Fig. 1. Experimental setup of five-axis femtosecond laser drilling, experimental materials, and drilling strategy

Fig. 2. Influence of laser parameters on sidewall taper. (a) Sidewall taper versus n under different laser parameters; (b) efficiency of edge trimming by laser under different laser energy values; (c) efficiency of edge trimming by laser under different laser frequencies; (d) efficiency of edge trimming by laser under different laser scanning speeds

Fig. 3. Influence of line spacing of spiral lines on material removal uniformity at micro-hole bottom. (a) 7 μm; (b) 9 μm; (c) 11 μm; (d) 13 μm; (e) 15 μm; (f) 17 μm

Fig. 4. Processing strategy and experimental results for sidewall taper regulation

Fig. 5. Experimental results of regulation of blind hole size. (a) Radius of 350 μm; (b) radius of 190 μm; (c) radius of 138 μm; (d) radius of 94 μm

Fig. 6. Detection of machining quality at blind hole bottom. (a) Morphology of sidewall; (b) morphology of bottom; (c) profile morphology of copper layer