Requirements for Electroplating Technology

Electroplating Technology Requirements Previous assessments have clearly demonstrated that there is scarcely any industrial sector that can function without using electroplated parts. Such parts are required in architecture, the textile and furniture industries, mechanical engineering, aircraft manufacturing, aviation, the electrical and electronics industries. These parts are increasingly used in precision engineering and medical technology, among others. Their use has become routine in optical devices and household appliances, as well as in the sports and camping industries and likewise in the fashion industry. For this reason, it is impossible to ignore the fact that electroplating, like virtually every branch of industry, has found its place not only in the technical field but also in our daily lives to varying degrees. This ubiquitous presence inevitably carries with it the danger that the real conditions of what is demanded from electroplating technology are not always taken into account.

Quality and Productivity

Designers and engineers, in terms of quality and related economic considerations, make demands on coatings produced by electroplating that can fundamentally be summarized as follows: • The lowest possible and homogeneous layer thickness, • Smooth surface, • Compact and fine-grained structure, • High corrosion resistance, • Freedom from internal stresses, • Sufficient ductility, • High hardness and strength, • High wear resistance, • Stable and low coefficient of friction. These properties must likewise be specially adjustable and repeatable. The consequence of this requirement is that it must be possible to influence the properties of the coatings within broad limits. For example, copper coatings are expected to have high electrical conductivity for applications in electrical engineering and electronics, but high hardness as a coating material for printing cylinders. Combinations of two or more properties such as high corrosion resistance and high wear resistance are generally required. It is likewise common for combinations of properties that are inherently contradictory, such as high tensile strength together with high ductility, to be required. In any case, the metallic coatings applied are expected to fulfill their intended decorative and functional tasks throughout their service life. Other requests by designers and engineers directed at the electroplating industry are expressed in the following formulations: • As few requirements as possible should be placed on the base material, the component's structural design, and production or assembly technology. • The properties of the structural material must not undergo any change during coating. • The dimensional accuracy of the component must be preserved. • Repair of the coated component must be possible without problems. • Coating and delivery should take place as quickly as possible and at extremely low cost. In addition to designers and engineers who understand these demands and requests, electroplaters must also be aware that coating properties are influenced by numerous factors. Among these are, in addition to others, the type and nature of the base material, the nature of the surface of the component made from it, the cleaning and pre-treatment of the component surface, the composition of the deposition electrolyte, the deposition conditions, and finally the mechanical, thermal or chemical finishing of the composite system component/layer. Starting from the fact that various atomic interactions take place between the base material and the layer, the condition and quality of the base material's surface is of special importance. It must be chemically and physically homogeneous, contain no pores or cracks, show no doubling, shrinkage, or voids. In the case of non-metallic materials, the surface must nevertheless be activatable. The design of the component to be coated is also of decisive importance. In technical jargon, this is called "design suitable for electroplating." In addition to the correct selection of the base material, this first and foremost refers to all design and construction measures that enable optimal coating. From this perspective, the demands of electroplating technology on designers and engineers can be formulated as follows: • Design exposed areas such as edges, corners, and profiles to be as suitable as possible for electroplating. • Take constructive measures to allow gases generated during electroplating to escape unimpeded. • Ensure that process solutions can drip from the component surface. • Design the structure so that coated surfaces can be reprocessed by machining. • If possible, assemble components from the same types of materials. • Ensure that parts to be riveted to each other are electroplated before riveting. • In the case of soldered connections, bear in mind that these can only be galvanized with greater effort. • Design welded connections so that the weld seams and thermally affected adjacent areas can be reprocessed. • Do not supply pipes and other hollow sections that only need external galvanizing with internal cavities that are open on the inside. • Design cast products so that they do not lock or stick to each other during drum electroplating. Designers and engineers should be informed that improperly designed workpieces and components not only lead to uneven coating thickness distribution but also cause irregularities on the coating surface. When exposed to thermal, mechanical, or chemical stresses, these can crack and expose the component to harmful environmental effects at unprotected points. The fact that this can lead to serious and often unpredictable deterioration in the functionality of the composite system component/layer should be particularly emphasized. Figure 1 shows some examples illustrating the difference between "unsuitable" and "suitable" component design. These examples clearly demonstrate how important it is for constructive component design to be adapted to optimal coating conditions already in the planning phase. The principle that the functionality of a composite system results from the combination of material properties, the component's structural design, and the coating's properties must always be kept in mind.

Ecology and Environment

The task of electroplating is to provide metallic coatings in a cost-effective and appropriate manner to protect the surfaces of components, tools, everyday-use goods, and mass-produced products from harmful external effects, ensure their functional efficiency, and extend their service life. Significant progress has been achieved in this regard through continuous optimization of electroplating processes. However, this is not sufficient; electroplating technology must continue to make every effort to fulfill this task in as environmentally friendly a manner as possible and taking ecological considerations into account. This includes, on the one hand, the economical use of raw materials and energy, and on the other hand, the disposal of waste products. For this reason, electroplating facilities are generally equipped with special facilities and processes that ensure the recovery of valuable materials, chemicals, and water, as well as the elimination of pollutants in exhaust air and wastewater. Although the installation and operation of such facilities require additional and possibly significant investments, these are absolutely necessary. Through the development and implementation of low-waste technologies and progressive rinsing techniques, it has been possible to greatly reduce the amount of labor and energy required for the recovery of valuable materials and for the treatment of exhaust air and wastewater. Furthermore, work continues on using electrolytes that do not contain complex-forming agents with lower metal ion concentrations to an ever-greater extent and on keeping the required rinsing water quantities as low as possible. A forward-looking approach in this direction appears to be the method called process-integrated environmental protection. This is a technology expected to eliminate the causes of environmental pollution by effectively reducing material losses at the outset, rather than attempting to limit harmful effects afterwards. This work method, known as minimization of material loss, is also intended to help integrate economic and ecological primary measures into the production process and thereby largely create closed internal material cycles. The most important objective here should be to optimize the closure of the internal material cycle and the use of external waste in such a way that environmental compatibility, process safety, and quality assurance can be achieved along with effective cost reduction.   Sources: • Vorbehandlung als Herausforderung, Metalloberflaeche, RITUPER • Reinigung in die Fertigung integrieren, Metalloberflaeche, LANDAU • Prozesssicherheit in der Galvanotechnik, Metalloberflaeche, PENZ • Wirtschaftliche und umweltgerechte Teilereinigung, Galvanotechnik, FALLOT   İzzet Aydın General Director Hillebrand Chemicals Chemical Marketing Ltd. Co.