Mikrowellen‐PECVD für kontinuierliche Großflächenbeschichtung bei Atmosphärendruck

Microwave PECVD for continuous wide area coating at atmospheric pressure Plasma processes are applied for a variety of surface modifications. Examples are coatings to achieve an improved corrosion and scratch protection, or surface cleaning. Normally, these processes are vacuum based and therefore suitable to only a limited extend for large area industrial applications. By use of atmospheric pressure plasma technology integration in continuously working manufacturing lines is advantageously combined with lower costs and higher throughput. Microwave plasma sources present powerful modules for plasma enhanced chemical vapour deposition at atmospheric pressure. At Fraunhofer IWS processes and equipment as well as application specific materials are developed. The coatings are suitable for scratch resistant surfaces, barrier and corrosion protective layers or anti‐reflex layers on solar cells. The film properties achieved are comparable with those produced by low pressure processes.     

Abscheidung,Charakterisierung und Anwendung von Plasma‐Polymerschichten auf HMDSO‐Basis

Deposition, Characterisation and Application of HMDSO‐based Plasma Polymer Films High quality organosilicone coatings can be produced via plasma enhanced chemical vapor deposition of hexamethyldisiloxane (HMDSO). In this article aspects of deposition, analysis and application of HMDSO/O₂ processes are presented. The coatings’ organic/inorganic character can be adjusted by an appropriate combination of plasma power and gas mixture which is shown by XPS. Particularly multi layer and gradient layer systems can be deposited within the same process. Quantitative chemical depth profiling of such layer systems can be performed by secondary neutral mass spectrometry (SNMS). AFM investigations exhibit that the surface roughness of the coatings is determined by the appearance of hemispherical agglomerates, which is more pronounced, the more glass‐like the coatings are. As an example of use it is shown, that an appropriate HMDSO plasma treatment can distinctly improve the tribological behavior of elastomer devices. The presented work is done within a project of the German Federal Ministry of Education and Research (BMBF) entitled: “nano functionalization of interfaces for data‐, textile‐, building‐, medicine‐, bio‐, and aerospace‐ technology”.     

Anti‐Eis‐Oberflächenbeschichtungen

Anti‐icing coating — optimization by means of plasma technology Ice on surfaces can significantly limit the function of devices and has to be removed by processes with high energy consumption. E. g., the formation of ice on rotor blades of wind turbines is not desired, on the wings of aircrafts it is even dangerous. With the aid of plasma technology, the Fraunhofer IGB has developed an anti‐icing coating for polymeric surfaces. Water‐repellent micro‐ and nanostructured coatings are applied to polymer foils made of impact‐resistant and shockproof polyurethane. Optimization of various process parameters has made it possible to produce ultra‐thin coatings, which reduces the ice's adhesion by over 90 percent. The new nanostructured foils open a wide range of applications.     

Simulation von Plasma‐Beschichtungsprozessen

Simulation of plasma deposition processes – a new design tool for vacuum and plasma technology In the course of the up‐scaling of industrial deposition methods, the demands on productivity as well as on precision are continuously increasing. Both requirements are conflictive, since e. g. an increase of the substrate size for higher productivity often involves homogeneity issues. The increasing complexity and size of coating machines hampers their further enhancement by pure empirical approaches. For this reason, the research and development on coating technology nowadays becomes more focused on simulation methods. At Fraunhofer institute for surface engineering and thin Films we have developed a particle‐in‐cell monte carlo simulation environment for transport phenomena and gas discharges in the low‐pressure regime. This tool can be used for predictions and optimizations in the development of new deposition sources, furthermore the general insight in plasma discharge mechanisms can be improved.     

Plasmachemische Gasphasenabscheidung und Plasmaätzen bei Atmosphärendruck

Plasma enhanced Chemical Vapour Deposition and plasma etching at atmospheric pressure Plasma processes are applied for a variety of surface modifications. Examples are, e.g. coatings to achieve an improved corrosion and scratch protection, or surface cleaning and texturising. Since these processes, however, usually take place in vacuum, they are unfortunately not applicable for large area industrial use. Plasma enhanced CVD processes at atmospheric pressure enable the deposition of functional coatings on components and semi‐finished parts with in a continuous air‐to‐air process without the use of expensive vacuum systems. By their integration into in‐line production processes the substrate handling and the coating costs are definitely reduced. A thermal plasma source, basing on a linearly extended DC arc discharge at atmospheric pressure, has been tested for the deposition of silicon nitride at substrate temperature of less than 300° in a continuous PECVD process. Furthermore this source has been tested for plasma‐chemical etching and texturising of silicon as well.     

