Study of a Low Cost Reballing of BGA Method with Lead-Free Solder Paste

Abstract

Due to environmental consciousness and legislative regulations, lead-free solders have been replaced most of the conventional lead-containing solders in microelectronic industry. In response to the concern over Pb used in electronic products and manufacturing electronics, much work is ongoing to find new parameters for re-balling process. This paper describes a low cost reballing method with lead free solder paste on BGA (Ball Grid Array) packages. It was used a lead free solder paste with composition Sn 96,5%, Ag 3,0% and Cu 0,5% and the reflow technology. The results obtained were compared with the conventional reballing method. The solder properties such as wetting characteristics as well as the amount of solder paste deposited by dispenser onto the substrate bond pads influenced on the formation of the bumps. By controlling the volume of solder paste deposited and the parameters used during the reflow step it was possible to obtain bumps liked semi spherical format that can be used to replace the solder balls on the conventional rework of BGA.