Laser Irradiation on Tin Electroplating and Whisker Suppressibility

Tin electroplating with its excellent solderability and low cost performance is garnering attention as a lead-free technology. However, tin electroplated film is plagued with the issue of whisker formation. In this research, in order to suppress the whisker formation, the effect of laser irradiation on tin electroplated film onto a phosphor bronze substrate was studied by scanning electron microscopy and focused ion beam microscopy. Whiskers and nodules were generated on the surface of the tin electroplated film for a short time after electroplating. However, laser irradiated specimens showed no whiskers as well as nodules. This whisker suppression is attributable to the formation of thinly uniform intermetallic compound layer. Moreover, the solderability of the laser irradiated specimen was superior to that of the reflow specimen. These results demonstrated the effectiveness of laser treatment.