Effects of Cu orientation on the microstructure of Sn-2Ag-2.5Zn /Cu interface

The effects of Cu orientation on the microstructure and growth of IMCs in Sn-2Ag-2.5Zn /Cu solder joints were studied. After reflowing at 250 °C for 10 s, the continuous scallop-like IMCs Cu₆Sn₅ in Sn-2Ag-2.5Zn /polycrystalline Cu solder joint were more flat and thinner than that on (110), (111) oriented Cu substrates. The grain size of IMC on single crystal Cu substrates was larger than that of IMC on polycrystalline Cu. While during aging time, the growth rate of IMC on polycrystalline Cu substrates was slower, compared with that on (110), (111) oriented Cu substrates, and the thickness of IMC on (110), (111) oriented Cu substrates showed no visible differences, It was observed that the thickness of IMC was proportional to the square of the time in aging process.