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Experimental and Analytical Studies of the High Cycle Bending Fatigue of Thin Films on Flexible Substrates for Flexible Electronics Applications

出版	State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Systems Science and Industrial Engineering, 2010
ISBN	11244113729781124411378
URL	http://books.google.com.hk/books?id=E4tTAQAACAAJ&hl=&source=gbs_api

註釋Fatigue is a common failure mechanism that is responsible for most of the structural and electrical failures in microelectronic systems. In roll-to-roll (R2R) processing steps of flexible substrates, bending and tensile loadings are repeatedly applied to the substrate. Such loadings are responsible for the dimensional instability in the substrate. The primary objective of this research is to study the behavior of thin film on flexible substrates under high cycle bending fatigue loading. Polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and Kapton are widely used substrates in the fabrication of microelectronic devices. Factors affecting the fatigue life of thin films on flexible PET substrates were studied, including film thickness, film material, bending radius, temperature, and humidity. A series of experiments for sputter-deposited copper and aluminum on PET substrates were conducted. Electrical resistance and crack growth rate were monitored during the experiments at specified time intervals. Another objective of this research is to use finite element modeling (FEM) to simulate the bending of thin films on flexible substrate structure. Layered shell elements were used in the model. Stress intensity and distribution across the film were obtained and compared with the experiments. Initial results of sputtered copper and aluminum on PET substrate showed a great agreement between the model and the experimental results. Finite element models were used to study the stress/strain distribution in the thin film as well as the plastic substrate. Design of Experiments (DOE) tools were used to study the effects of structural, loading, and environmental conditions on the maximum stresses developed in each layer of the structure.