Dissimilar materials spot welding between A5052 and PET (Polyethylene Terephthalate) has been carried out by using pulse YAG laser. Weldable conditions were obtained for PET/A5052 joint. Tensile-Shear test was conducted to evaluate strength of the joint. The maximum failure load in tensile-shear test was obtained for the joint welded with laser irradiation condition of 300V-20msec (65.5J). PET was observed in molten zone of A5052 in cross section of the welded region. Welded area increased with increase in heat input. Strength of joint was calculated apparently by failure load and welded area. The strength was almost constant regardless increasing of heat input in higher heat input conditions. However, in lower heat input conditions, the strength was not constant. Molten pool shape of A5052 changed with laser irradiation condition and that was not only depending on heat input. The difference in molten pool shape might affect on strength of the joint.
