Characterisation of dissimilar joints in laser welding of steel–kovar, copper–steel and copper–aluminium

Joining of dissimilar materials is one of the challenging tasks facing modern manufacturers. Dissimilar joining technologies find applications in many sectors including microelectronics, medical, optoelectronics and microsystems. The tiny geometry of the joints and the different optical and thermal properties of the materials makes laser welding one of the most suitable production methods. This paper presents the results of an investigation into laser welding of dissimilar metals without filler materials using a 350 W pulsed Nd:YAG laser. The mixing behaviour of the materials in the fusion zone, the microstructure, the presence of defects, hardness and residual stress of the joints were all investigated.