Most people never see a galvanic coating. It sits as a layer between 0.1 and 20 microns thick on contacts, pins and components inside products we use every day. But without that layer, the connector in your charging station would generate heat, the circuit board in the wind turbine controller would corrode and the soldering process at the factory would fail.
At Chem-Tec Plating, we have been working with galvanic surface treatment since 1986. In this article, we review what the technology can do, what coatings we offer, and why choosing a metal is rarely as straightforward as it seems.
How a galvanic process works
The principle is classic electrochemistry. The workpiece is immersed in an electrolyte with metal ions, and when current is applied, the ions precipitate as a solid metal layer on the surface. By controlling current, time, temperature and bath chemistry, we can achieve a desired layer thickness with great accuracy.
It sounds simple, and the basic principle is over 180 years old. The hard part lies in all that goes into it: the pre-treatment, the choice of undercoating, the adhesion to your specific base material, and the documentation that the layer actually has the thickness and properties that the drawing requires. This is where experience makes the difference.
Gold: Pure 24 karat or durable hard gold
Gold is the obvious choice where the contact resistance must be low and the connection stable for many years. That's why it's used on contacts, plugs, springs and circuit boards in most professional electronics.
We offer three types. Soft gold and antique gold are pure 24 karat gold, with soft gold primarily used for electronics, while antique gold is lighter in tone and typically chosen for decorative purposes, such as items that are to look like brass. Hard gold is alloyed with approximately 0.2 percent nickel or cobalt to achieve a hardness of around 160 HV, and is the workhorse for contacting. All three are typically applied in thicknesses from 0.1 to 2.5 microns.
Gold is almost always applied on top of an undercoat of nickel, matte or shiny depending on the desired end result. With this build-up we can coat steel, stainless steel, aluminum and tin bronze.
Silver: The best leader in the periodic table
Silver conducts electricity and heat better than gold and is also significantly cheaper. This makes it a strong choice for high voltage applications, where contact resistance must be reduced, and in HF circuits. Silver is also solderable and very ductile, so the coating follows when the workpiece is machined.
Silver tarnishes over time because it reacts with sulfur compounds in the air, but we can postpone this by passivating after the coating. Our silver coatings are mainly for technical purposes and are typically applied in 3 to 20 microns on steel, copper, brass and, with chemical nickel as an intermediate layer, also on aluminum.
Tin: Underrated and indispensable
Tin rarely makes headlines, but it is one of the most widely used functional coatings. It protects against corrosion, has good contact properties and excellent solderability. That is why tin-plated parts are found in electrical cabinets, offshore equipment and wherever soldering is required in production.
We offer tin in both matte and glossy finishes, typically in 5 to 15 microns, often with nickel or copper as an undercoating. Tin can be applied to iron, brass, copper and aluminum, among other materials.
Nickel, chrome and copper: The rest of the palette
In addition to the precious metals and tin, our electroplating program covers nickel plating, pearl nickel, black nickel, anthracite nickel, tin/nickel, chrome plating, black chrome and copper. The nickel variants range from the purely functional to the decorative, where black and anthracite-colored surfaces are in demand for design and instrument applications. Copper is often used as a conductive intermediate layer or to build up thickness before the final coating is applied.
The combination is the point. A finished surface is rarely one metal, but a structure of several layers, where each layer fulfills its task: adhesion, conductivity, corrosion protection, finish.
Reel-to-reel: When items are counted in kilometers
For punched or smooth metal strips, for example for pins, contacts, antennas and springs, it often makes more sense to coat the strip before the parts are punched free. This is called reel-to-reel, and we run it on two lines.
The strength of the method is the selectivity. We can coat partially, that is, from an edge at a controlled depth or in stripes along the strip, and we can coat only one side. Gold only needs to be where the contact actually occurs. This saves precious metal, and at a full production volume, that saving is not to be overlooked.
We coat nickel, tin, gold, silver and copper strips on materials such as steel, stainless steel, tin bronze, copper, brass and nickel silver. Copper, silver and gold are handled in widths up to 80 mm, nickel and tin up to 120 mm. And the scale is flexible in both directions: we can run test strips down to 20 meters when a new item needs to be validated, and produce several kilometers when it goes into operation.
From one topic to many millions
Our processing plant is built to handle series sizes at all levels. A prototype for the development department, an intermediate series for pilot production or million-piece series in a drum. This means that the coating that was validated on the first ten parts is the same as that on part number two million.
And you don't have to make the choice of coating alone. Our specialists advise on which structure best meets the requirements for functionality, durability and appearance, and our own laboratory documents that the result lives up to the promise of the drawing.
The choice of surface treatment is rarely black and white. Send your drawing to info@chemtec.dk or call 75 67 92 92, and we will assess the task and suggest the team structure that best solves it.
EN 
DK 
DE