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|1. (WO2018162386) METHOD FOR PRODUCING A TECHNICAL MASK|
|Applicants:||LPKF LASER & ELECTRONICS AG
|Title:||METHOD FOR PRODUCING A TECHNICAL MASK|
The invention relates to a method for producing a technical mask (1) from a flat substrate (2), for example glass, sapphire or silicon. At least one opening of the mask (1) is produced by means of laser-induced deep etching, wherein the substrate (2) is transparent at least for the laser wavelength used during laser-induced deep etching. To this end, the substrate (2) is modified by the pulses of the laser along predefined machining lines (4) for isolating in particular closed contours (3). Local interruptions in the machining lines (4) in the form of connecting webs, known as break-out tabs, ensure that the contours (3) to be isolated are still initially connected to the flat substrate (2) after treatment with the etching solution. In the subsequent step, the flat substrate (2) pretreated in this way is treated with an etching solution, such as hydrofluoric acid (HF) or potassium hydroxide (KOH), as a result of which the non-modified regions of the substrate (2) are etched homogeneously and isotropically. The modified regions react anisotropically in relation to the non-treated regions of the substrate (2) and therefore directed depressions are initially formed at the treated sites until ultimately the material of the substrate (2) is completely dissolved at said sites.