Fig. 1: Principle of stereolithography

Fig. 2: Prototype system for microstereolithography

Fig. 3: REM images of micromechanic components fabricated by stereolithography (right), CAD model

Fig. 4: Movable micromechanic component with match for size comparison. Link to the MSL video (in German language).

Stereolithography is a generative manufacturing process suited for the production of complex three-dimensional components (Fig. 1). In order to make this process accessible also to microsystem technology, a high-resolution prototype machine that allows the production of microparts in small and medium-sized series was developed at the Laser Zentrum Hannover e.V. (Fig. 2). For this purpose, the process-determining system technology such as laser beam source and handling technology, but also suitable microsystem materials, were specifically chosen.

Fluid polymers known as photoresists are processed layer upon layer under the effect of laser radiation to form three-dimensional components. A focused laser beam is flexibly positioned onto the surface of the polymer and that way initiates local solidification. By means of a targeted path control of the laser beam, highly complex three-dimensional geometries can be generated. The three-dimensional component builds up in a layer-by-layer process as the physical representation of a previously generated CAD model.

In the framework of the European research project Rapid Production Tool for Micro Mechanical Systems (PRONTO), users from rapid prototyping industry cooperated with scientists from laser technology and material science. Aside from the development of process and system technology, a hybrid polymer of the Ormocer® type that is suitable for microstereolithography was generated and adapted to the high requirments in microfabrication by targeted modifications. Ormocer®s are organically modified alcoxysilanes that are synthesized to form oligomers with an inorganic core. Using lithographic methods, their organic functional groups can be crosslinked. The generated organic-inorganic network has properties (e.g. hardness, chemical stability) between those of inorganic ceramics and organic polymers. During the research project, additives were introduced into the base polymer, which allows for a vertical process resolution in the range of 10 µm. Micromechanic precision components were already able to be fabricated successfully (Figs. 3 and 4. Link to the MSL video - in German language -). Further miniturization is conceivable by adapting the machine and material parameters.

How can we help you?

In precision fabrication of complex microsystem components, the Laser Zentrum Hannover e.V. offers you the following:

• Design: We verify and optimize your CAD draft for the fabrication of precision components by stereolithography.
• Process and material development: Together with our cooperating partners, we develop specific materials that meet your requirements.
• Fabrication of adapted precision components for applications in medicine, micromechanics, microfluidics, etc.

History of microstereolithography at the LZH

Publications

Conference contributions

Neumeister, A.; Czerner, S.; Ostendorf, A.: Metal and polymer micro parts generated by laser rapid prototyping. In: Proc. of LPM2006-The 4th International Congress on Laser Advanced Materials Processing LAMP, May 16th-19th 2006, Kyoto/ Japan

Neumeister, A.; Himmelhuber, R.; Kienzl, A.; Materlik, C.; Stute, U.; Ostendorf, A.: Direct manufacturing of mechanical assemblies using micro stereo lithography. In: Proc. of Rapid. May 16th-17th 2006, Erfurt/ Germany

Neumeister, A.; Himmelhuber, R.; Temme, T.; Stute, U.: Generation of micro mechanical devices using stereo lithography. In: Proc. of Solid Freeform Fabrication Symposium P. 12-24. August 14th-16th 2006, Austin, Texas/ USA

Neumeister, A., Himmelhuber, R., Temme, T., Stute, U., Ostendorf, A.: Layer based fabrication of micro mechanical systems using laser induced photo polymerisation. In: Proc. of LIM2007-4th International WLT-Conference on Lasers in Manufacturing ISBN 978-3-00-021449-3 P. 735-739. June 18th-22th 2007, Munich/ Germany

Neumeister, A.; Himmelhuber, R.; Materlik, C.; Temme, T.; Pape, F.; Gatzen, H.; Ostendorf, A.: Three-dimensional micro fabrication of mechanical systems using laser based stereo lithography. In: Proc. of LPM2007-the 8th International Symposium on Laser Precision Microfabrication, April 24th-28th 2007, Vienna/ Austria

Neumeister, A., Materlik, C., Temme, T., Himmelhuber, R., Ostendorf, A.: Process accuracy during laser based stereo lithography and production of Ormocer micro systems with related mechanical properties. In: Proc. of VRAP2007-the 3rd International Conference on advanced research in Virtual and Rapid Prototyping, ISBN 978-0-415-41602-3 (Virtual and Rapid Manufacturing) P. 501-507. September 24th-29th 2007, Leiria/ Portugal

Neumeister, A., Temme, T., Himmelhuber, R., Klukowska, A., Ostendorf, A.: Towards Mirco Rapid Manufacturing with functionalized materials: material properties and process accuracy during stereo lithography. In: Proc. of LEM21-the 4th International Conference on Leading Edge Manufacturing P. 953-956. November 7th-9th 2007, Fukuoka/ Japan

Publications in magazines

Neumeister, A.: 3D-Mikroproduktion in einem Schichtbetrieb. In: K-Zeitung 5, 2006, P. 33

Neumeister, A.: Dreidimensional dank Laser. In: Industrieanzeiger 129, 2007 P. 34-35

Neumeister, A.: Schicht um Schicht Präzision. In: Mikroproduktion 03, 2007, P. 40-42

Neumeister, A., Klukowska, A.: Non-assembly micro production of multi-component systems using stereo lithography. In mst-news 05 2007, P. 44-46