Electromigration of SnPb flip chip solder bumps with thick Ni/Cu under bump metallization

• Main Authors: CHEN CHUN-HONG, 陳俊宏
• Other Authors: CHEN CHIH
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/01929528302074238570

碩士 === 國立交通大學 === 材料科學與工程系所 === 94 === Flip Chip Technology is one of the most important packaging methods for high current density IC device. While current density applied increased, solder joint has become a critical issue on device reliability. Concerning electromigration, the device design rule makes each solder bump need to carry 0.2A to 0.5A, and the current density will meet 103~104A/cm2. There is still little study on solder EM with thick UBM structure (Ni/Cu). In this study, thick UBM (electroplating Ni 3µm/Cu 5µm) with SnPb solder (Sn80/Pb20) with 104~105 A/cm2 at elevated 150℃ is investigated. The solder height is about 70µm, and electroless-Ni 3µm as barrier layer at board side. Failure mechanism would be proposed that solder dissolution accelerates continuous IMC formation, and continues redistribution between Sn and Pb was found. The findings in TTF, that Sn80Pb20 solder joints with thick UBM is significant longer than e-SnPb with thin film UBM. In addition, the temperature and current distribution due to current applied was corrected by Infrared Microscopy and simulation to prove Black’s equation’s Q=2.1eV and n=6.2 .