Structural investigation in Cu-In-Sn alloys around 60 at.% Cu for Pb-free transient liquid phase bonding

SOMMADOSSI, S.; AURELIO, G.; CUELLO, G. J.

Gijón

Congreso; V Reunión de la Sociedad Española de Técnicas Neutrónicas; 2010

Sociedad Española de Técnicas Neutrónicas

The study of the Cu-Sn-In ternary system has acquired in recent years a great importance, due to new environmental regulations forcing to eliminate the use of Pb in bonding technologies for electronic devices, such as Transient Liquid Phase Bonding. There is a lack of basic information on this system regarding some intermetallic phases which grow in the bonding zone, particularly the so-called η-phase (Cu2In or Cu6Sn5) that exists in both the binary and the ternary phase. In this work, preliminary data are presented obtained for a series of six alloys with about 60 at.% Cu and with In and Sn contents ranging from 0 to 20 at.%, quenched from 300oC. The alloys were characterized using differential scanning calorimetry,electron probe microanalysis and neutron diffraction. Thermodiffraction experiments were performed and the temperature scans indicate a relation between the phase transitions observed in the calorimetry curves with structural modifications of the intermetallic phases. Neutron data also suggest the formation of superstructures in the η-Cu6Sn5 phase and even for the ε-Cu3Sn, pointing to the need of further investigation to clarify the present findings.