With laser drilling, nearly all solid materials, from metals to diamonds, can be drilled by selection of a suitable laser. Minute holes, impossible to create with mechanical processes, are possible. Laser drilling is performed contact-free, and thanks to extremely small optical systems, drilling is possible at locations that otherwise would be very difficult to reach. In this process, the laser beam melts and evaporates the material. This increases the material volume in the drill hole, and a high vapor pressure is created. The vapor pressure drives the melt out of the drill hole.
There are different drilling processes:
Single-pulse drilling and percussion drilling
Single-pulse drilling can be used for penetrating drill holes with small material thicknesses or to create a few micrometers of depth, for example for roughening of surfaces for gluing or coating processes. Percussion drilling realizes the desired drilling depth with thicker materials by means of a series of laser pulses with a short pulse duration and low pulse energy. The created holes are deeper, more precise, and have a smaller hole diameter than with single-pulse drilling.
Trepanning drilling is a combined drilling and cutting process that is used to obtain larger diameters. Here, the starting hole is created by percussion drilling by several laser pulses. The laser beam then travels over the material in increasingly larger circular tracks over the workpiece and enlarges the initial hole. With this, the melted material is displaced downward from the drill hole.
Helical drilling is used to create large and deep drill holes with high quality. In this process, no initial hole is created, but the drilling is done by many laser pulses in a circular track into the workpiece. With this, the material is displaced upwards. The focus is controlled so that it always remains at the bottom of the hole. As soon as the material has been penetrated, the laser can be used to widen the bottom of the drilling and to smoothen the edges.