Großflächige Quellen f�r die industrielle Plasmatechnik

Plasma‐technological processes in modern thin film technologies for the refinement of surfaces are of constantly growing interest. Plasma‐technical procedures for the surface modification and film deposition mainly are contributed to the low pressure regime and use ion and/or plasma techniques. In particular plasma‐technological process concepts in the industrial field require adapted and scalable large area plasma sources. A new source concept, based on a coaxial structure, unites these specifications and permits plasma arrangements of nearly any required size.     

Beidseitige Innen‐ und Außenbeschichtung von PET‐Getränkeflaschen

Double‐sided interior and exterior coating of PET beverage bottles Plasma‐enhanced methods for the interior coating of PET beverage bottles have already been put into practice in the industry. Thereby the achieved barrier properties are limited due to defects in the coating, which emerge during the layer growth and allow a higher permeability. One possible way to improve barrier properties is the double‐sided coating. The implementation of the concept in form of a demonstrator plant is presented. By means of optical emission spectroscopy (OES) as a very versatile and easy to use method for the surveillance of industrial plasma processes, the influence of the gas composition on the plasma homogeneity and barrier properties of the coating is demonstrated. Permeation measurements are carried out, showing the potential of the combined coating process for the deposition of effective coatings.     

Dünnschichtfilter in der Telekommunikation

Market forces are pushing the performance of optics to their limits. Optical components must be developed to provide the best possible combination of manufacturability, performance and price. One vital step to success in creating WDM optics lies in a discipline that is often overlooked or misunderstood – coating engineering. A key technology for controlling light in WDM systems is the optical filter, which performs functions from simple filtering in multiplexers and demultiplexers, to more sophisticated functions in optical amplifiers, modulators and test equipment. The basic tool of multiplexing and demultiplexing devices, thin film filters offer accurate center wavelength, broad flattop passband and high isolation from adjacent and nonadjacent channels. Thin film filters are widely used for gain flattening, band splitting, C and L band separation and combining amplifier‐pump beams. Choosing the right thin‐film‐deposition process is essential for the efficiency and productivity of vacuum coating systems. LEYBOLD OPTICS has developed and optimized a comprehensive range of vacuum coating processes and process tools. LEYBOLD OPTICS has been proven the ability of producing shift‐free coatings on large substrate areas by means of PIAD (Plasma Ion Assisted Deposition) in many applications over the past ten years. The low loss and stress values achieved, especially with silica and tantala films, allows besides the production of narrow band pass filters (DWDM, CWDM) also the production of gain flattening filters (GFF). PIAD is considerably improving the properties of evaporated thin films by high energy ion bombardment during the growing of the film. PIAD allows to produce dense shift free thin films with high refractive index, good adhesion and extremely low absorption. With the Advanced Plasma Source (APS) LEYBOLD OPTICS has developed a high power plasma source for PIAD. The APS provides high ion current densities over a large surface area in a neutral plasma to produce high quality layers at a high productivity.     

Einsatztiefe der Industriellen Plasma‐ Oberflächentechnik im Maschinen‐ und Anlagenbau

The following article summarizes the main results of a market study about the use of Industrial Plasma‐Surface Treatment (IPS) in the German machinery and plant manufacturing branch conducted by the VDMA surface technology group. The results of the survey verify that during the past 20 years plasma‐based processes have become a state‐of‐the‐art technology. Today, more than 50 % of companies in the machinery and plant manufacturing industry employ IPS. Most of them prefer surface treatment of their products on a job coating basis. Merely some of the large suppliers have already acquired coating machines. The technology is particularly popular with manufacturers of precision tools and printing and paper equipment. The dominating argument for using plasma‐supported surface treatment within all segments of machine and plant construction is wearing protection of highly stressed tools. Other advantages of the technology are reduction of friction and the protection of metal against corrosion. At present a higher diffusion rate of IPS into the markets seems to be limited due to high costs and a qualification lag in the potential application sectors. Continuing public relation campains by suppliers, policy and assosications will achieve an improved level of utilisation in the near future.     

Plasma‐induzierte Polymerisation von Acrylaten

Plasma‐induced polymerisation of acrylates Plasma processes are suitable for the generation of complex polymers from simple monomeric compounds. For example, during the process of plasma polymerisation thin polymeric films are deposited onto a solid substrate from the vapour phase by plasma excitation. This process is characterized by the activation, ionization and fragmentation of gaseous precursors which subsequently combine to oligomers and polymers. Another possibility is the plasma‐induced polymerization of monomers within a liquid coating. Thereby, the polymerisation is initiated by reactive plasma species similar to other radiation induced polymerisation techniques such as UV or electron beam curing. However, one advantage of the plasma process is the spacious distribution of the plasma which enables curing of liquid coatings on complex shaped substrates. Herein results of the plasma‐induced polymerisation of acrylates are presented with respect to double bond conversion, surface energy and the generation of microstructures.     

