In dental prosthodontics, miniaturized unit assembly systems are increasingly used in order to enable the optimized adaptation
of the prosthesis to the individual anatomic situation. To manufacture these miniaturized systems, there is the
need to cover the complete device, in the reported case made of polycarbonate, comprising among others springs that
apply pressure to fix and adjust the prosthesis. The laser is a suitable joining tool for applications in micro technology.
Therefore, laser transmission welding was investigated for joining the specific miniaturized components, so-called retention
modules. The housing was made of PC with carbon black. The cover consisted of transparent PC with a thickness of
400 μm along the joining contour. The wall thickness of the joining partners amounted to 400 μm.
The investigations presented in this paper include detailed examinations of the welding process with and without laser
mask. For both process variants, the influence of the main process parameters laser output power, welding speed and
focal position was studied. The process was qualified especially with regard to joining strength, swelling, process time,
reproducibility, accuracy and functionality of the complete assembly. It was examined how the positioning of the mask
determines the formation of the weld seam. The geometry of the retention module and the clamping were optimized. It
turned out that the clamping of the components is crucial for a reliable process. Optimized process conditions enable the
micro welding of plastic components for dental products considering the high requirements regarding functionality,
biocompatibility, lifetime, and esthetics. Laser transmission micro welding proved to be a suitable method to package the
final assembly without any refinishing operation.