123697.fig.0011a
(a) t < 30 s
123697.fig.0011b
(b) 30 s < t < 180 s
123697.fig.0011c
(c) 180 s < t < 600 s
Figure 11: Growth mechanism of Cu-Sn IMCs at various reflow times: (a) formation of scallop Cu6Sn5 at the SAC305/Cu interfacial region, (b) appearance of Cu3Sn between the Cu6Sn5/Cu interface, and (c) increase in both Cu-Sn IMCs thicknesses with increasing reflow times.