Compact sputtering system for use directly at the workbench

Sputtering offers a surface finish for components with physical properties such as high strength or low weight. Conventional sputtering systems are large and complex; a compact coating system offers an alternative here.

In industry, components are often made from materials that offer special physical properties such as high strength or low weight. However, these materials are often susceptible to corrosion or other influences, which is why they are additionally protected or enhanced by coatings. Electroplating processes are widely used for this purpose, but involve a high level of technical effort and environmental pollution. Sputtering offers a more efficient alternative and uses purely physical processes: A thin protective or decorative layer is created using a plasma process in a vacuum, which is easy to control, especially for precious metals. However, conventional systems are large and complex. This is why W&L Coating Systems has developed the compact NMS 200 series of coating systems. These table-top units offer a flexible, user-friendly solution for high-quality coatings without material loss - directly on the workbench.

For technical reasons, many products have to be manufactured from materials that have specific physical properties, such as high strength, low weight or good thermal conductivity. Although these materials fulfill their respective technical function, they often have weaknesses in other areas - for example, they are not corrosion-resistant or are sensitive to other influences. "Economic considerations also lead to a preference for inexpensive materials, which then require additional protection or aesthetic enhancement," adds Dr. Clemens Ringpfeil, Director Technology at W&L Coating Systems GmbH. This is where surface finishing comes into play. This mainly takes place using electroplating processes. However, the operation of an electroplating shop involves considerable effort: Numerous chemical baths are required, workers must wear special protective equipment and the disposal of used chemicals is often complicated and cost-intensive. In addition, many of these processes are not flexible enough to coat non-conductive materials, for example. This is precisely where the physical coating process of sputtering comes in. In this process, atoms are released from a solid material, the so-called target, by ion bombardment and transferred to the surface of the product. This creates a uniform layer with a higher density, for example, which achieves a good protective effect even with low layer thicknesses. This material saving is particularly useful for precious metal coatings.

Conventional sputtering systems are usually relatively large and require a complex infrastructure in order to function smoothly. A central component is the coating chamber, which must be equipped with high-quality vacuum pumps to generate the necessary pressure conditions. Considerable heat is also generated during the sputtering process, which cannot be easily dissipated by the vacuum. Special cooling systems, usually in the form of cooling water circuits, are therefore required to regulate the temperature and prevent the system from overheating. High demands are also placed on the sputtering power supply, as it must keep the process stable and ensure uniform layer formation. As a result, conventional systems are often relatively large and not very flexible to handle. For this reason, W&L Coating Systems has developed the compact sputtering systems of the NMS 200 series, which can be operated on a workbench and still enable high-quality coating.

The sputtering systems in the NMS series are designed for economical use of the dispensing material (target). The NMS 250 is ideal for individual parts and small batches that require a high-quality coating. "Operation is extremely simple: it only requires a 230 V connection and an argon supply, such as can be provided by a small gas cylinder," explains Dr. Ringpfeil. The device uses an innovative tube design that serves as a target carrier and vacuum housing at the same time. The magnets that support the sputtering process rotate outside the tube and are cooled by a simple flow of air. The result: a compact coating chamber with a diameter of around 60 mm and a height of 200 mm, which works efficiently and still ensures a high coating quality.

A particular advantage is the homogeneous erosion of the target and the fact that the material that is not deposited on the substrate during the coating process can be returned directly to the target and reused. "Only a minimal amount ends up on the small protective plates on the end faces, which can be easily recycled and the precious metal recovered," says Dr. Ringpfeil. This means that no material is lost, as is often the case with conventional sputtering systems. Changing the target, i.e. replacing the coating materials, can be done in a few simple steps without any additional tools.

The NMS-BM 270 is ideal for even smaller parts that cannot be fixed by a substrate holder, such as roller bearing balls or threaded pins. Using the principle of the NMS 250, i.e. as an air-cooled table-top device with magnets that are exposed to the ambient atmosphere and largely rely on the same peripherals, a horizontal alignment of the target tube was implemented. "Unlike the previous concept, in the NMS-BM 270 the tube rotates and the magnets are fixed relative to it," explains Dr. Ringpfeil. This ensures that the bulk material remains in continuous motion, which guarantees a uniform coating. Depending on the type of parts to be coated, the tube can be filled with a bulk material volume of up to approx. 300 ml.

In addition, the magnetic field can be raised using a lifting mechanism, while a second magnetic field is applied to the target tube from below. This enables sputter etching of the substrates as pre-cleaning before the actual coating, as the plasma is formed directly above the bulk material. "Although this process is not completely residue-free, it proves to be extremely efficient," says Dr. Ringpfeil. In addition, the entire vacuum vessel can be swiveled flexibly - upwards for filling and downwards for emptying. To change the target, the tube is brought into a vertical position. Although tools are required here, the change is usually completed in less than 10 minutes. (OM-4/25)