Journal of Welding and Joining

9: Journal of KWJS. 2013;31(3):4-10. Published online June 30, 2013.
DOI: https://doi.org/10.5781/KWJS.2013.31.3.4; Study on Joint of Micro Solder Bump for Application of Flexible Electronics; Yong-Ho Ko, Min-Su Kim, Taek-Soo Kim, Jung-Hwan Bang, Chang-Woo Lee; Corresponding author: Chang-Woo Lee ,Email: cwlee@kitech.re.kr

Abstract: In electronic industry, the trend of future electronics will be flexible, bendable, wearable electronics. Until now, there is few study on bonding technology and reliability of bonding joint between chip with micro solder bump and flexible substrate. In this study, we investigated joint properties of Si chip with eutectic Sn-58Bi solder bump on Cu pillar bump bonded on flexible substrate finished with ENIG by flip chip process. After flip chip bonding, we observed microstructure of bump joint by SEM and then evaluated properties of bump joint by die shear test, thermal shock test, and bending test. After thermal shock test, we observed that crack initiated between Cu6Sn5IMC and Sn-Bi solder and then propagated within Sn-Bi solder and/or interface between IMC and solder. On the other hands, We observed that fracture propated at interface between Ni3Sn4 IMC and solder and/or in solder matrix after bending test

Keywords :Bonding technology, Reliability, micro solder bump, Flexible substrate, Die shear test, Thermal shock test, Bending test