Research and development status of laser micro-welding of aluminum-copper dissimilar metals: A review

• Laser micro-welding of aluminum-copper dissimilar metals are reviewed entirely. • Laser micro-welding parameters of aluminum-copper dissimilar metals are discussed in detail. • Filler materials of laser micro-welding of aluminum-copper dissimilar metals are summarized. In the microelectronics industry, the high thermal and electrical conductivity of copper (Cu), the low volume density and the high efficiency of aluminum (Al) are extremely attractive. The unstable energy absorptivity and welding process, however, were caused by the high reflectivity and high thermal conductivity between Al and Cu. Meanwhile, brittle and complex intermetallic compounds (IMCs), such as Cu 2 Al and Cu 2 Al 2 and so on were formed easily when Cu and Al were fully mixed in the molten pool. In recent years, electronic packaging, battery components of new energy automobiles and other fields, laser micro-welding of Al-Cu dissimilar metals have been used widely. Laser micro-welding technology is superior to others micro-welding technology owning to its higher power density and unique controllability. In this paper, the laser micro-welding process of Al-Cu dissimilar metals and the effects of welding parameters including laser power, beam diameter, laser pulse and scanning mode and so on were discussed in detail. Filler materials and solder systems of laser micro-welding of Al-Cu dissimilar metals were summarized. The results showed that the tensile/shear strength of the good Al-Cu dissimilar joints was as strong as Al base metals, which was obtained when the IMCs layer was between 0.2 and 0.5 μm and the Cu content was less than 50%. In terms of the problems existing in laser micro-welding of Al-Cu dissimilar metals, some possible solutions and development tendency were reviewed.