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Joining of dissimilar materials is gaining more and more importance especially in the automotive industry. The latest international initiatives concerning the average fleet CO2 -emissions are forcing manufacturers to reduce fuel consumption and exhaust gas output. This can mainly be achieved by reducing the weight of the vehicles. New methods for weight optimization have been enabled by material selections adapted to local strength requirements. While plastics are characterized by low density, low price, and literally unlimited shaping, metals can withstand distinctly higher mechanical loads. Hybrid components combine the contradictory characteristics of plastics and metal and thus can lead to advantageous construction part properties. As a result, light and concomitantly stiff components can be produced. The need for joining these dissimilar materials without using additional material such as adhesives or primers is a central challenge. A new approach to overcome the p roblems of state-of-the-art technologies is using laser radiation to ablate the metal surface in order to create microstructures with undercut grooves. When the above placed plastic is melted with laser radiation or induction joining, the material expands into these structures through external clamping pressure and after setting the joining results due to microclamping. In this paper, the influence of different microstructure geometries and the process parameters of this innovative approach are presented and discussed in detail

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In comparison with competitive joining methods, the joining technology ''adhesive bonding'', provides advantages in the low-stress joining of similar and dissimilar material combinations. As far as the micro-range is concerned, this technology is particularly suitable for the joining of hybrid micro-systems made of different materials and featuring complex geometries. The variety of available adhesives allows the adaptation of the process to the specific joining task. If the technology is transferred from the macro-range to the micro-range, the dispensing and application of the requested minimal adhesive volumes is one of the fundamental challenges. The process limits of nowadays-used micro-dispensing systems are characterised by the minimally dispensable adhesive volume and also by the flexibility with regard to the applicable adhesives and dispensable layout. The objective of the research work, which is specified in this paper is the expansion of the process limits up to smaller volumes and also the guarantee of flexible handling and a high-process stability. This has been the motivation for the Welding and Joining Institute of the RWTH Aachen to develop a micro-dispensing unit for spot and linear adhesive application. The unit comprises a positive-displacement dispensing system with integrated adhesive tempering, process gas supply and process optics. A reproducible dispensing process requires the adhesive reservoir to be absolutely free from gas. For this reason, a one-way system has been developed which allows degasification before the actual dispensing process takes place. Different degasification principles have, in this connection, been tested with regard to their achievement potential. The one-way system further reduces expenditure for cleaning, maintaining and setting-up of the unit. The unit allows the determination of the important parameters influencing the line dispensing of unfilled adhesives with a line width of \50 lm.

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