Cleaning and pretreatment. Cleaning before PVD [(plasma vapor deposition)] coating

In sanitary areas differently shaped work pieces made from different materials, such as metal and plastic, are treated. Before a PVD coating is applied the component parts must be carefully cleaned such that the hard material layer to be deposited can adhere reliably and uniformly to all work pieces. The use of PVD to coat a hard material for surface upgrading also in mass production places new demands on process and machine engineering with respect to substrate cleaning and PVD deposition. Apart from decorative PVD coatings in other areas, such as in clocks, jewelry, and glasses, the requirements for cleanliness of the surface cover a large and diverse range of products. These products are also made in a variety of materials, mainly brass alloys but also plastics. Most products have narrow borings and blind holes. The PVD deposition occurs in vacuum and the cleanliness of the substrate has an essential influence on the value of the coating especially on the adhesion. Improperly cleaned inner hole spaces can lead to outgassing during the PVD coating and produce a defective coating, wasting an entire charge. Before the PVD coating is applied the substrate is cleaned by ultrasound in mass production facilities. The cleaning process is a multi-step process followed by rinsing steps and drying. This entire process is described along with vacuum drying and improvement of system cost effectiveness.