Interface reaction systematics in the Cu/Ine48Sn/Cu system

S. SOMMADOSSI , A. FERNÁNDEZ GUILLERMET

INTERMETALLICS

Año: 2007 vol. 15 p. 912 - 917

0966-9795

An alternative lead-free solder alloy In-48at%Sn with a melting point of 120 °C and its implementation to bond Cu substrates in a diffusion soldering joining method are presented. According to the EPMA, TEM/EDX and electron diffraction analyses, two different behaviors were observed in the interconnection zone depending on the temperature range: (i) a single layer consisting of h phase below 200 °C; (ii) a Cu-poor region consisting of h phase and a Cu-rich layer formed by a mixture of thin alternate regions of psi-Cu10Sn3 and delta-Cu7In3 phases perpendicular to the interconnection plane above 200 °C. The h layer shows two morphologies: large grains and fine grains at the eta/In-48Sn (liquid) and at the eta/Cu-rich interfaces, respectively. Additionally, the ç region shows a gradual change in composition, suggesting a change from the Cu6Sn5 to the Cu2In structures. Thermal stability tests indicate that the thermal resistance of the bonds is about 750 °C.