Title :
Electromigration induced failure in SnAg3.8Cu0.7 solder joints for flip chip technology
Author :
Hsu, Y.C. ; Shao, T.L. ; Chen, Chih
Author_Institution :
Dept. of Material Sci. & Eng., Nat. Chiao Tung Univ., Hsinchu, Taiwan
Abstract :
Electromigration of SnAg3.8Cu0.7 solder was investigated in flip chip solder bump. An under-bump metallization (UBM) of Cr/Cr-Cu/Cu tri-layer was deposited on the chip side and electroless Cu/Ni/Au pad was deposited on the BT board side. Electromigration damage was observed under the current density of 2×104 A/cm2 at 100°C. Voids were found at cathode side and crack was observed at solder/thin film UBM interface after current stressing, and the bump failed after 168-hour stressing. Copper atoms were found to move in the direction of electron flow. Intermetallic compounds of Cu-Sn and Ni-Cu-Sn were also observed to spread into the solder bump due to current stressing.
Keywords :
copper alloys; electromigration; failure analysis; flip-chip devices; metallisation; silver alloys; soldering; tin alloys; 100 degC; Cr-CrCu-Cu; Cr/Cr-Cu/Cu trilayer; Cu-Ni-Au; Cu/Ni/Au electroless pad; SnAg3.8Cu0.7; SnAg3.8Cu0.7 solder joint; crack; current stress; electromigration induced failure; flip-chip solder bump; intermetallic compound formation; solder/thin film UBM interface; under-bump metallization; void; Cathodes; Chromium; Copper; Current density; Electromigration; Electrons; Flip chip; Gold; Metallization; Transistors;
Conference_Titel :
Electronic Materials and Packaging, 2002. Proceedings of the 4th International Symposium on
Print_ISBN :
0-7803-7682-X
DOI :
10.1109/EMAP.2002.1188852
