Löten von Aluminiummatrix‐Verbundwerkstoffen mit modifizierten Löttechnologien

Soldering of aluminium matrix composites by modified technologies The correct procedure is for the soldering of aluminium‐matrix‐composites very important. Two basic facts must be given. On the one hand the oxides on the surface must be destroyed and removed for wetting. On the other hand the thermal influence on the basic material must be kept down. Otherwise the intended profile of the composites will change. That’s why the work temperature of the solder must be less than 300 °C. The tin‐based solders offer large potentials. However the low strength and creep stability of these solders have a harmful effect. For improving the characteristics oft the solder reinforcement with ceramic particles is meaningful. Presented were selected results of the particles containing solders. Thereby the compound strength and the creep behavior are regarded.     

Ein‐Blick in die Nano‐Elektronik: Bausteine,Funktionsprinzipien und virtuelle Reisen

In sight into nano‐electronics: Devices, functional principles and a virtual trip Electronics captures the nanocosmos at high‐speed like no other today’s technology. The fact that modern very complex products are based upon some quartz‐sand and a couple of metallic additives is shown by the recent exhibit “from sand to superchip” initiated by the German Federal Ministry of Education and Research. The over‐all value added chain of Germany’s semiconductor‐industry is presented vividly. Already today the size of crucial components is in the range of nanometers and in some places even down to the thickness of a few atom layers only. Chip producers are facing increasing challenges. They must develop new materials and more and more complex processes need to be controlled. Germany is now established as a leading location of nanoeletronics research and production. This was achieved not only by supporting the settlement of new chipfactories such as AMD and Infineon/Qimonda in Dresden, but also by focusing competence. Prominent examples are a high‐end photomask research and production facility (AMTC Dresden), the center of nanoelectronics technologies (CNT) in Dresden as well as the foundation of edacentrum (EDA‐Electronic Design Automation) in Hannover. A profound insight into the world of nanoelectronics is given playfully by ?Nanoreisen”?, which addresses the interested public.     

„Ideale“ Lötverbindung und „optimale“ Lötverbindung

If due to the market analysis a company makes the decision for the production of a new product by application of soldering and special the soldering with temporarily liquid solder, this one is then made specifically after that the company specific construction and production preparation. Either the decision for soldering is technically and/or economically well‐founded or she is even unavoidable by so‐called mixed material connections in the assemblies. This hybrid design finds application increasing today. In the contribution on hand the analysis and assessment of the soldering theory and practice is carried out under the point of view of the possible production of “ideal soldered connections” and “optimal soldered connections”.     

Elastizitätstheoretische Lösung des kreisförmigen Einschlusses in unendlicher Scheibe mittels der Beziehungen zwischen Loch‐ und Einschlussproblem

The method applied for the derivation of an elastic solution of an infinite plate with a circular inclusion of mismatching stiffness under uniform remote tension stress is based on the special deformation characteristic of this inclusion geometry. Outgoing from the analysis of the plate with a circular hole is the exact solution of the general inclusion problem obtained by superposition of a specific inner stress field.     

Photoelektronenspektroskopie — eine Methode zur Lösung anwendungsorientierter Probleme der Katalyse,der Elektronik/Elektrotechnik sowie der Werkstoffentwicklung

Photoelectron-Spectroscopy (XPS) is an analytical method to get quantitative and qualitative informations about element distribution and chemical bonding on solid surfaces and in near surface layers. By means of recent publications about catalysis research, electronics/electrotechnics as well as material development and refinement the performance of XPS will be outlined.     

