Multi-scan picosecond laser welding of non-optical contact soda lime glass

Nowadays, ultrafast laser welding has been widely used in chip labs, microelectronic systems (MEMS), and micro-medical implantable devices, etc. The welding of the non-optical contact transparent materials has become a new challenge to promote the practical application of ultrafast laser welding, and the existing research mostly through spatially and/or temporally shaping the laser under the single scanning. In this context, we adopt a multi-scan picosecond laser welding method to weld the non-optical soda lime glass that has a gap up to ∼5 μm. A welding region of 12 × 1 mm2 and a welding strength of 6.5 MPa is achieved by using a 1064 nm, 13 ps, 50 kHz picosecond laser. In addition, the effects of the scanning number (0–35), laser power (0–3.2 W), focus position (-113.4 µm- +18.9 µm) on the welding performance are systematically studied, while the intrinsic mechanism of multi-scan welding of the non-optical contact sample is also revealed. Finally, the optimal welding parameters of the multi-scan (scanning number 15, laser power 2.5 W, focus position −37.8 µm) is used in welding of cylinder samples with a radius of 12.7 mm and the results shows a well welding strength and sealing performance. The welding method proposed in this paper is simple and can provide a new technical solution for the practical application of ultrafast laser welding.