BLR Drop Test Study for FCCSP Package with OSP/Cu Solder Pad finish

Over the past decade, flip-chip technology has revolutionized the way we think about semiconductor components and integrated circuits. This sophisticated manufacturing process enables high-performance and cost-effective products to be manufactured in smaller sizes. Especially for commercial and industrial application, board level reliability drop test was required. In this paper, BLR drop test were studied with different solder alloys for FCCSP package with OSP (Organic Solderability Preservative) /Cu solder pad finish. In terms of paper reference, Ni doped solder ball can improve BLR drop test performance due to relived compression stress mechanism. Especially, both Ni doped solder alloys and no Ni doped solder alloys were included into this evaluation. In terms of evaluation, no Ni doped solder alloy Sn3.5Ag cannot pass BLR drop test even it can still meet process requirements including solder ball shear strength test at TO and after 3x reflow and high speed solder ball shear strength test. The IMC measurement showed rapid growth after 3x reflow and not continuous for IMC layer. As for two types of Ni doped solder alloy, they can both pass BLR drop test and process data can also meet requirements. The 1 st drop failure is at 58drops for Sn3.5Ag (Ni) and 72drops for SAC305 (Ni). IMC check with Ni doped solder ball did show that Ni addition into solder ball can restrain the formation of Cu3 Sn IMC and restrained the growth of Cu6Sn5 IMC which can finally improve BLR drop test performance. At the same time, BLR TC test was also passed.