commonly used in electroplating as it’s suitable for many applications32. It’s hard, durable and corrosion-resistant33 and withstands significant wear and tear. Extreme heat treatment and diamond composites can fortify34 the metal further.

This metal is a perfect option for high-use components35, as it can withstand additional pressure and resist damage from the elements. Its high electrical conductivity and ability to achieve an even coating make it a popular choice. It’s also an economical option36 for improved corrosion resistance.

Gold Plating

Gold is a precious metal and one of the most sought-after choices for electric plating37. It’s incredibly conductive even at low voltages38 and highly resistant to oxidation and corrosion, making it suitable for humid environments and frequent thermal cycling. Gold is tarnish-resistant39, easy to bond and solder, and has low and stable contact resistance40.

It is suitable for many applications and specifically helpful in creating springs and flexible connections41 in electrical components. It’s also non-magnetic, making it ideal for medical applications like magnetic resonance imaging42 (MRI) scanners. Gold is a premium choice43, so one of the drawbacks of using it is the cost. It is expensive compared to other options, but being highly malleable allows users to reduce the amount used in plating.

Silver Plating

Silver offers another highly conductive plating option44 without the additional cost of gold, making this precious metal perfect for larger components. It’s slightly harder than gold and performs well in high-power electricity applications45. Silver is a metallic lubricant ideal for threaded46 or sliding contacts.

This ductile and malleable metal also has antimicrobial properties47, making it suitable for many medical applications. Silver is an excellent plating option for many uses but provides relatively poor corrosion protection48

Tin Plating

Tin is a cost-effective plating option49 with some corrosion resistance, although it can be re-flowed for increased corrosion protection50. This metal is best for applications with relatively low mating cycles and is unsuited for continuous service at high temperatures. 

Tin is an environmental choice, as it is Restriction of Hazardous Substances51 (RoHS) compliant. It has low contact resistance and good solderability, making it an excellent low-cost option52.

Palladium Plating

Palladium is a noble metal53, highly resistant to corrosion. It’s harder than gold or silver, making it extremely durable54 in high-stress environments. It’s common practice to build deposit thickness with palladium and flash a small layer of gold55 for contacts and connectors.

This precious metal is commonly used56 for catalytic converters because it absorbs hydrogen. It has low surface contact resistance and is better suited to applications without acid exposure, as it’s susceptible to certain acids57. It’s also best for applications with relatively low heat, as it has a low melting point58 and limited heat resistance.

Palladium Nickel Plating

This alloy originated as a cost-effective alternative to gold. It’s a robust plating alternative59 suited for applications that require durability and lightweight components60. It’s less sensitive to fluctuations in the plating process and often flashes with gold to add lubricating properties and better corrosion resistance, and it provides a lightweight coating that resists corrosion and cracking.

Palladium nickel has low contact resistance and good solderability. It’s highly durable, withstands many mating cycles and performs well in high-heat environments. However, palladium nickel is better suited to applications where components don’t move against each other, as it has a higher friction coefficient61 than other metals, which can result in fretting — wear at the asperities of contact surfaces.

Rhodium Plating

Rhodium is an extremely hardy plating option62 suitable for applications that require acid resistance. It’s stronger than palladium and has high electrical conductivity63 and impressive corrosion resistance. It also has low and stable contact resistance and is chemically inert64, so it doesn’t react with other metals during electroplating.

This metal is a highly durable option with significant benefits, but its price is subject to considerable fluctuations65, making it expensive to use. At times, rhodium can be more costly than gold or silver.

Copper Plating

Copper has one of the highest electrical conductivity66 rates of any metal. It is highly cost-effective67, malleable and has excellent adhesion properties, making it a perfect electroplating option. However, copper has some properties that result in certain limitations. It’s an active metal prone to corrosion68, so it works best as an underplate or in dry, stable environments.

Platinum Plating

Platinum is a precious metal that offers durability and longevity69. It’s conductive and corrosion-resistant and does not tarnish70, making it an excellent choice for applications that require protection from the elements or extreme heat. It’s highly durable and wear-resistant — you can increase the thickness to add longevity and bulk components. It’s also used as an intermediary layer71 in some applications to allow for better adhesion.

Ruthenium Plating

Ruthenium is commonly used to manufacture data storage products72, such as microchips and read elements for semiconductors. It’s often alloyed with precious metals such as platinum and palladium to harden them for use73 in wear-resistant electrical contacts, as the process enables a thinner coating.

It’s a highly heat-resistant and durable option with a chemically inert surface74. Its long-lasting nature makes ruthenium a popular choice for surface coatings, as it doesn’t wear off or tarnish quickly.

Electroplate Connectors in Electrical Components With SPC

Electroplating is a critical part of manufacturing electrical components. With many plating options for your contacts and connectors, the best choice of materials depends entirely on your budget and manufacturing needs. Improving the quality of your manufacturing processes is essential to ensure you elevate your competitive position in the marketplace.

You can rely on SPC to walk you through75 which electroplating materials and processes best suit your unique requirements. Since 1925, we have developed decades of metal finishing experience. We have a proven track record of plating for electronics and serve organizations across many industries. We’ve also served as consultants for other plating companies. Whether you need to consult on a specific project or overhaul your manufacturing processes, we’re here to help.

We have refined our electroplating processes over the years to improve the quality of your manufacturing processes and help ensure you can pass on that quality to customers. Request a no-obligation quote today76, or contact us for more information on how SPC can help you. You can also subscribe to our free e-newsletter and stay ahead of the latest electronic plating and metal finishing trends.

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