Laser welding of dissimilar copper and aluminum sheets by shaping the laser pulses

Dissimilar metal joining of thin copper and aluminum sheets is very important in the battery connections. The main problem while joining this dissimilar combination is formation of brittle intermetallic phases that degrade the electrical and mechanical properties of the joint. For joining copper and aluminum sheet with laser, very high intensity in the range of 10^7 W/cm^2 is required. Intermixture of copper and aluminum is vital for joint ductility. In this paper, the effect of combined oscillation and shaping of the laser pulses on the overlap welding of copper-aluminum is studied. Precise control of intermixing can be achieved by modifying the laser pulse i.e. the percentage of power with respect to the pulse time. Investigation on different pulse shapes with ramp up and ramp down profile is conducted by cross-section and microstructural analysis.