Influence of Interfacial Delamination on Channel Cracking of Brittle Thin Films

H. Mei, Y. Pang, and R. Huang, International Journal of Fracture 148, 331-342 (2007).

Following a previous effort published in MRS Proceedings, we wrote a journal article of the same title, with more numerical results. While the main conclusions stay the same, a few subtle points are noted in this paper.

First, instead of using the approximate formula by Ye, Suo and Evans (1992), we calculate the energy release rate of interfacial delamination emanating from the channel crack exclusively by the finite element method. We found that the approximate formula is not accurate in several cases.

Second, the numerical results for interfacial delamination are compared with asymptotic solutions for short cracks (He and Hutchinson, 1989), and the agreement is very good. It is noted that the asymptotic behavior is quite different from those under other edge effects (Yu, He and Hutchingson, 2001).

Third, a delamination map is constructed with respect to the elastic mismatch and normalized interface toughness, where the boundary between channel cracking with and without interfacial delamination is determined numerically (slightly different from the previous MRS paper).

Finally, the implications of the present results on reliability of integrated structures in microelectronics and flexible electronics are discussed toward the end of the paper.