Plasmapolymerschichten als Basis für maßgeschneiderte funktionale Oberflächen

Plasmapolymer coatings for tailor‐made functional surfaces The tailoring of surface properties via polymer coatings is currently a strongly pursued topic in various fields ranging from microsystem technology to bioanalytics. A precise tuning of surface properties, however, is only possible if chemically well‐defined processes are used that usually require reactive surface moieties to which molecules can be coupled. In this contribution we summarize studies that aimed at the modification of inert surfaces. For this purpose reactive groups at the surfaces are generated by plasma polymerisation of allyl amine which results in layers that contain amino groups. Initiator molecules for free radical polymerization processes are then coupled to these amino groups resulting in surfaces from which polymers can then be grown via surface‐initiated polymerization. Using these processes, polymer monolayers with very different properties can be generated by simply using different monomers.     

Herstellung und Untersuchung des Verschleißverhaltens von induktiv eingeschmolzenen Hardpaint‐Schutzschichten

Friction and wear processes generate significant economic damage annually in industrial production due to maintenance and repair costs as well as loss associated with production downtime. Wear‐resistant coatings are a measure for reducing wear. In this context, the novel hardpaint technology for coating of parts with a fusible metal powder composition is described. Components with complex geometries as well holes or undercuts can be coated easily and inexpensively. Two protective layers are discussed and characterized in terms of their microstructure. Density measurements, hardness tests and scanning electron microscopic investigations were carried out. Both powder layers were inductively melted after application and are based on a hard alloy (iron‐based) commonly used for plasma transferred arc powder surfacing. Abrasion wear resistance is evaluated based on the results of the wear tests and microstructural investigations. Furthermore the results are discussed in comparison to a martensitic fine‐grain steel (Hardox 450), which is commonly used in abrasively stressed areas. Compared to Hardox 450 both hardpaint coatings have a much more wear‐resistant behavior due to their hard phases. In addition, it was confirmed that the hardpaint technology is able to embed thermally sensitive fused tungsten carbides which are significantly increasing the wear resistance against abrasion.     

Nanokristalline Werkstoffe hergestellt mit dem Thermischen HF‐Plasma

Nano‐crystalline materials manufactured with the Thermal RF‐Plasma The Inductively Coupled Plasma (ICP) at atmospheric pressure is particularly suited for melting and evaporation of materials. The electrodeless ICP can be generated without limitation of the kind of plasma forming gases. Therefore, using an argon‐oxygen gas mixture as sheath gas of the ICP nanophase coatings can be processed by synthesis with metal‐organic liquid precursors injected in the hot plasma core. For depositions, the plasma jet has to be supersonic. For particles which impinge onto the substrate placed near the nozzle exit of the plasma torch thin and dense coatings are obtained with crystallite sizes of 30‐ 40 nm. The composition and the grain size of as‐deposited coatings are analyzed by XRD.     

Plasma‐aktivierte Bedampfung von flexiblen Materialien. Plasma‐activated vapour deposition on flexible substrates

The vacuum coating of flexible materials such as plastic webs is being used worldwide to change the surface properties for specific applications. The physical properties of interest e.g. density, hardness, refractive index and permeation are influenced by the microstructure of the coated layer. This paper describes, that this microstructure can be improved significantly by plasma enhanced evaporation techniques. At Fraunhofer Institute for Electron Beam and Plasma Technology (FEP), a method for plasma‐activated high rate deposition has been developed. This method is based on a hollow cathode arc discharge. This plasma‐source can be used for high productive roll coaters with boat evaporators or electron beam evaporators.     

Hochfrequenz-Plasmastrahlquellen — Neue Werkzeuge für industrielle teilchenstrahlgestützte Dünnschichtprozesse

Radio-Frequency Plasma Beam Sources — New tools for industrial particle beam induced thin film processes The applications for ion beam techniques has moved from pure base research to industry, mainly for microelectronics applications. Their potential for future surface and thin film processes are known to a large number of users and developers in this area. However such techniques are relative sophisticated and due to the costs industrial applications are often limited. RF-plasma beam technology with its specific advantages may be a possible candidate to overcome these restrictions. For some applications RF plasma beam technology is just on the step to an industrial use. But this technique is still not generally known, and its possibilities deserves more attention. Within this article the principle of plasma beam formation and construction of plasma beam formation and construction of plasma beam sources are described. Some application examples show the possibilities given to users with this technique.     

