To illustrate the interfacial reaction mechanism, the Sn-Zn[Sn-8.5Zn-0.5Ag- 0.01Al-0.1Ga (wt)] solder was reflowed on Cu substrate at 250 C for 15 s followed by immediate quench in liquid nitrogen. The frozen interfacial microstructure was investigated with high resolution transmission electron microscope. An amorphous double layer was formed at the interface which consists of a 5 nm pure Cu region and a Cu-Zn diffusion region. Nanocrystalline intermetallic compound (IMC) Cu5Zn8 were observed in the Cu-Zn diffusion region. These nanocrystalline IMCs are suggested to form via a homogeneous nucleation process.
All Science Journal Classification (ASJC) codes
- 物理與天文學 (全部)