DocumentCode :
2732571
Title :
A new Ni-Zn under bump metallurgy for Pb-free solder bump flip chip application
Author :
Cho, Hae-Young ; Kim, Tae-Jin ; Kim, Young Min ; Kim, Sun-Chul ; Park, Jin-Young ; Kim, Young-Ho
Author_Institution :
Div. of Mater. Sci. & Eng., Hanyang Univ., Seoul, South Korea
fYear :
2010
fDate :
1-4 June 2010
Firstpage :
151
Lastpage :
155
Abstract :
We developed an Au/Ni-Zn/Ti under bump metallurgy (UBM) for Pb-free solders. Au/Ni-Zn/Ti and Au/Ni/Ti UBM stacks were deposited on SiO2/Si wafer using conventional magnetron sputtering and Sn solder was electroplated on UBM stacks. Then, Sn solder on UBM were reflowed at 260°C for 15 s and aged at 150°C up to 1000 h. The measurement of film stress using a curvature method showed Ni-Zn films having the very low tensile stress could be obtained by controlling the Ar pressure. Ni3Sn4 intermetallic compound (IMC) was formed on both Ni-Zn UBM and Ni UBM after reflow and IMC thickness increased with aging time. Other IMCs besides Ni3Sn4 were not observed after aging. IMC growth of Ni-Zn UBM was slower than that of Ni. UBM consumption rate of Ni-Zn UBM was also lower than that of Ni UBM. These beneficial results were ascribed to the effect of Zn, which played a role of interdiffusion barrier between Sn and Ni. Our results revealed that Ni-Zn layer is a promising UBM for Pb free solders.
Keywords :
Aging; Flip chip; Gold; Pressure control; Pressure measurement; Sputtering; Stress control; Stress measurement; Tensile stress; Tin;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Electronic Components and Technology Conference (ECTC), 2010 Proceedings 60th
Conference_Location :
Las Vegas, NV, USA
ISSN :
0569-5503
Print_ISBN :
978-1-4244-6410-4
Electronic_ISBN :
0569-5503
Type :
conf
DOI :
10.1109/ECTC.2010.5490894
Filename :
5490894
Link To Document :
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