19 January 2007 Mechanics of thin film adhesion-delamination subjected to residual stress and interfacial adhesion: application to MEMS-RF-switch
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This paper is an extended work of our previous models [1-5] and an introduction of an experiment along this line. For the 1-D model, a pre-stressed rectangular stiff film clamped at both ends delaminates from a rigid punch. According to thermodynamic energy balance, the delamination mechanics in term of external tensile force applied to the punch, punch displacement, and contact area. Coupling effect of tensile residual stress, film-punch interfacial adhesion energy is discussed in this paper. "Pinch-off" (stable shrinking of the contact area to a line) is predicted at the moment when film is completely detached from substrate. The 1-D model can be further extended to a 2-D axisymmetric model. A thin circular film clamped at the periphery is adhered to the planar surface of a rigid cylindrical punch. An external tensile load is applied to the punch causing the film to delaminate from the substrate and the circular contact edge to contract. The film spontaneously separates from the punch, or, "pull-off", when the contact radius reduces to a range between 0.1758 and 0.3651 of the film radius, depending on the magnitude of the residual membrane stress. The constitutive relation of the delamination process is derived by a thermodynamic energy balance based on a coupled interfacial adhesion and residual membrane stress. The models are useful in understanding the behavior of various adhesion-delamination phenomena, such as capacitive MEMS-RF switches, micro pumps, micro-structure network, and nano-structures. Experiment is carried out simulating the axisymmetric model and will be presented in this conference.
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Ming Fung Wong, Ming Fung Wong, Kai-Tak Wan, Kai-Tak Wan, } "Mechanics of thin film adhesion-delamination subjected to residual stress and interfacial adhesion: application to MEMS-RF-switch", Proc. SPIE 6463, Reliability, Packaging, Testing, and Characterization of MEMS/MOEMS VI, 646307 (19 January 2007); doi: 10.1117/12.709074; https://doi.org/10.1117/12.709074

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