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Multiphase Characterization of sellected isopleths of Cu-In-Sn system for Pb-free TLPB

Thursday (27.09.2018)
10:00 - 10:15 S1/01 - A02
Part of:

Cu-In-Sn alloys are among the suggested materials to replace Pb-Sn alloys traditionally used in joining processes by the electronic industry. Thorough thermodynamic understanding is required for the selection/design of adequate and efficient alloys for specific applications. Understanding the effects that high cost elements such as In have on microstructure and phase stability is imperative for industrial use. In this work ternary alloys were prepared by melting high purity elements (5N) for selected compositions of Cu isopleths, and cooling down to reproduce process conditions. Chemical composition was determined using scanning electron microscopy equipped with electron probe microanalysis. Measurements of transition temperatures were done by heat-flux differential scanning calorimetry. We present a comprehensive comparison between our experimental results and phase diagram calculations using Liu et al. (J Electron Mater 30:1093, 2001) thermodynamic description based in the CALPHAD method, available in the literature. Additionally, a structural investigation of the Cu-In-Sn intermetallic phases was carried out by comparing experimental results with simulated equilibrium diagrams. X-ray powder diffraction (XRPD) for phases structure and SEM/EDS for microstructural analysis were used. For each composition two types of samples were used: as melted with air cooling, and homogenized at 500 ºC during 40 days with quenching. Powders were prepared in an agate mortar and residual tensions were eliminated with adequate thermal treatments. Results indicate partial agreement between experimental data and simulated equilibrium diagram; obtained diffractograms were compared with binary phase’s patterns, since ternary ones are not available in literature. Observed differences may be related with phase transformations occurring far from equilibrium state in as melted samples, as a result of heating/cooling rates in the synthesis. On the other hand, structural changes correlated with temperature show evidence for invariant temperatures and phase fields considerations. To deal with observed inconsistencies, additional diffraction experiments are planned by combining other experimental techniques, as well as, a possible revision of the simulated phase diagrams

Prof. Dr. Silvana Sommadossi
National University of Comahue
Additional Authors:
  • Dr. Paula Alonso
  • Dr. Diego Lamas
    National University of San Martin UNSAM
  • Dr. Suzana Fries
  • Silvana Tumminello


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