Techniques for improving surface quality after laser milling

The major drawbacks of long-pulse laser milling are the deposition of debris on the target surface and the formation of recast layers. The removal of debris becomes very important when laser milling is employed as a technology for microstructuring and especially for machining micro-cavities for a number of replication technologies. For such applications, the surface quality of the manufactured geometry becomes even more important due to the micro sizes of the machined features. A recast layer is also formed on the laser-milled surfaces. It generally consists of metal oxides and has different material properties from those of the bulk of the material. This paper discusses cleaning techniques for removing the debris, contaminations, and recast layers from micro-structures, and thus improving the surface quality of finished products. In particular, four techniques are investigated in this research: laser cleaning, ultrasonic cleaning, deoxidization (or pickling), and electrochemical polishing.