Growth nature of in-situ Cu6Sn5-phase and their influence on creep and damping characteristics of Sn-Cu material under high-temperature and humidity

• Autores: Asit Kumar Gain, Liangchi Zhang
• Localización: Microelectronics reliability, ISSN 0026-2714, Nº. 87, 2018, págs. 278-285
• Idioma: inglés
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• Resumen

  • This paper describes the morphology and growth nature of in-situ Cu6Sn5 intermetallic compound (IMC) and their impacts on material properties of an environmental-friendly Sn-0. 7Cu (wt%) material when exposed to high-temperature (85 °C) and relative humidity (85%) environments. A detail microstructural characterization is carried-out by electron microscopy e.g., SEM, EBSD and TEM techniques. In as-cast Sn-Cu material, along with the fine matrix Sn grains, the in-situ Cu6Sn5 IMC in grain boundary and interior grain appear with a dimension of submicron size and more consistently spread in the matrix. Such fine and uniform dispersed IMC acted as a pinning effect that obstacle the dislocation movement and enhanced their hardness and creep performance. In contrast, after exposing at harsh environment, such in-situ IMC phase morphologies are changed and seemed to a coarse elongated-shaped IMC and reduced their aspect-ratio. These morphological changes negatively impact on the mechanical reliability of Sn-Cu material. A contrast between the as-cast specimen and specimen exposed to high-temperature and relative humidity presents that the electrical resistivity reduces to 12%, where their hardness degrades about 18.5%. However, it is worthy noted that the coarse IMC positively impacts on damping property of Sn-Cu material at given a strain and temperature.