Welding of dissimilar materials, particularly copper and aluminum alloys, has gained considerable industrial interest in many different electric and electronic fields, such as the production of lithium-ion batteries for automotive applications. The differences in physical and chemical properties of these materials make fusion welding processes difficult to apply due to the formation of hard and brittle intermetallic compounds that impair both mechanical and electrical performance. In this paper, the effect of spot diameter on dissimilar laser autogenous lap-welding of copper and aluminum was studied. Experiments were conducted using a mid-power fiber laser source equipped with a galvo scanner and two different focal lengths to obtain two different spot diameters. The results showed that a smaller spot diameter promoted the formation of sound weld beads with better control of penetration depth, reduced mixing of the base metals and lower laser power requirements. By selecting the correct process parameters, good mechanical properties and low contact resistance could be obtained with both focal lengths. SEM-EDX analysis confirmed that a smaller spot diameter minimized the formation of copper rich phases in the weld bead.

异种材料的焊接，尤其是铜和铝合金，在许多不同的电气和电子领域获得了相当大的工业兴趣，例如用于汽车应用的锂离子电池的生产。这些材料的物理和化学性质的差异使得熔焊工艺难以应用，因为会形成硬而脆的金属间化合物，从而损害机械和电气性能。本文研究了光斑直径对异种激光铜铝搭接焊的影响。使用配备振镜扫描仪和两种不同焦距的中功率光纤激光源进行实验，以获得两种不同的光斑直径。结果表明，较小的光斑直径促进了良好焊道的形成，更好地控制了熔深，减少了母材的混合，降低了对激光功率的要求。通过选择正确的工艺参数，两种焦距均可获得良好的机械性能和低接触电阻。SEM-EDX 分析证实，较小的光斑直径最大限度地减少了焊道中富铜相的形成。