Growth behavior of Cu6Sn5 grains formed at an Sn3.5Ag/Cu interface

The growth behavior of Cu6Sn5 grains formed at an Sn3.5Ag/Cu interface was investigated. During soldering, Cu6Sn5 grains formed at the interface, showing a flattened ovoid shape. During solidification, Cu precipitated from molten solder in the form of Cu6Sn5, forming faceted surfaces on existing interfacial grains. The interfacial Cu6Sn5 morphology was unrelated to its crystal orientation, which was primarily dependent on reaction temperature. A reaction temperature of 240 °C led to an increase in (002) growth and a decrease in (101) growth with time. However, the (002) plane peak was not detected in the interfacial grains formed at a higher reaction temperature (280 °C).