Key words: Ag-Cu-Sn ternary diffusion diffractogram electron probe
Ag-Cu-Sn medium temperature solder is widely used in the field of electronic packaging due to its excellent temperature resistance, creep resistance and corrosion resistance. However, due to its inherent brittleness, the preparation is difficult and the yield is low, and Ag-Cu- is established. The Sn phase diagram plays an important guiding role in the design and preparation of Ag-Cu-Sn solder.
In this paper, the phase equilibrium relationship of Ag-Cu-Sn ternary diffusion couple at 450 °C and its composition were determined by scanning electron microscopy and electron probe micro-area composition analysis method. The 450 °C was established at 450 °C. A ternary isothermal section of Ag-Cu-Sn-rich Ag-Cu region.
The results show that there are four binary compounds Cu41Sn11, Cu3Sn, Ag5Sn and Ag3Sn in the Ag-Cu-Sn ternary diffusion couple. No ternary compounds are found, and the solid solubility of Cu in Ag5Sn and Ag in Cu41Sn11 and Cu3Sn respectively It is 4.89 at%, 4.63 at%, and 7.89 at%. It is found that there are three three-phase regions in the Ag-Cu-Sn ternary Ag-rich region at 450 °C: Ag+Cu41Sn11+Cu, Ag+Cu41Sn11+Cu3Sn, Ag5Sn+Ag+Cu3Sn.
The determination of the Ag-Cu-Sn ternary isothermal section by the diffusion couple technique helps to determine the reliability of existing results and to add new data to the Ag-Cu-Sn phase equilibrium.