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http://dx.doi.org/10.6117/kmeps.2015.22.2.047

Effects of PCB Surface Finishes on in-situ Intermetallics Growth and Electromigration Characteristics of Sn-3.0Ag-0.5Cu Pb-free Solder Joints  

Kim, Sung-Hyuk (School of Materials Science and Engineering, Andong National University)
Park, Gyu-Tae (School of Materials Science and Engineering, Andong National University)
Lee, Byeong-Rok (School of Materials Science and Engineering, Andong National University)
Kim, Jae-Myeong (STATS ChipPAC Korea Ltd.)
Yoo, Sehoon (Korea Institute of Industrial Technology, Advanced Welding and Joining R&BD Group)
Park, Young-Bae (School of Materials Science and Engineering, Andong National University)
Publication Information
Journal of the Microelectronics and Packaging Society / v.22, no.2, 2015 , pp. 47-53 More about this Journal
Abstract
The effects of electroless nickel immersion gold (ENIG) and organic solderability preservative (OSP) surface finishes on the in-situ intermetallics reaction and the electromigration (EM) reliability of Sn-3.0Ag-0.5Cu (SAC305) solder bump were systematically investigated. After as-bonded, $(Cu,Ni)_6Sn_5$ intermetallic compound (IMC) was formed at the interface of the ENIG surface finish at solder top side, while at the OSP surface finish at solder bottom side,$ Cu_6Sn_5$ and $Cu_3Sn$ IMCs were formed. Mean time to failure on SAC305 solder bump at $130^{\circ}C$ with a current density of $5.0{\times}10^3A/cm^2$ was 78.7 hrs. EM open failure was observed at bottom OSP surface finish by fast consumption of Cu atoms when electrons flow from bottom Cu substrate to solder. In-situ scanning electron microscope analysis showed that IMC growth rate of ENIG surface finish was much lower than that of the OSP surface finish. Therefore, EM reliability of ENIG surface finish was higher than that of OSP surface finish due to its superior barrier stability to IMC reaction.
Keywords
Pb-free solder; electromigration; ENIG; OSP; Sn-Ag-Cu; in-situ;
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Times Cited By KSCI : 7  (Citation Analysis)
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