Kirkendall voids formation in the reaction between Ni-doped SnAg lead-free solders and different Cu substrates

Interfacial reactions of fine-pitch Cu/Sn–3.5Ag pillar joints on Cu/Zn and Cu/Ni under bump metallurgies

“…The thickness of the Cu 6 Sn 5 layer in the case of the Cu/Zn UBM sample was similar to that in the case of the Cu UBM sample. In case of the Cu/Ni UBM sample, (Cu 1Àx Ni x ) 6 Sn 5 was also formed after the flip-chip bonding; this was in keeping with previous reports [10,18,19]. The thickness of the (Cu 1Àx Ni x ) 6 Sn 5 layer in the case of the Cu/Ni UBM sample was higher than those for the Cu and Cu/Zn UBM samples.…”

Effects of current density on the formation and microstructure of Sn–9Zn, Sn–8Zn–3Bi and Sn–3Ag–0.5Cu solder joints

“…It was explained in another research work that the dominant formation of Cu 6 Sn 5 IMC at the solderesubstrate interface after soldering was due to the lower activation energy for the growth of Cu 6 Sn 5 compared to that of Cu 3 Sn [30]. Besides, in this research work, it can be seen that Cu 6 Sn 5 IMC exhibited a scallop-type structure, which had also been reported in previous research works [28,31,32]. The formation of Cu 6 Sn 5 scallops was explained by the combination of kinetic processes of ripening and interfacial reaction [33].…”

Fundamental Study of the Intermixing of 95Pb-5Sn High-Lead Solder Bumps and 37Pb-63Sn Pre-Solder on Chip-Carrier Substrates

“…The layer between Cu 6 Sn 5 and Cu was very likely Cu 3 Sn, according to results found in similar studies. [10][11][12][13][14][15] Additional reflows did not change the interfacial reaction on the substrate side, and the results are omitted here for the sake of brevity. Additional reflow, however, did produce substantial change on the chip-side interface, as shown in Fig.…”