Holzoberflächenmodifikation mittels Atmosphärendruckplasma

Plasma surface modification of wood and wood‐based materials In this article, plasma technical, analytical and application relevant aspects of the plasma treatment of wood and wood‐based materials are presented. With the help of surface energy determinations and adhesion tests it is shown that the surfaces of wood and wood‐based materials can be changed for specific applications. Surface characteristics, which are application‐technological interesting for a later coating or adhesion, can be specifically generated with the use of air plasma. With surface energy determinations of wood and wood‐based materials, a significantly increased polar part of surface energy could be detected after a plasma treatment. Atomic force microscopy analyses of wood composites show that a plasma treatment with the use of ambient air effects an abrasion and a changed surface roughness. Tensile tests and shear tests of coated or adhered wood‐based materials with a plasma treatment show a clearly increased adherence.     

Nanocomposite‐Beschichtungen auf CBN‐Werkzeugen

Nanocomposite coatings on CBN‐tools CBN (cubic boron nitride) cutting materials are often used to improve the properties of cutting tools. This allows new applications and processes, which are not possible with common cutting materials (e.g. hard metals). Today CBN cutting materials are mostly coated to estimate the wear by an optical evaluation. Coatings on CBN cutting materials for enhancement of the tribological properties are normally not used. For improvement of the properties of used CBN tools during the cutting process a coating technology was developed. This technology combines the advantages of CBN cutting materials with the excellent properties (e.g. hardness, temperature stability) of nanostructured materials. Investigations with different coating systems and pre‐treatment processes were done to test the CBN cutting tools. These investigations have been shown, that nanocomposite coatings can be used to enhance the tool life of CBN cutting tools. Important for an increase in the tool life is a very good coating adhesion, which can be reached by special adhesion layers and an optimized coating structure.     

Plasmaprozesse für 3D‐Formteile

Plasma treatment and coating processes for 3D parts Many articles of our daily use are only able to feature their outstanding performance due to innovative plasma surface treatments. Semiconductor components like flat panel displays, solar panels, DVD / Blu‐ray Discs, as well as optical components, coated glass panes, cutting tools and other components with reduced wearing are just a few examples. One important quality feature is to reach uniform properties over the entire surface to be treated. In case of planar or slightly curved surfaces this can be relatively easily achieved by using common plasma sources. For complex 3D parts, the effort required for uniform surface treatments greatly increases, and complex movements of the 3D parts are often required to achieve uniformity. This article deals with the plasma surface treatment and plasma coating of such complex 3D parts referring to some selected examples.     

Low‐Vacuum Low‐Cost Deposition of Tribological Coatings

TiN coatings of some microns in thickness were deposited by different reactive plasma deposition technologies such as Magnetron Sputtering Magnetically Assisted, Arc Source Ion Plating and Sputter Ion Plating Plasma Assisted on various unheated metal parts. The source to substrate distances was between 8 and 25cm. Deposition were performed in specially designed plants in the pressure range between 10^‐3–10^‐1 mbar and under variable vacuum and plasma conditions. The experiments were carried out with the intention of obtaining isotropic coatings on substrates of complex geometry. Thickness distribution, morphology, hardness and tribological properties of these coatings were investigated and correlated with the gas pressures and the measured plasma parameters during deposition. The aim of this work was to find effective processes and conditions for the reliable low cost deposition of hard coatings at relatively high gas pressures. The investigations were supported by the European Union in the TIPCOAT‐Project: Brite EuRam BE‐3815/Contract BRPR‐CT97‐0397     

Hocheffiziente RF‐Impedanzanpassnetzwerke

Highly efficient rf impedance matching network for ICP sources Contrary to capacitive coupled plasmas (CCP) inductively coupled plasmas (ICP) offer a higher plasma density and therefore provide for higher deposition or etch rate and herewith a high efficiency for industrial low pressure plasma processes. In the following we will introduce a new impedance matching network, which was specifically developed for the requirements of the operation of inductive plasmas and especially for the use in an industrial application. For the application in production systems detailed knowledge of the plasma properties, like homogeneity and ion energy distribution is required. Plasma diagnostics and calculations of the plasma density distribution will be shown. Finally, the application in a production system, which fully automatically processes 1200 substrates of size 156 mm × 156 mm per hour on a compact 19 m² footprint, is introduced.