Flexible printed circuit board magnetic micromirror for laser marking/engraving

This paper presents a flexible printed circuit board (PCB) quasi-static magnetic micromirror, on which a portable laser marking/engraving machine is built. The micromirror consists of a flexible PCB structure (including two polyimide torsion beams, a middle seat with coils, and two support pads), two permanent magnets, and a mirror plate. The fabrication uses a flexible PCB process, in addition to dicing a silicon wafer for making the mirror plate. The mirror plate is bonded to the flexible PCB middle seat, which has high strain strength (maximum strain at yield similar to 3%) and high bonding yield with easy operation. The flexible PCB micromirror achieves a large quasi-static rotation, e.g. 13 degrees (optical), a low driving voltage (-0.4- + 0.4 v), and a low cost (a few dollars). Its aperture is large (4 x 4 nun) with high flatness (radius of curvature, ROC of similar to 10 m). A prime method is proposed to address the drift/ creep problem associated with the flexible PCB micromirror's quasi-static rotation. A low cost and portable laser marking/engraving machine is built with the following performance: working area (22 x 17 mm(2)), size (116 x 43 x 55 mm(3)), laser power (0.23 W), speed 2 mm s(-1).