Abstract: Disclosed is a tin-based electroplating solution for forming solder bumps of a flip chip package. The tin-based electroplating solution includes tin methanesulfonate, silver methanesulfonate, methanesulfonic acid, a fluorinated surfactant, an aromatic polyoxyalkylene ether, and water. Also disclosed is a method for forming solder bumps by using the electroplating solution. The method includes (1) electroplating a silicon wafer having a protective layer through which an electrode pad is exposed and an under bump metallurgy (UBM) layer with a copper or copper/nickel plating solution to form copper or copper/nickel pillars on the under bump metallurgy layer and (2) electroplating the pillars with the tin-based electroplating solution to form solder bumps.