Title :
Electromigration failure mechanism of Sn96.5Ag3.5 flip-chip solder bumps
Author :
Shao, T.L. ; Chen, I.H. ; Chih Chen
Author_Institution :
Dept. of Material Sci. & Eng., Nat. Chiao-Tung Univ., Hsin-Chu, Taiwan
Abstract :
The electromigration-induced failure of SnAg3.5 flip chip solder bumps was investigated at the current density of 1 × 104 A/cm2 at 150°C, and they failed after 22 hours of current stressing. Failure was found to be on anode/chip side, and large (Cu,Ni)6Sn5 intermetallic compounds (IMCs) were observed on the interface of the UBM and the solder bump. A novel electromigration failure mechanism is proposed. Nickel atoms were migrated by electron flow from substrate side to chip side to form (Cu,Ni)6Sn5 IMCs. The volume expansion due to the IMC formation may induce local high stress around the UBM and fail the contact of the anode/chip side.
Keywords :
electromigration; flip-chip devices; reflow soldering; silver alloys; solders; tin alloys; (CuNi)6Sn5; 150 C; Cu; SnAg; current density; current stressing; electromigration-induced failure; electron flow; environmental concerns; failure mechanism; flip chip solder bumps; large intermetallic compounds; volume expansion; Anodes; Current density; Electromigration; Electrons; Failure analysis; Flip chip; Intermetallic; Nickel; Stress; Tin;
Conference_Titel :
Electronic Components and Technology Conference, 2004. Proceedings. 54th
Print_ISBN :
0-7803-8365-6
DOI :
10.1109/ECTC.2004.1319458
