• Mcdonald, Stuart
• Matsumura, S.
• Gu, Q. F.
• Yamamoto, T.
• Nogita, Kazuhiro
• Barry, J.

Abstract

The intermetallic compound Cu Snis a significant microstructural feature of many electronic devices where it is present at the solder-substrate interfaces. The time- and temperature-dependent thermomechanical properties of Cu Snare dependent on the nature and stability of its crystal structure, which has been shown to exist in at least four variants (η, η', ηand η ). This research details an additional newly identified monoclinic-based structure in directly alloyed stoichiometric Cu Snusing variable-temperature synchrotron X-ray diffraction (XRD) and transmission electron microscopy. The phase is associated with a departure from the equilibrium temperature of the polymorphic monoclinic-hexagonal transformation temperature. The new monoclinic phase can be treated as a modulation of four η -Cu Snunit cells plus one η'-Cu Snunit cell. It has been labeled as ηand has cell parameters of a = 92.241 Å, b = 7.311 Å, c = 9.880 Å and β = 118.95° determined from electron diffraction patterns. The XRD results could be fitted well to a Rietveld refinement using the new crystal parameters.

Topics

• impedance spectroscopy
• compound
• phase
• x-ray diffraction
• electron diffraction
• transmission electron microscopy
• intermetallic