Patent ID: 7629246
Filing Date: 2009-12-08
Classification: B23K,H01L,H05K,Y02P

Abstract:
1. A method for forming a high-strength solder joint between a solder ball and a microelectronic circuit package that contains at least one contact pad at its interconnect face, said method comprising: providing at least one solder ball, said solder ball having a polymeric core surrounded by a metallic shell, containing copper (Cu), that in turn is surrounded by a layer of solder material, containing tin (Sn); positioning the at least one solder ball atop the at least one contact pad of the circuit package, said contact pad containing copper (Cu); and reflowing said solder material between the solder ball and the corresponding contact pad for a preselected temperature range and a preselected time range such that an intermetallic layer, composed of Cu