At HSG-IMAT the precision assembly of micro systems became increasingly important in recent years. The challenge is to reach a high accuracy of about 10 μm between the assembled elements. At the same time it is important that the applied processes are suitable for low cost manufacturing. Attempts were made to achieve these requirements by means of automatic assembly processes based on MID and PCB. The results of the development at HSG-IMAT are shown in this contribution using the example of an optical module of a rotary encoder. Thereby, the assembly of the laser diode and lens requires special attention to achieve the specified positioning tolerances.