Laser induced forward transfer of brittle Cu3Sn thin film

Abstract Cu3Sn intermetallic compound as an interconnecting material has great prospect in power electronic device applications due to its high melting temperature. However, the intermetallic compound is essentially brittle, and hard to be transferred. In this study, Cu3Sn thin films have been successfully transferred by means of laser-induced forward transfer (LIFT) process with millisecond pulse length. The morphology of LIFT-processed Cu3Sn thin film was investigated by optical microscopy and Atomic Force Microscopy (AFM). The optimized transfer process parameters were 0.3 ms laser irradiation, 8001100 W laser power and 14 mm defocusing amount. Under the optimized conditions, the deposition pattern of Cu3Sn thin films were complete and uniform. The transfer mechanism was that the solid Cu3Sn films have been pushed and transferred by the gasified part Cu3Sn near the interface of the donor substrate during the LIFT process.