Study of 100 kHz femtosecond laser continuous scanning welding and spot welding of glass and aluminium film

In this paper, we studied the femtosecond laser welding of soda–lime–silicate glass and a pure aluminium film by employing a 100 kHz femtosecond laser. The morphology of the whole welding region is the same as that of the glass. The sizes of the defects in the welding regions must be very small, so that it looks like that the welding region integrates seamlessly with the glass. However, the real profile of the welding region can be still plotted after analyzing the SEM-EDS data and the Raman data. The welding region can be divided into three major parts: the area formed from the solidifying plasma of aluminium, from the solidifying mixed plasma of two materials, and where the silicate networks are partly destroyed, respectively. This means that the material properties in the welding region gradually transform from ductile to brittle towards the beam. We also studied two types of welding, continuous scanning welding and spot welding, and the lap shear strengths are compared in the different total areas of the welds. The data show that both types of the laser welding can provide strong strength. We attribute the high strength to the density of the welding region which results from a step welding dynamics caused by a relatively low repetition rate and a relatively high intensity.