Two-Side Laser Processing Method for Producing High Aspect Ratio Microholes

Abstract

Laser microprocessing 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 noncontact processing of a wide range of materials. However, there are some constrains that limit the applications of this technology, i.e., taper angles on sidewalls, 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 situ, on-machine 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 regard to achievable aspect ratios and holes' dimensional and geometrical accuracy and thus to make conclusions about its capabilities.

On-machine and in-process surface metrology for precision manufacturing

“…In 3D optical microscopy, the magnification of the surface area in the lateral directions is made by using the objective as an imaging lens. This is basically the same as 2D optical microscopy that has been employed for on-machine measurement of edge contour profile, such as a tool [260], a micro-hole [176] or a die coater slit [59]. The lateral resolution is determined by the size of the field of view and the number of the camera pixels or by the diffraction limit, depending on the aperture used.…”

Effects of Top-hat Laser Beam Processing and Scanning Strategies in Laser Micro-Structuring

“…Furthermore, there is a consistent trend for miniaturization of new and existing devices that drives the advances in laser micro-machining. Efforts to achieve high geometrical accuracy, especially to minimize the tapering effect on side walls of structures fabricated by laser micro-machining, was the focus of many investigations, and different approaches to address this issue were suggested by researchers [10][11][12][13][14]. The main difficulties with these solutions are either the high accuracy requirements for the movements of mechanical stages, or their low repeatability and also their applicability for only specific structures.…”

Experimental investigation of processing disturbances in laser surface patterning

“…Especially, the process can be considered in control in regards to the resulting surface profiles, and thus they can be employed for inline monitoring, e.g. by integrating a focus variation sensor in laser processing setups [35].…”