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