Wrinkling of thin films on compliant substrates. Rui Huang Center for Mechanics of Solids, Structures and Materials The University of Texas at Austin. Au films on PDMS (Bowden et al., Nature 393, 146, 1998). SiO 2 on Si (Courtesy of David Cahill). Wrinkling of thin films.
Wrinkling of thin films on compliant substrates
Center for Mechanics of Solids, Structures and Materials
The University of Texas at Austin
Au films on PDMS
(Bowden et al., Nature 393, 146, 1998)
SiO2 on Si
(Courtesy of David Cahill)
Stretchable interconnects for large-area flexible electronics (Jones et al., MRS Symp. Proc. 769, H6.12, 2003 )
Wrinkling of skins (Cerda and Mahadevan, PRL 90, 074302, 2003)
Other equilibrium states: energetically unfavorable
Strain energy change per unit area:
Nonlinear effect: large deflection of the film
Energy minimization leads to the energetically favored wave number and the corresponding equilibrium amplitude:
The energetically favored mode is independent of the compressive strain.
Kinetics effect: growth rate depends on the driving force
Other nonlinear effects: plasticity, large deformation of substrate
Linear perturbation analysis:
Fastest growing mode
Growth rate, s
Slow growing long-wave mode
Wave number, kh
Huang and Suo, Int. J. Solids Struct. 39, 1791 (2002).
Infinitely many:each wavelength ( > c) has an equilibrium state
Energetically unstable: longer wavelength lower energy
Kinetically constrained: flow is very slow near the equilibrium state
Huang and Suo, J. Appl. Phys. 91, 1135 (2002).
Expansion starts at the edges and propagates toward center
Wrinkle grows before expansion relaxes the strain
Long annealing removes wrinkles by expansion
Liang et al., Acta Materialia 50, 2933 (2002).
Tensile stress at the equilibrium state:
A 200m by 200m SiGe island on BPSG annealed for 90 minutes at 790°C.
Huang et al., Acta Mechanica Sinica 18, 441, (2002)
Strain per cycle
Huang, Suo, Ma, Acta Materialia 49, 3039-3049 (2001).
Amplitude growth per cycle:
Huang et al., in preparation.
Zhigang Suo (Harvard University)
Zhenyu Huang (Harvard University)
Haizhou Yin (Princeton University)
James C. Sturm (Princeton University)
Jim Liang (Intel Corp.)
Se Hyuk Im (University of Texas-Austin)