An Investigation of Fatigue Characteristics of Copper Film

• Published in: Experimental mechanics Vol. 51; no. 7; pp. 1033 - 1038
• Main Authors: Huh, Y. H., Kim, D. I., Kim, D. J., Lee, H. M., Hong, S. G., Park, J. H.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.09.2011; Springer
• Subjects: Biomedical Engineering and Bioengineering; Characterization and Evaluation of Materials; Control; Dynamical Systems; Electron, positron and ion microscopes, electron diffractometers and related techniques; Engineering; Exact sciences and technology; Fracture mechanics (crack, fatigue, damage...); Fundamental areas of phenomenology (including applications); Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Lasers; Measurement and testing methods; Optical Devices; Optics; Photonics; Physics; Solid Mechanics; Structural and continuum mechanics; Vibration; ESPI technique; S-N curve; Fatigue limit; Load ratio; Copper film; Tensile properties; Cyclic loads; Ultimate limit; Chemical etching; Coatings; Fatigue fracture; Speckles; Load control; Copper; Electronic speckle pattern interferometry; Stress measurement; Light interferometry; Scanning electron microscopy; Fatigue testing; Tensile tests; Fatigue; Layer thickness; Optical measurement; Fracture surfaces; Ductile fracture; Microstructure; Fractography
• ISSN: 0014-4851; 1741-2765
• DOI: 10.1007/s11340-010-9412-9

Tensile and fatigue behaviors of the copper film coated by tin (Sn) were investigated considering S-N relationships and scanning electron microscope (SEM) observation of fracture surfaces. The fatigue behavior was investigated considering the effect of load ratio, R. The specimen of 2000 μm width, 8000 μm length and 15.26 μm thickness was fabricated by etching process. Tensile properties were measured using the micro-tensile testing system and in-plane electronic speckle pattern interferometric (ESPI) system for measuring the tensile strain during the test. The fatigue tests of the film were carried out in load-control mode with 40 Hz at three different stress ratios of 0.05, 0.3 and 0.5. The S-N curves, including the slope of the curve and fatigue limit, at the respective stress ratios were obtained. These curves were dependent on the load ratio. Empirical relationships indicating the dependency of the fatigue limit and S-N curve on the load ratio were suggested in this study. SEM observation of the tensile fracture surface showed that the cross-sectional area of the testing section was necked in the direction of the film thickness (i.e. parallel to the substrate surface normal) and some ductile dimples in the fracture surface were present. The fracture of the copper film under cyclic loading was progressed in the transgranular fracture mode.