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

Volume

1

fYear

2004

fDate

1-4 June 2004

Firstpage

979

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;

fLanguage

English

Publisher

ieee

Conference_Titel

Electronic Components and Technology Conference, 2004. Proceedings. 54th

Print_ISBN

0-7803-8365-6

Type

conf

DOI

10.1109/ECTC.2004.1319458

Filename

1319458