Processing Techniques and System Technology for Precise and Productive Microdrilling in Metals

The fabrication of microstructures in metals employing ultrashort laser pulses has been under study since the middle of the 1990s. Over many years, extraordinary precision and machining quality have been demonstrated in surface patterning, cutting and drilling applications. However, apart from some exceptions, micromachining applications with ultrashort laser pulses could not be used in industrial production because of insufficient throughput until the late 2000s. This was the case particularly for microdrilling applications, where processing times easily reached several minutes per hole. This situation has changed fundamentally in recent years. In 2008, industry standard picosecond laser sources with average powers of 50 W combined with repetition rates up to 1000 kHz have been launched onto the market. In the present chapter, it is shown that these newly available laser specifications can be utilized for efficient and high-quality drilling techniques, the basic principles of which will be explained in combination with the necessary engineering expertise. A beam steering system for helical drilling with rotating beam profile will be presented. Finally, various diagnostic methods will be discussed with regard to visualization and fundamental understanding of ablation processes, but also as a basis for process monitoring and control.