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