Research On The Stretchablity Of The Metal Film On Elastomeric Substrate

Flexible electronics technology is attracting an increasing number of researchers, and people gradually pay attention to the flexible products, such as folding displays. The metal film conductor is the place where breakage will easily happen in the basic structure of flexible electronics. As a result, this thesis focus on the stretchability,fracture and its associated factors of the thin metal film on elastomeric substrate by the finite element method.First, Different ductility of metal film is approximated by adopt corresponding CZM parameters to study the effects of the ductility of metal films on the stretchability of metal film-substrate structure. The results show that the stretchability of the film-substrate structure and freestanding thin film is almost the same, however, that of the former one greatly enhanced as the ductility of the film becomes greater for suppressing necking of the film.Second, the influence on the stretchability of the copper film on elastomeric substrate is investigated by considering packaging materials properties, geometric parameters of packaging materials and the geometric imperfections of the copper thin film. The results show that the packaging material of elastic modulus has a certain effect on the ductility. Especially when the metal film has defects, the packaging materials have a greater impact to the ductility of the structure. The depth of the defect in the metal film has more significant impact on the stretchability than the width of the defect.Finally, the temperature and the thermal stress in the device during work is calculated. On the basis of above, the stress in the metal film that result from the change of mechanical properties of the PDMS material due to environmental temperature is analyzed. Results and research method in this paper provide some theoretical and practical significance for the design of flexible electronic devices.