Nd:YAG laser surface treatment of copper to improve the wettability of Sn3.5Ag solder on copper

Nd:YAG laser surface treatment of copper was found to affect the wettability characteristics of SnAg eutectic lead-free solder on copper. The basic process phenomenon was investigated and the microstructure and wetting characteristics of the solder was determined using optical microscopy and X-ray diffraction techniques. To analyze mechanism of the microstructure changes in the surface layer after laser treatment, a finite element modeling (FEM) model was proposed, the simulated temperature distribution and temperature gradient distribution in the surface layer were presented. The results showed that laser surface treatment can improve the wetting characteristics of the Sn3.5Ag solder on the copper and the mechanism was discussed in detail. The work has shown clearly that laser irradiation can be used to improve the wettability of Sn3.5Ag solder on copper.