Reactive wetting of solders on Cu and Cu6Sn5/Cu3Sn/Cu substrates using wetting balance

Using a wetting balance technique, it was found that for Sn-rich solders, the wetting time was smaller on Cu than that on Cu6Sn5/Cu3Sn/Cu, and the wetting forces were not markedly different for the two kinds of substrates. However, for high-Pb solders on Cu6Sn5/Cu3Sn/Cu, the wetting time became smaller while the wetting force became larger. The phase transformation from Cu6Sn5 to Cu3Sn was detected for 5SnPb solder wetting on Cu6Sn5/Cu3Sn/Cu substrate. Compared with the surface roughness, the energy released from interfacial reaction played a dominant role in the wetting occurrence and dynamic velocity.