Effect of small Sn-3.5Ag-0.5Cu additions on the structure and properties of Sn-9Zn solder in ball grid array packages

摘要

Sn-9Zn with various additions of Sn-3.5Ag-0.5Cu powder was prepared by mechanically dispersing different weight percentages (1, 3, 5 and 7) of Sn-Ag-Cu powder into Sn-9Zn solder paste. In the Sn-Zn solder, scallop-shaped AuZn3 intermetallic compound was found at the interfaces. On the other hand, in the Sn-3.5Ag-0.5Cu content solders, an additional ?`-AgZn3 intermetallic compound layer was found to be well adhered on the top surface of the AuZn3 layer and the ?`-AgZn3 layer thickness increased with the number of reflow cycles. In add