Effect of isothermal aging on intermetallic compound layer growth at the interface between Sn-3.5Ag-0.75Cu solder and Cu substrate

摘要

Intermetallic compound (IMC) growth during solid-state isothermal aging at temperatures between 100 and 200°C up to 60 days for Sn-3.5Ag-0.75Cu solder on Cu substrate was investigated. A quantitative analysis of the IMC layer thickness as a function of aging time and temperature was performed. Diffusion couples showed a composite IMC layer comprised of Cu6Sn5 and Cu3Sn. After isothermal aging at temperature over 120°C, the solder/Cu interface exhibited a duplex structure of Cu6Sn5 and Cu3Sn intermetallics. The growth of IMCs followed diffusion-controlled kinetics and the layer thickness reached 13 μm after 60 day of aging at 170°C. The apparent activation energies calculated for the growth of the total IMC (Cu6Sn5 + Cu3Sn), Cu6Sn5 and Cu3Sn intermetallic are 62.6, 49.1 and 80.1 kJ/mol, respectively.