|About this Abstract
||2016 TMS Annual Meeting & Exhibition
||Emerging Interconnect and Pb-free Materials for Advanced Packaging Technology
||Fracture Reliability Concern of (Au,Ni)Sn4 Phase in 3D IC Microbumps Using ENIG Surface Finishing
||Yingxia Liu, Yi-Ting Chen, Sam Gu, Dong Wook Kim, King-Ning Tu
|On-Site Speaker (Planned)
Due to the dimensional shrinkage of solder joints in mobile microelectronic devices, Au surface finishing on Ni layer in solder joints can lead to the replacement of β-Sn by (Au,Ni)Sn4 phase in microbumps. A thorough crack in (Au,Ni)Sn4 is found after the sample being annealed at 150 oC for 1000 h. Phase transformation of (Au,Ni)Sn4 to Ni3Sn4 and AuNi2Sn4 is observed after the annealing. This transformation will lead to - 10.3% volume shrinkage. Volume shrinkage may result in tensile stress and become the reason for a thorough crack formation. Also, Kirkendall voids have been found at the interface between Ni3Sn4 and Ni layer. Marker movement indicates there is a dominant Ni diffusing flux. It is because the phase transformation of (Au,Ni)Sn4 to AuNi2Sn4, which results in an extra flux of Ni diffusing out of Ni layer. Amorphous Ni(P) won’t have Kirkendall voids at the interface between Ni(P) and Ni3Sn4. Both the tensile stress in microbumps and the Kirkendall voids will become mechanical reliability concerns in 3D IC microbump technology.
||Planned: A print-only volume