Efficient drilling of amorphous alloy foils using low-energy long pulses of a Nd:YAG laser

Laser drilling of amorphous alloy foils was conducted using low-energy long pulses (LP) generated using a Nd:YAG laser. Results showed that LP can drill an amorphous alloy foil more efficiently than a nanosecond pulse (NSP) can: An LP at 1 mJ can open a through-hole on an amorphous alloy foil with 25 µm thickness although a single-shot NSP at 20 mJ formed a crater with ca. 3 µm depth. From these findings, we infer that the markedly higher drilling efficiency of a low-energy LP than that of NSP is attributable to 1) lower plasma generation by LP than by NSP, and 2) continuous heating of the target material by multiple sub-pulses in an LP. Results also demonstrate that low-energy LP drilling is applicable to various metal foils and that the drilling efficiency depends on the metal species. The results of the analysis of the relation between some physical properties of the metals and the drilling efficiency suggested that the drilling would proceed via melting of materials.