Method for Producing a Series of Through Holes in a Layer of Material By Means of a Laser Beam

A method for producing a series of holes in a layer of material by means of a laser beam which is emitted from a laser and directed onto the layer of the material thereby forming a plasma as a result of the ablation of the material, said plasma being detected and a signal being generated from which a switching criterion for switching off the laser is derived, comprising:

• generating a signal during the production of each individual hole, detecting the time of the beginning of said signal generation and the time of the appearance of a falling edge that meets a predetermined edge criterion;
• storing said detected times so that they can be linked to each respective hole;
• switching off said laser at the time that a falling edge is detected, said detected falling edge indicating the production of one individual hole;
• calculating a length of time based on the difference between the two times detected for each hole;
• and comparing said length of time to a predetermined target length of time, as the quality criterion for the hole involved.