The advantages are manifold
PDF) UBM (Under Bump Metallization) study for Pb-free electroplating bumping: Interface reaction and electromigration
High Performance Electroless Nickel that's Lead and Cadmium-Free
UBM - Under Bump Metallization by
Interfacial Reaction and Bump Shear Property of Electroplated Sn-37Pb Solder Bump with Ni under Bump Metallization during Multiple Reflows
High Performance Electroless Nickel that's Lead and Cadmium-Free
Electroless UBM Formation Service|Special Site of JX Metals
Figure 7 from Mechanism of electromigration-induced failure in flip-chip solder joints with a 10-μm-thick Cu under-bump metallization
A study in flip-chip UBM/bump reliability with effects of SnPb solder composition - ScienceDirect
Interconnection in IC Assembly - ppt video online download
15544557.ppt
Interconnection in IC Assembly - ppt download