What is the composition of the lead free (PbF) solder bump and underbump (UBM) metals for EPC die?

Designing with GaN FETs and ICs Assembly and Layout
1

What is the composition of the lead free (PbF) solder bump and underbump (UBM) metals for EPC die?

2

The materials declarations will provide the specific composition for each device. Below are two standard compositions: