Size effect on the interfacial reaction and IMC growth of Sn–3.0Ag–0.5Cu/Cu joints with the decreasing joint size to several tens of microns during reflowing soldering

摘要

In this article, Sn–3.0Ag–0.5Cu solder balls including 30, 60, 100, 200, 400 and 600 μm in diameter were reflowed on Cu substrates to obtain Sn–3.0Ag–0.5Cu/Cu joints. These joints corresponding to the three different solder joints in three-dimensional integrated circuit integration were used to study the size (volume) effect of solder balls on the interfacial reaction. Results indicate that the average grain size of intermetallic compound (IMC) is non-monotonic with the increasing diameter of solder balls, i.e., interfacial IMC grain size ascends as solder ball diameter increases from 30 to 200 μm, and then decreases with the increasing solder balls from 200 to 600 μm in diameter. Meanwhile, the grain boundary migration and Oswald ripening are the major IMC grain coarsening mechanisms for solder joints with solder balls smaller than 100 μm and larger than 200 μm in diameter, respectively.