Phase formation at the Sn/Cu interface during room temperature aging: Microstructural evolution, whiskering, and interface thermodynamics

• Published in: Journal of materials research Vol. 26; no. 12; pp. 1482 - 1493
• Main Authors: Sobiech, Matthias, Krüger, Carmen, Welzel, Udo, Wang, Jiang-Yang, Mittemeijer, Eric Jan, Hügel, Werner
• Format: Journal Article
• Language: English
• Published: New York, USA Cambridge University Press 28-06-2011; Springer International Publishing; Springer Nature B.V
• Subjects: Aging; Alloys; Applied and Technical Physics; Biomaterials; Coating; Copper; Energy; Evolution; Grain boundaries; Inorganic Chemistry; Interdiffusion; Interfaces; Intermetallic compounds; Intermetallic phases; Ion beams; Materials Engineering; Materials research; Materials Science; Metals; Microscopy; Morphology; Nanotechnology; Polycrystals; Room temperature; Solid solutions; Spontaneous; Substrates; Thermodynamics; Thickness; Thin films; Tin; Transmission electron microscopy; X-ray diffraction; Crystal growth; Filamentary; Microstructure
• ISSN: 0884-2914; 2044-5326
• DOI: 10.1557/jmr.2011.162

The time-resolved evolution of intermetallic phase formation in the system pure Sn (polycrystalline coating with a thickness of several microns) on pure Cu (polycrystalline bulk substrate) was investigated in detail by means of focused ion beam and transmission electron microscopy and x-ray diffraction during aging at room temperature for a period of about 1 year. The availability of this coherent data base allowed interpretation of the evolution of intermetallic compound (IMC) formation in terms of interface thermodynamics and interdiffusion kinetics. On this basis spontaneous Sn whiskering on the surface of the Sn coating as a consequence of intermetallic phase (Cu6Sn5) formation along, specifically, Sn grain boundaries intersecting the Sn/Cu interfaces could be discussed. Moreover, a treatment to mitigate spontaneous Sn whiskering on the basis of thermodynamic control of the IMC morphology was proposed.