Cu-Ni-Sn: A Key System for Lead-Free Soldering

• Published in: Journal of electronic materials 2009, Vol.38 (1), p.10-24
• Main Authors: Schmetterer, C., Flandorfer, H., Luef, Ch, Kodentsov, A., Ipser, H.
• Format: Article
• Language: English
• Subjects: Alloys; Applied sciences; Brazing. Soldering; Characterization and Evaluation of Materials; Chemistry and Materials Science; Condensed matter: structure, mechanical and thermal properties; Copper; Cross-disciplinary physics: materials science; rheology; Electronics and Microelectronics; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Instrumentation; Joining, thermal cutting: metallurgical aspects; Lead free solders; Materials Science; Metals. Metallurgy; Nickel; Optical and Electronic Materials; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Phase diagrams of metals and alloys; Physics; Silver; Solid State Physics; Solubility, segregation, and mixing; phase separation; Tin
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-008-0522-4

Being the most complex constituent of the quaternary system Ag-Cu-Ni-Sn, the ternary system Cu-Ni-Sn is the key system for the investigation of the interactions of Ag-Cu-Sn solder alloys with Ni as a contact material. Although this system has been thoroughly studied in the literature, there are still many uncertainties left. In the present work, a study of the phase equilibria in four isothermal sections at 220, 400, 500, and 700°C of the Cu-Ni-Sn system was carried out following a comprehensive literature study. The methods employed were x-ray diffraction (XRD), metallography, and scanning electron microscopy including electron probe microanalysis. The ternary solubilities of the Ni 3 Sn 2 -Cu 6 Sn 5 and Ni 3 Sn-Cu 3 Sn fields were characterized in detail. So far no continuous solubility between the respective phases has been found. At 25 at.% Sn the existence of two ternary compounds formed from the BiF 3 -type (Cu,Ni) 3 Sn phase and reported in literature could be confirmed. On the other hand, our results differ significantly from the very recent literature related to lead-free soldering.