Interfacial bonding behavior with introduction of Sn-Zn-Bi paste to Sn-Ag-Cu ball grid array package during multiple reflows

Sn-8Zn-3Bi solder paste and Sn-3.2Ag-0.5Cu solder balls were reflowed simultaneously on Cu/Ni/Au metallized ball grid array (BGA) substrates to investigate the interfacial bonding behaviors for multiple reflow cycles at two different soldering temperature of 210 and 240 degrees C. The different intermetallic compounds that formed at the interface after one reflow cycle were respectively the island-shaped Ag-Au-Cu-Zn (near the. solder) compounds and the Ni-Sn-Cu-Zn (near the metallized pad) compounds in 210 or 240 degrees C soldering systems. Layered Ag-Au-Cu-Zn, Ag5Zn8, and Ag-Zn-Sn compounds were also observed within the solder near the interface after single reflow cycle. After ten reflow cycles, the Ag-Au-Cu-Zn compounds significantly decomposed, while the Ag3Sn and Ni-Sn-Cu-Zn compounds coarsened obviously.