A combined solder alloy layer composed of {TAIL ~ a combination} of intermetallic compounds, one of tin and {HEAD ~ the solder alloy} making layer, and one of tin and the UBM layer, is formed by heating and melting 
A combined solder alloy layer composed of { TAIL ~ a combination } of intermetallic compounds , one of tin and { HEAD ~ the solder alloy } making layer , and one of tin and the UBM layer , is formed by heating and melting
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH