Recently, there has been a tremendous rise in production of portable electronic devices. To produce flexible devices, flexible substrates should replace conventional glass substrates. Indium-tin-oxide (ITO) is the preferred transparent conducting layer used in the display technology. Although ITO has excellent sheet resistance and very good optical properties, ITO can crack at very low tensile strains which might cause failure in the conductive layer because of the unusual structure of a very thin film of brittle ceramic material applied to a polymer substrate. Therefore, the mechanics of ITO on flexible substrates has been thoroughly considered in the design and manufacturing of flexible devices. In a typical roll-to-roll manufacturing process, many challenges exist during the travel of the coated web over the rollers which produce bending stresses that might cause failure even if the stresses are below the yield strength of the material. Therefore, the high cycle bending fatigue of ITO thin films on flexible substrates is of a significant importance. In this work, high cycle bending fatigue experiments were conducted on ITO coated PET substrate. The effect of bending diameter, bending frequency, and sample width on the change in electrical resistance was investigated. High magnification images were obtained to observe crack initiation and propagating in the ITO layer. The goal of this work is to establish a baseline for a comprehensive reliability study of ITO thin films on flexible substrate. It was found that bending diameters as well as the number of bending cycles have a great influence on the electrical conductivity of the ITO layer.

Indium-tin-oxide (ITO) is a transparent conductive thin film that is widely used as a top conducive layer in photovoltaic solar cells. However, ITO is sensitive to environmental conditions and the electrical conductivity degrades as a consequence of harsh environmental conditions. Furthermore, the thermal expansion coefficient mismatch between the ITO film and the substrate creates stress/strain on the film when the package is subjected to fluctuating temperatures. This could create micro-cracks and consequently damage the film. Therefore, this study was designed to study the effect of the thermal cycling and thermal aging on the ITO thin films to simulate the effect of continuous high temperatures and fluctuating temperatures that may be applied on the thin films during the usage. In this study, two sets of experiments were conducted on a 60Ω/□square sputter-deposited ITO on 127 μm heat stabilized Poly Ethylene Terephthalate (PET) substrate. The first set of experiments contained four samples which were thermally aged at 100^°C for 30 days and the other set of experiments contained another four samples which were thermally cycled for 900 cycles. The thermal profile consisted of a high temperature of 100^°C, a low temperature of 0^°C, dwell time of 10 minutes, and ramp rate of 10^°C/min , as depicted in Fig. 1. The initial results showed that the ITO thin film is not stable in the thermal aging experiment and the electrical resistivity gradually increased for all samples until the end of the 30 days. The degradation happened during the thermal cycling as well. However, SEM images show that the morphology of the ITO surface is stable under both conditions. Energy-dispersive X-ray (EDX) spectroscopy analysis showed stability in the ITO thin film in terms of composition. XRD spectra confirmed the improved crystallinity for the thermally aged films, which corresponded to the increased transmission in the visible region.

This paper addresses the behavior of thin-film metal coated flexible substrates under high cyclic bending fatigue loading. Polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) are widely used substrates in the fabrication of microelectronic devices. Factors affecting the fatigue life of thin-film coated on a flexible PET substrates were studied, including thin-film thickness, film material, bending radius, temperature, and humidity. A series of experiments for sputter-deposited copper and aluminum coated on a PET substrate were conducted. Electrical resistance and crack growth rate were monitored during the experiments at specified time intervals. In addition, a finite element model was built to simulate the bending of thin-films on flexible substrate structure. Layered shell elements were used in the model. Stress intensity and stress distribution across the film were obtained and compared with the experiments. Initial results of copper-coated PET showed a great agreement between the model and the experimental results.

Car parking is a serious problem in Gulf Cooperation Council (GCC) countries in general and in United Arab Emirates (UAE) in particular. This problem has been associated with the exceptional growth in the number of cars, buses, trucks, and other modes of transportation over the past few decades. In Abu Dhabi (the capital city of UAE), finding a parking at some locations is a real challenge due to the lack of available parking slots in the city. In 2009, in order to organize the randomness in parking management in Abu Dhabi, Abu Dhabi City started implementing a new paid parking system inside the city, named MAWAQIF. This new system helps in reducing the parking problem in congested areas, yet has transferred the problem to less crowded areas in the city. Furthermore, the number of parking lots provided in the controlled areas isn’t enough to satisfy the demand in these areas. This article concentrates on this direction and focuses on two aspects. First, a survey was prepared and distributed to 500 participants as a part of a project, in order to identify the scale of the parking problem in Abu Dhabi. Then, a technical framework for developing an intelligent mobile application for improving the indoor parking management system in Abu Dhabi was developed. Results indicate that the proposed mobile application will help in reducing the time wasted in searching for parking and will increase the efficiency of the parking system in Abu Dhabi