A solder alloy making {HEAD ~ layer} for preventing dissolving and {TAIL ~ diffusion} of tin into tin based lead free solder is thinly formed on a UBM layer 
A solder alloy making { HEAD ~ layer } for preventing dissolving and { TAIL ~ diffusion } of tin into tin based lead free solder is thinly formed on a UBM layer
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH