These days most common way to produce electrical components like LEDs, solar cells or transistors is a batch process. Therefore a lot of identical components are processed parallel on one big wafer and eventually each chip has to be singulated. Currently two dicing technologies have established themselves, which can be devided in mechanical blade sawing and laser based processes with nanosecond lasers. In contrast to these technologies, laser dicing with picosecond lasers offers fundamental advantages like smaller kerf width and marginal heat effected zones. In this paper the cutting process of Si wafers with ps lasers is investigated with regard to optimized process parameters like pulse energy, polarization and overlap.
The increasing use of plastics as a construction material has given rise to the problem of how to join dissimilar materials. For the production of hybrid plastic-metal components, several processes are possible. In a new joining method LIFTECA (R), recently developed at the Fraunhofer Institute for Laser Technology, a part or a defined area of a part is heated by laser radiation through the plastic component with which it is to be joined. The part is held in contact with the plastic component under mechanical pressure and heated; then, further mechanical pressure is applied to press it into the plastic material. A stable positive bond is achieved during cooling, provided that a suitable component geometry has been selected. An important aspect of the process is that the part to be heated should have a higher melting point than the plastic component with which it is to be joined. The more heat resistant of the two parts/components can be metal, ceramic, or a heat-resistant plastic. The high energy density of the laser beam permits the heating stage to be accomplished very rapidly. Another approach is pursued within the Cluster of Excellence "Integrative Production Technology for High-Wage Countries" of the RWTH Aachen University. Multiple irradiation strategies in line with the choice of the material, the beam source, and the pretreatment of the samples are investigated. In a first experimental series, the influence of the surface structure on the joining process is examined. A structure in dot, line, and cross pattern is implemented on the surface of stainless-steel samples with Nd:YAG laser radiation. Afterwards, these samples are joined with transparent plastic samples. For the laser beam transmission joining process, contour or quasi-simultaneous irradiation strategies are considered while using diode laser power. The results show promising achievements, with good strength being obtained
Molding of micro structures by injection molding leads to special requirements for the molds e.g. regarding wear resistance and low release forces of the molded components. At the same time it is not allowed to affect the replication precision. Physical vapor deposition (PVD) is one of the promising technologies for applying coatings with adapted properties like high hardness, low roughness, low Young's modulus and less adhesion to the melt of polymers. Physical vapor deposition technology allows the deposition of thin films on micro structures. Therefore, the influence of these PVD layers on the contour accuracy of the replicated micro structures has to be investigated. For this purpose injection mold inserts were laser structured with micro structures of different sizes and afterwards coated with two different coatings, which were deposited by a magnetron sputter ion plating PVD technology. After deposition, the coatings were analyzed by techniques regarding hardness, Young's modulus and morphology. The geometries of the micro structures were analyzed by scanning electron microscopy before and after coating. Afterwards, the coated mold inserts were used for injection molding experiments. During the injection molding process, a conventional and a variothermal temperature control of the molds were used. The molded parts were analyzed regarding roughness, structure height and structure width by means of laser microscopy
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