Laser drilling of micro holes of extraordinary quality and high aspect ratio is accomplished by laser-induced plasma erosion and requires a dedicated conditioning of the laser beam. In order to generate holes of high circularity and defined taper in metal sheets of up to 2 mm thickness, the beam needs to become conditioned using dedicated helical drilling optics. Within this drilling head, the beam profile is optimized such that the laser beam is rotating in itself and impingement angle as well as diameter of rotation trajectory onto the work piece can be fully controlled.

Under such conditions, positive as well as negative taper can be achieved and minimum hole diameters of 40 µm can be obtained. The deviation from perfect circularity are on the order of just a few percent of the hole diameter. Resulting from the plasma erosion process used to generate the micro holes, its claddings are extraordinarily smooth and the cone envelope lines are markedly straight. For 1 mm thick metal substrates, the ratio of entrance and exit diameter of the micro holes (typically amounting between 70 and 110 µm) can be freely controlled between 2:1 and 1:2. While the utilisation of ultrashort pulsed laser can help reducing the heat-affect zones well below 1 µm, superficial damage to the metal by redeposited ablation products is significantly reduced by employing dedicated machining algorithms.

3D-Micromac offers this optic as an option to different micromachining systems, for instance microDRILL and customized solutions. For further information, please call our regional sales partner.