ELECTROPLATING OF LEAD-FREE BUMPS ON 300mm WAFERS FOR WLP APPLICATIONSAuthors: N. Saito, R. Kiumi, F. Kuriyama, and K. Kamimura
Company: Precision Machinery Company, Ebara Corporation
Date Published: 11/3/2005 Conference: IWLPC (Wafer-Level Packaging)
Also, when comparing with Sn-Pb solder, the larger electric potential difference between the components of lead-free alloys will make the composition ratio of plated alloys unstable in electroplating. There are a lot of reports on lead-free bumping processes, and then there is little report on research of lead-free bump plating mass-production. This paper describes the control of the compositions in the Sn-Ag alloy plating production line for 300mm wafers.
The composition control of lead-free solder bumping has been primarily experienced on 300mm wafer mass-production conditions for flip chip or wafer level packaging. For fabrication of Sn-1.5-3.5wt%Ag lead-free bumps on 300mm wafers, our study verified over 1000 wafers could be electroplated without adjustment of plating solution by means of UFP-300 plating machine. The results of this study show that an advanced electroplating process can be successfully applied to the fabrication of the Sn-Ag lead-free solder bumps on mass production.
Key Words: Sn-Ag bump, lead-free solder bumping, electroplating, flip chip packaging
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