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Contact surfaces with less gold

Contact Surfaces in Connectors - High Performance Is Possible Even with Less Gold

State-of-the-art electroplating processes improve the cost-effectiveness of PCB connectors

When the absolute reliability of a connector must be guaranteed over the long term even under demanding operating and environmental conditions, gold-plated contact surfaces remain the first choice for connectors. In many applications, however, performance requirements can also be met using a plating system that requires a lower gold content.
The design of printed circuit board connectors is typically based on the best possible balance between technical and economic requirements. From a technical standpoint, factors such as the mechanical strength of the connection, the specific operating conditions, and the exact transmission performance requirements must be taken into account. From an economic perspective, the question arises as to how high the product’s quality truly needs to be, given the purpose and duration of the application.

Gold is often the first choice for contact surfaces in connectors.

Especially when it comes to high-quality and technically sophisticated products, customers often automatically specify gold-plated contact surfaces for connectors. In fact, gold is the only material that optimally combines all the properties that define the quality of a connector: Gold is corrosion-resistant and withstands even the harshest environmental conditions, shows virtually no material fatigue even after numerous mating cycles, and ensures optimal transmission of current and voltage even at temperatures up to 150 degrees Celsius. As a more cost-effective alternative, a silver coating is traditionally used—and, depending on the application, may even outperform gold in terms of electrical conductivity. However, the significantly higher normal contact force resulting from this can lead to undesirable limitations in the design of the connector in specific cases.

Selective use of gold reduces costs in connector assemblies

Punktuell beschichtete Kontakte Zero8
Fig. 1: Spot coating in a double-sided contact system
Those who do not want to do without gold can at least keep its use to a minimum—for example, by plating the contacts on blade and spring strips only in specific spots, directly at the point where current and voltage are actually transferred.

The Scale-X double-sided contact system of the Zero8 connector uses two spot masks for this purpose, since the functional surfaces are located on both sides.

Learn more about the Scale-X contact system »

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Alternative connector coatings with high functionality

Materialbeschichtungen UEbersichtstabelle
Fig. 2: Contact surfaces used in ept
Palladium-nickel alloy with gold flash

One typical example of an alternative to gold is coating contact surfaces with a combination of 80 percent palladium and 20 percent nickel, topped with a thin layer of gold. This layer is referred to as gold flash. This coating structure offers corrosion resistance comparable to that of gold. The gold flash is necessary to ensure that plug-compatible connectors can be mated with one another without restriction. Additionally, the contact normal force does not need to be adjusted when the coating system is changed. In terms of the key properties of a connector (contact resistance, dielectric strength, current-carrying capacity, self-heating during operation), PdNi contact surfaces ultimately represent a high-performance and cost-effective alternative to products with a pure gold coating.

Nickel-phosphorus alloy with gold flash

Another alternative coating to gold is a nickel-phosphorus alloy to which a thin gold flash layer is additionally applied. The nickel-phosphorus alloy is particularly hard and ductile and is considered chemically noble, as evidenced by its low wear characteristics and high corrosion resistance. Due to the almost complete absence of precious metals, this alloy is very cost-effective.

In-house electroplating at the connector manufacturer offers maximum flexibility

Bandgalvanik IMG 8834
Fig. 3: ept Augsburg Strip Electroplating
Many different electroplating techniques have been used in Europe since the 18th century. The predominant method is single-part electroplating, which is further divided into rack and barrel electroplating. As the name suggests, in rack electroplating, the components to be coated are suspended on racks and immersed. In barrel plating, the individual parts are placed in a barrel and thus immersed in the electrolyte. Barrel plating is typically used for bulk goods such as the board lock in connectors.

When coating connectors, manufacturers often rely on the strip plating process. In this process, components are pulled through a plating line as a continuous strip. Compared to barrel or rack plating, strip plating always maintains consistent process conditions, ensuring a reliable, uniform coating thickness.

In the continuous electroplating manufacturing process, stamped strips containing the contact blanks are automatically fed through the electroplating baths at a relatively high speed. Wound onto spools and thus protected from damage during handling or transport, the coated contacts are then immediately available for automated assembly into connector housings.
Through continuous optimization of the production process, an in-house strip plating facility not only allows for a high degree of flexibility regarding the types of contacts to be processed; it also enables the cost-effective production of contact surfaces tailored to specific requirements. When it comes to the use of gold, a connector manufacturer with its own in-house electroplating facility can reduce the use of this valuable precious metal to an absolute minimum—for example, by plating the contacts of blade and spring terminals only at specific points and directly at the location of the actual current and voltage transfer. Furthermore, having an in-house electroplating facility offers connector manufacturers the advantage of being able to produce a wide variety of other material combinations, such as nickel, tin, tin/lead, nickel/phosphorus, and palladium.
To achieve an optimal cost-benefit ratio and ensure maximum flexibility regarding the contact surface and the coatings to be configured, it is advisable to choose a connector manufacturer with its own electroplating facility. As a family-owned, German quality provider and one of the world’s leading manufacturers of PCB connectors, ept GmbH operates six in-house continuous-flow electroplating lines at two German locations, delivering complete solutions from a single source with high vertical integration, reliability and precision. This infrastructure enables the production of coatings from up to 10 different surface combinations with minimal modification effort.

Quality assurance in our own laboratories

 The customer- and application-specific configuration of PCB connectors is not limited to the surface, but encompasses the entire structure of a contact, including the base material and the intermediate layer. Based on the respective technical and economic requirements, specially developed processes enable the manufacture of highly customized products, whose quality is verified through ongoing testing in our own laboratories. Thus, operation in accordance with specifications is tested under conditions that far exceed the relevant standards. One example is the requirements of DIN 41612 connectors, according to which the quality of a product must be fully guaranteed even after 500 (quality level 1) or 400 (quality level 2) mating cycles. 

A sustainable production process

Made In Europe Siegel v1
In addition to optimal cost-effectiveness and the highest product quality, coating on in-house electroplating lines also allows for the most careful use of resources. In addition to the coating materials, this includes, in particular, the chemical substances required for the electroplating process, which are comprehensively treated at connector manufacturer ept via an internal wastewater treatment system. Furthermore, the rinse water used to clean the electroplated contacts is recirculated through an ion-exchange system, which reduces the systems’ fresh water requirements to a minimum.

ept ensures the sustainability of its production through a comprehensive system of project and process management, as well as its own capabilities for the development and production of all necessary equipment. The company designs the tools and machines required for the manufacture of PCB connectors using its own staff. From custom manufacturing and equipment maintenance to electrical planning, all work necessary for ongoing operations is performed in-house to continuously improve production and adapt it to the latest findings.

Webinar: "Contact Surfaces in the Connector Industry"

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Would you like to learn more about contact surfaces in connector applications and electroplating processes?

Our surface expert, Christoph Schnatz, will explain the key properties of contact surfaces made of gold, silver, nickel, palladium, and tin, and help you determine which contact surface is the right choice in each situation to ensure that factors such as durability, challenging environmental conditions, and electrical conditions do not affect data transmission.

The webinar will provide detailed explanations and practical examples.

More information about the webinar »
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