Title :
Influence of Cu columns on current crowding effect in electromigration in flip-chip solder joints
Author :
Liang, Y.C. ; Tsao, W.A. ; Yao, Da-Jeng ; Lai, Yi-Shao ; Chen, Chih
Author_Institution :
Dept. of Mater. Sci. & Eng., Nat. Chiao Tung Univ., Hsinchu, Taiwan
Abstract :
The electromigration in SnAg solder bumps with and without Cu column UBM have been investigated at 2.16×104 A/cm2 at 150°C. Different failure modes were observed for the two types of samples. When the SnAg solder bump with only Ni UBM was stressed by 2.16×104 A/cm2, open failure occurred in the bump that the direction of electron flow was from the chip side to the board side. However, the crack formed along the interface between the IMC Cu6Sn5 and the solder on the substrate side in the Sn-3.0Ag-0.5Cu solder bump with Cu column UBM. A three-dimensional simulation of the current density distribution was performed to provide a better understanding of the current crowding behavior in the solder bump. The current crowding effect was found to account for the failure in the chip/substrate side.
Keywords :
copper alloys; electromigration; flip-chip devices; silver alloys; solders; tin alloys; IMC; SnAgCu; column UBM; current crowding effect; electromigration; flip-chip solder joints; solder bumps; temperature 150 degC; three-dimensional simulation; Copper; Current density; Electromigration; Nickel; Proximity effects; Soldering; Substrates;
Conference_Titel :
Electronics Packaging Technology Conference (EPTC), 2011 IEEE 13th
Conference_Location :
Singapore
Print_ISBN :
978-1-4577-1983-7
Electronic_ISBN :
978-1-4577-1981-3
DOI :
10.1109/EPTC.2011.6184535
