Depending on component thickness as well as required quality (precision) and productivity (drilling duration), holes of approximately 1 μm to several millimeters in diameter are drilled into the workpiece by means of single pulse drilling, percussion drilling, trepanning, and helical drilling. The following table shows the distinctions among the various drilling methods with respect to diameter, depth and duration.
Single-pulse drilling can be performed “on the fly,” so that up to 300 holes per second with a diameter of 60 μm can be drilled into metal sheets of 1 mm in thickness. Trepanning, which involves relative movement between the workpiece and the laser beam, is used for drill hole diameters larger than approximately 300 μm. Helical drilling is used to create holes that have both highly precise geometry and superior metallurgical quality. Laser drilling is an alternative to methods such as electron beam drilling, electrical discharge machining, electrochemical drilling and ultrasound drilling. The use of “light as a tool” is preferred when the manufacturing process requires drill holes with diameters of approximately 1 to 500 μm and high aspect ratios (> 1:20) to be made under difficult conditions, such as those involving large inclination angles to the workpiece surface, or materials of high hardness (e.g. nickel-based alloys). Challenges exist with respect to the minimization of melt layers and the avoidance of micro cracks in the drill hole wall.