DOI QR코드

DOI QR Code

Evaluation of Fracture Toughness of Copper Thin Films by Combining Numerical Analyses and Experimental Tests

해석과 실험을 결합한 구리 박막의 파괴인성 평가

  • Kim, Hyun-Gyu (Dept. of Mechanical and Automotive Engineering, Seoul National University of Science & Technology) ;
  • Oh, Se-Young (Dept. of Mechanical and Automotive Engineering, Seoul National University of Science & Technology) ;
  • Kim, Kwang-Soo (Dept. of Mechanical and Automotive Engineering, Seoul National University of Science & Technology) ;
  • Lee, Haeng-Soo (Mechanical Engineering, Ulsan College) ;
  • Kim, Seong-Woong (Korea Institute of Materials Science (KIMS)) ;
  • Kim, Jae-Hyun (Korea Institute of Machinery & Materials (KIMM))
  • 김현규 (서울과학기술대학교 기계자동차공학과) ;
  • 오세영 (서울과학기술대학교 기계자동차공학과) ;
  • 김광수 (서울과학기술대학교 기계자동차공학과) ;
  • 이행수 (울산과학대학교 디지털기계학부) ;
  • 김성웅 (재료연구소) ;
  • 김재현 (한국기계연구원)
  • Received : 2012.07.26
  • Accepted : 2012.09.19
  • Published : 2013.02.04

Abstract

In this paper, a method of combining numerical analyses and experimental tests is used to evaluate fracture toughness of copper thin films of $15{\mu}m$ thickness. Far-field loadings of a global-local finite element model are inversely estimated by matching crack opening profiles in experiments with numerical results. The fracture toughness is then evaluated using the J-integral for cracks in thin films under far-field loadings. In experiments, Cu thin films attached to Aluminum sheets are loaded indirectly, and crack opening profiles are observed by microscope camera. Stress versus strain curves of Cu thin films are obtained through micro-tensile tests, and the grain size of Cu thin films is observed by TEM analysis. The results show that the fracture toughness of Cu thin films with $500nm{\sim}1{\mu}m$ sized grains is $6,962J/m^2$.

Keywords

Thin Films;Fracture Toughness;Inverse Problems;Crack Opening Profile;Finite Element Analysis

Acknowledgement

Supported by : 서울과학기술대학교

References

  1. Jaeger, G., Endler, I., Heilmaier, M.,Bartsch, K. and Leonhardt, A., 2000, "A New Method of Determining Strength and Fracture Toughness of Thin Hard Coating," Thin Solid Films, Vol. 332, pp. 195-201.
  2. Cottrell, B. and Chen, Z., 2000, "Buckling and Cracking of Thin Films on Compliant Substrate Under Compression," Int. J. Fracture, Vol. 104, pp. 169-179. https://doi.org/10.1023/A:1007628800620
  3. Oh, C.S., Lee, H.J., Ko, S.G., Kim, S.W. and Ahn, H.G., 2003, "Comparison of the Young's Modulus of Polysilicon Film by Tensile Testing and Nanoindentation," Sensor and Actuators A: Physics, Vol. 117, No. 1, pp. 151-158.
  4. Holmgerg, K., Laukkanen, A., Ronkainen, H., Willin, K. and Varjus, S., 2003, "A Model for Stresses, Crack Generation and Fracture Toughness Calculation in Scratched TiN-Coated Steel Surface," Wear, Vol. 254, pp. 278-291. https://doi.org/10.1016/S0043-1648(02)00297-1
  5. Bravo-Leon, A., Morikawa, Y., Kawahara, M. and Mayo, M.J., 2002, "Fracture Toughness of Nanocrystalline Tetragonal Zirconia with Low Yttria Content," Acta Mater., Vol. 50, No. 18, pp. 4555-4562. https://doi.org/10.1016/S1359-6454(02)00283-5
  6. Xia, Z., Curtin, W.A. and Sheldon, B.W., 2004, "A New Method to Evaluate the Fracture Toughness of Thin Films," Acta Mater., Vol. 52, pp. 3507-3517. https://doi.org/10.1016/j.actamat.2004.04.004
  7. Kim, H.-G., Yi, J.-W., Kim, S.-W., Kim, K.-S. and Kumar, S., 2012, Fracture Toughness Measurement of Free-Standing Nanocrystalline Copper-Chromium Composite Thin Films, Submitted for Publication.
  8. Pallares, G., Ponson, L., Grimaldi, A., George, M., Prevot, G. and Ciccotti, M., 2009, "Crack Opening Profile in DCDC Specimen," Int. J. Fracture, Vol. 156, pp. 11-20. https://doi.org/10.1007/s10704-009-9341-8
  9. Masumura, R.A., Hazzledine, P.M. and Pande, C.S., 1998, "Yield Stress of Fine Grained Materials," Acta Mater., Vol. 46, No. 13, pp. 4527-4534. https://doi.org/10.1016/S1359-6454(98)00150-5
  10. Gertsman, V.Y., Hoffmann, M., Gleiter, H. and Birringer R., 1994, "The Study of Grain Size Dependence of Yield Stress of Copper for Wide Grain Size Range," Acta Mater., Vol. 42, No. 10, pp. 3539-3544. https://doi.org/10.1016/0956-7151(94)90486-3
  11. Lefebvre, S., Devincre, B. and Hoc, T., 2007, "Yield Stress Strengthening in Ultrafine-Grained Metals: A Two-Dimensional Simulation of Dislocation Dynamics," J. Mech. Phys. Solids, Vol. 55, pp. 788-802. https://doi.org/10.1016/j.jmps.2006.10.002
  12. Ashby, M.F. and Jones, F.R.H., 1980, Engineering Materials 1: An Introduction to Their Properties and Applications, Pergamon Press.
  13. Kumar, K.S., Suresh, S., Chisholm, M.F., Horton, J.A. and Wang, P., 2003, "Deformation of Electrodeposited Nanocrystalline Nickle," Acta Mater., Vol. 51, No. 2, pp. 387-405. https://doi.org/10.1016/S1359-6454(02)00421-4
  14. Kang, Y.-L., Zhang, Z.-F., Wang, H.-W. and Qin, Q.- H., 2005, "Experimental Investigations of the Effect of Thickness on Fracture Toughness of Metallic Foils," Mater. Sci. Eng. A, Vol. 394, pp. 312-319. https://doi.org/10.1016/j.msea.2004.11.044
  15. Lee, H.Y. and Yu, J., 2000, "Effects of Oxidation Treatments on the Fracture Toughness of Leadframe/Epoxy Interfaces," Mater. Sci. Eng. A, Vol. 277, pp. 154-160. https://doi.org/10.1016/S0921-5093(99)00536-5