Application of electron backscatter diffraction to the study on orientation distribution of intermetallic compounds at heterogeneous interfaces (Sn/Ag and Sn/Cu)

Abstract

In the current study, the orientation distribution and formation mechanism of intermetallic compounds (IMCs) at heterogeneous interfaces (Sn/Ag or Sn/Cu) were investigated by using electron backscatter diffraction (EBSD) method. The EBSD orientation maps have revealed that some special orientation relationships exist not only at the interfaces between the faceted IMC and (001) or (111) single crystal substrates but also at the interfaces of the scalloplike IMC/(011) single crystal substrate, which are attributed to the low misfit between the IMC and the substrates. However, only part of special orientation relationships can be obtained by using the pole figure when a large number of IMC grains were considered. The reason is that the single crystal substrate can supply more immobile atoms for these special orientated IMC cluster. With increasing the reflowing or aging time, the orientation relationship has no obvious change between the IMC and the single crystal substrates. Meanwhile, it is found that the determinative factor controlling the IMC morphology should include two kinds of interfacial energies at the interfaces of IMC/solder and IMC/substrate. The variations in the interfacial energies would induce the transformation of the IMC morphology. These experimental results would be helpful for better understanding on the formation mechanisms of IMCs at the interfaces of Sn/crystals and promoting the wide application of EBSD to study the orientation relationships at other heterogeneous interfaces.