Comparison of Cu-Sn Compound Formation Between Snag and Pure Sn Solder Bumps by EBSD

Anisotropic behavior of Sn based solder during electromigration has been studied by many researchers, and it is very important to control the microstructure for more reliable bump joints[1]. Here, we prepared various SnAg bumps with different Ag concentrations including pure Sn[2]. Unary electroplating has various advantages such as easy handling bath, negligible bump composition and maintaining equipment with securing about environmental health and safety issue.
Figure 1 shows our preliminary experiments for the cross-sectional EBSD and EDS measurement of Cu pillar with pure Sn bump, and it is reflowed at 235°C for 6 min. In this study, we will report comparison of Sn microstructures according to various Ag inclusions by using cross-sectional EBSD(electron backscattered diffraction) analysis and EDS(energy dispersive spectroscopy) measurement. We carried out multiple reflows at various atmosphere how this impact IMC(intermetallic compound) growth along with microstructures. Through this crystallographic aspect approach, we will present optimum condition for resistance of electro migration and void formation.

[1] Yiwei Wang, Kuan H. Lu, Vikas Gupta, Leon Stiborek, Dwayne Shirley, Seung-Hyun Chae, Jay Im, Paul S. Ho, J. Mater. Res., 27, 1131 (2008)

[2] Ui-Hyoung Lee, Moongi Cho, Woojin Choi, Ha-Young You, Jinho Choi and Jaihyung Won, 224^th ECS meeting, San Francisco, Oct. (2013)