Two-side laser processing method for producing high aspect ratio microholes

Laser micro processing is a very attractive option for a growing number of industrial applications due to its intrinsic characteristics, such as high flexibility and process control and also capabilities for non-contact processing of a wide range of materials. However, there are some constrains that limit the applications of this technology, i.e. taper angles on side walls, edge quality, geometrical accuracy and achievable aspect ratios of produced structures. To address these process limitations a new method for two-side laser processing is proposed in this research. The method is described with a special focus on key enabling technologies for achieving high accuracy and repeatability in two-side laser drilling. The pilot implementation of the proposed processing configuration and technologies is discussed together with an in-process inspection procedure to verify the achievable positional and geometrical accuracy. It is demonstrated that alignment accuracy better than 10 µm is achievable using this pilot two-side laser processing platform. In addition, the morphology of holes with circular and square cross-sections produced with one-side laser drilling and the proposed method was compared in regards to achievable aspect ratios and holes’ dimensional and geometrical accuracy and thus to make conclusions about its capabilities.