Solder bumps are fabricated by plating a first solder layer on an underbump metallurgy, plating a second solder layer having higher melting point than the first solder layer on the first solder layer and plating a third solder layer having lower melting point than the second solder layer on the second...http://www.google.es/patents/US6492197?utm_source=gb-gplus-sharePatente US6492197 - Trilayer/bilayer solder bumps and fabrication methods therefor
Trilayer/bilayer solder bumps and fabrication methods therefor
