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