Inhibiting the consumption of Cu during multiple reflows of Pb-free solder on Cu

An effective approach to inhibiting the consumption of Cu during multiple reflows of SnAg2.3 solder on Cu is reported. By depositing a very thin layer of solder on Cu, followed by a 10-min reflow, the scallop-type morphology of interfacial Cu6Sn5 intermetallic compounds (IMC) became flat, and the channels between them closed up. When additional solder was deposited on the sample and reflowed again, the consumption of Cu as well as the growth the IMC was retarded.