Gefilterte Bogenbeschichtung – alte Probleme und neue Lösungen

Currently, the vacuum arc deposition (VAD) technique is well established in industry, primarily to deposit wear protective hard coatings such as metal nitrides and carbides onto tools and components. From the beginning of the industrial development of the vacuum arc deposition, it was obvious that the emission of macroparticles or droplets is a fundamental drawback of this coating technology. The emission is caused by the highly dynamic process of plasma generation and limits the fields of application significantly. Different methods have been proposed to minimize the macroparticle flux to the substrate surface. But the only way to hinder droplets from reaching the substrate reliable is to separate the plasma from particles by using curved magnetic fields. This filtered arc technique has proven its superiority of depositing high quality films compared to conventional arc applications in numerous laboratory tests. Current demands have stimulated new developments at the Fraunhofer IWS of more compact and higher productive filtered arc sources. One important application of ultra thin protective films is the topcoat on hard disks. In order to increase the storage density, the head‐to‐media spacing as well as the thickness of the overcoat has been reduced continuously. Until now, the thickness of the sputtered films was reduced to about 4 nm. The limit for this technology seems to be achieved. Filtered arc deposition is one of the most promising candidates for the deposition of thinner films – down to 1.3 nm with an even improved mechanical and chemical resistance. Another application area is the manufacturing of metallic lines and interconnections with high aspect ratios in the deep sub‐micron region in microelectronics. The excellent properties of this new filtered source for the deposition of conducting lines in microelectronics were been demonstrated. Actually, the technology for the subsequent deposition of barrier films and conducting wires is under development. Besides the micro technologies, there are a lot of applications requiring higher quality but not (yet) such a perfect film surface. Therefore, using a quite simple filter design – the so‐called Venetian blind filter – a filter unit was developed which can be used at the common industrial vacuum arc deposition machines. The filter does not reduce the deposition area, so the standard deposition processes can be used furthermore. With this filter, the number of droplets can reduced dramatically. A plasma transmission through the filter of approximately 20 % could be measured. Such filter module was realized and is in use now.     

Ermüdungsverhalten des hochstickstofflegierten und nickelfreien Stahles X13CrMnMo18‐14‐3 an Luft und in Ringerlösung

Fatigue Behaviour of the High‐nitrogen and Ni‐free Steel X13CrMnMo18‐14‐3 in Air and in Ringer's Solution The present work presents a new austenitic high‐nitrogen and nickel‐free steel X13CrMnMoN18‐14‐3, (1.4452). The cyclic fatigue behaviour of this materials was investigated under simulated body conditions. When compared to solution annealed CrNiMo‐steels, fatigue endurance limit is higher. The pitting potential in Ringer's solution was measured being 1.1 V, which is in the range of CoCr29Mo6. Hence, the austenitic high‐nitrogen steel X13CrMnMoN18‐14‐3 may be a promising alternative to CrNiMo‐steels due to the absence of nickel and improved mechanical and chemical properties.     

Vom Lötbruch bis zum Rotbruch – Gemeinsamkeiten und Besonderheiten

The soldering embrittlement is a brazing defect due to local or continuous material separation. It can limit the guarantee and reliability of brazed joints or even render it impossible. Normally this material separation occurs in an intercrystalline way along the grain boundaries or even sub grain boundaries. Thus the liquid metal embrittlement belongs macroscopically to the embrittlements which were influenced by applied procedures on basic materials. The character of liquid metal embrittlement and the kinetic of crack formation can be compared to similar material separations such as reheat cracks next to welding line or red shortness cracks during the metal forming process. In the present article the authors compare these intercrystalline material separations and specify the common similarities and characteristics in which the brazing joints are focused.     

Löten von Diamant – Grenzflächenreaktionen. und Benetzung

Diamond Brazing – Interfacial Reactions and Wetting Diamond tools are increasingly gaining importance as cutting materials for various construction materials. The quality of synthetic diamonds, monocrystalline as well as polycrystalline or CVD‐diamonds has been significantly improved over the last years. Integrating these cutting materials requires adequate joining technologies that produce sound joints without exposing the temperature sensitive diamond to too elevated temperatures. The paper highlights current developments in the joining of synthetic diamonds to steel and cemented carbide. Owing to their covalent atomic bonding diamonds cannot easily be wetted and joined by employing conventional brazing alloys. Hence, active agents are needed to foster an interfacial reaction. Different active filler concepts are presented and discussed regarding their joint formation. The brazing temperatures influence not only possible diamond degradation but also the interfacial decomposition of the diamond due to the formation of corresponding reaction layers.Active brazing, monocrystalline     

Lötbarkeitsuntersuchungen in der Dickschicht-Hybridmikroelektronik

Thick Film Hybrid Microelectronics – Aspects of Solderability The interconnection techniques for microelectric circuits requires a high level of reliability. Soft solder applications are widely used because of their economy. The quality of bonds made in this technology is determined by the solderability of the materials used. Starting with a definition of the solderability this paper describes a method to determine the solderability of thick film metallizations.