Title :
Failure Mechanism of Sn-Ag-Cu Flip-chip Solder Joints with Different Cu Weight Contents Under Comparatively Low Current Stressing
Author :
Lai, Yi-Shao ; Chiu, Ying-Ta
Author_Institution :
Adv. Semicond. Eng. Inc., Kaohsiung
fDate :
May 29 2007-June 1 2007
Abstract :
This work presents electromigration reliability and patterns of Sn-3Ag-0.5Cu and Sn-3Ag-1.5Cu/Sn-3Ag-0.5Cu composite flip-chip solder joints with Ti/Ni(V)/Cu under bump metallurgy (UBM), bonded on Au/Ni/Cu substrate pads. The solder joints were subjected to an average current density of 5 kA/cm2 under an ambient temperature of 150degC. Under the situation when electron charges flow from the UBM towards the substrate, Sn diffuses from the Cu-Ni-Sn intermetallic compound (IMC) developed around the UBM towards the UBM, and eventually causes the Ni(V) layer to deform. Electromigration reliability of Sn-3Ag-1.5Cu/ Sn-3Ag-0.5Cu composite flip-chip solder joints was found to be better than that of Sn-3Ag-0.5Cu solder joints. A failure mechanism is proposed according to the Cu weight contents of these two solder joints.
Keywords :
copper alloys; current density; diffusion; electromigration; failure analysis; flip-chip devices; integrated circuit metallisation; integrated circuit reliability; nickel alloys; silver alloys; solders; substrates; tin alloys; CuNiSn; IMC; SnAgCu; UBM; current density; deformation; diffusion; electromigration reliability; electron charges; failure mechanism; flip-chip solder joints; intermetallic compound; substrate pad bonding; under bump metallurgy; Bonding; Current density; Electromigration; Electrons; Failure analysis; Flip chip solder joints; Gold; Soldering; Temperature; Tin;
Conference_Titel :
Electronic Components and Technology Conference, 2007. ECTC '07. Proceedings. 57th
Conference_Location :
Reno, NV
Print_ISBN :
1-4244-0985-3
Electronic_ISBN :
0569-5503
DOI :
10.1109/ECTC.2007.373988
