Effects of Al and Fe additions on microstructure and mechanical properties of SnAgCu eutectic lead-free solders


KANTARCIOGLU A., KALAY Y. E.

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, vol.593, pp.79-84, 2014 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 593
  • Publication Date: 2014
  • Doi Number: 10.1016/j.msea.2013.11.025
  • Title of Journal : MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
  • Page Numbers: pp.79-84

Abstract

In this study, Sn-3.5Ag-0.9Cu (wt%) lead-free solder was modified with minor additions of Al and Fe. The thermal, microstructural and mechanical behaviors after and before compositional modifications were investigated by a combined study of differential scanning calorimetry (DSC), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and shear strength measurements. EDS results and Darken-Gurry predictions indicated a high concentration of Fe substitution within the Cu6Sn5 at the solder/copper interface which induced desirable effects on undercooling and microstructure evolution. Eutectic SAC and SAC+0.05 wt% Al solder joints exhibit considerable number of brittle proeutectic phases (i.e., Ag3Sn). Proeutectic Ag3Sn formation was found to be suppressed after Fe modification. A new type of Al-Sn-Cu intermetallic compound was detected for Al added specimens. The rod-like morphology of this IMC appears to cause a sharp decrease in the shear strength of Al modified solder joints. The shear strength values for Fe modified solder joints were found to be higher in a wider composition range (0.01-0.1 wt% Fe) as compared to eutectic SAC and SAC+0.05 wt% Al. (C) 2013 Elsevier B.V. All rights reserved.