Papers by Keyword: Screen Printing

Abstract: With the development of technologies in printed electronics, they are perfect for low performance applications, such as displays, labels, clothing, and batteries. Flexible, electrical circuits can be printed using functional inks and printing methods, such as screen printing, gravure and inkjet. Uniform ink surface, smoothness, fine lines, and registration are keys in determining the capability of printed electronics. Screen mesh count, printing methods and emulsion thickness are all variables that are involved in screen printing and need to be quantified in order to determine optimal operational conditions. Inkjet printing is used to conductive traces based on its tiny drop. This study attempted to control human errors during operation that might influence electrical conductivity with inkjet and screen printing.

Abstract: The Solid Oxide Fuel Cell Roll (SOFCRoll) is a novel design based on a double spiral. Combining structural advantages of tubular geometries with processing advantages of thick film methods, it utilises a single cofiring process. The initial concept used separate tape cast layers which were laminated before rolling. To optimise layer thickness to function, thinner screen printed layers were combined into the tape cast structure in 2^nd generation cells. This presented several processing challenges, such as achieving dense electrolyte layers, maintaining porous electrode and current collecting layers and incorporation of integral gas channels. Performance has been promising with open circuit voltages close to 1V and cell power of over 400mW at 800°C, however cracking is still evident. Therefore further iterations are in development where thinner layers are sequentially cast, aiming to improve interfacial bonding and better match plasticity and burn out to reduce cracking. This paper reviews key aspects of understanding and development of the SOFRoll , the challenges that have been tackled and what challenges remain, along with future directions for development and potential applications for this device.

Abstract: The increasing fresh water deficiency due to environmental pollution demands accurate, reliable and highly sensitive sensors for online monitoring of water pollution. Solid state sensors are helpful for fabricating and implementing low cost wireless sensors for monitoring of pollution. In water pollution determination, the measurement of pH plays an important role. Among the semiconductor sensitive materials RuO₂ shows good sensitivity to hydrogen ions, high accuracy and resistance to interferences caused by other dissolved ions. In this work, thick film RuO₂ based pH sensitive electrodes are fabricated by screen printing. The sensors were characterized by electromotive force measurements, SEM, optical microscopy and EDS analysis. The effects of sheet resistivity of the material and storage conditions are discussed. The sensor exhibits a sensitivity of 60 mV/pH in wide pH range of 2 to 10. The obtained response was very close to the theoretical Nernstian behavior. The best performance was attained for a sensor fabricated from 10 kΩ/sq. thick film paste and stored at water for 25 days.

Abstract: In this paper there wasdevelopeda CNT based sensor applied to the tested material and integrated with it. MWCNTs weremixed with polymer and then applied to the materials (fiber glass composites) with the use of screen printing. The surface and the inner part of the sensing material were investigated using SEM. The most importantand noticeable thing was dispersion of CNTs in epoxy.Moreover, the sensors were tested under the different loads. There were three runs for the same compositions of CNT/epoxy. Results from the test runs were compared to the images from SEM and discussed. Screen printing technique has shown promising results for the application and integration of the sensors on the base materials leading to the conclusion to do more research for the screen printing technique for application of CNT/epoxy sensors for large area appliaction and variant environments.

Abstract: Fresh water deficiency caused by climate change calls for employing novel measures to ensure safety of drinking water supply. Wireless sensor networks can be used for monitoring hydrological conditions across wide area, allowing flow forecasting and early detection of pollutants. While there are no fundamental technological obstacles to implementation of large area sensor networks, their feasibility is constrained by unit cost of sensing nodes. This paper describes a low-cost pH sensor, intended for use in fresh water monitoring. The sensor was fabricated in a standard thick film process, and an off-the-shelf resistive paste was used as a sensing material. For the fabrication of sensor, RuO₂ resistive paste was screen printed on the alumina substrate with silver conducting layer. Test solutions with pH ranging from 2 to 10 were prepared from HCl or KOH solutions. The potential difference between reference and sensing electrode (electromotive force emf of an electrochemical cell) should be proportional to the pH of a solution according to the Nernst equation. The fabricated sensor exhibits Nernstian response to pH. Influence of storage conditions on sensing performance was also investigated.

Abstract: 0.67BiFeO₃-0.33BaTiO₃ thick films were prepared by screen printing pastes prepared by kneading the 0.67BiFeO₃-0.33BaTiO₃ powder in a three-roll mill with an organic vehicle. The thick films were fired with Pt bottom electrodes and ZrO₂ substrates to investigate the influence of firing temperature. The microstructures and ferroelectric properties of the thick films were examined and compared with the bulk ceramics. A remanent polarization of 32.0 μC/cm² and coercive field of 28 kV/cm were obtained for a thick film with the addition of 0.5 wt% MnO that was fired at 1050 °C.

Abstract: Colorless fluorescent ink has certain anti-counterfeiting function. In this paper, fluorescence curve and spectral properties of the fluorescent ink with colors of fluorescent red, fluorescent blue and fluorescent green used for screen printing are tested. Besides, rheological properties of fluorescent inks such as viscosity and thixotropic behavior are shown in the paper.

Abstract: For the traditional operation mode of high strength, low efficiency in the process of the plastic ruler screen printing, the powerful PLC is used as the control core, the automatic PLC control system is developed, and the reasonable programming skills are applied so that the two institutions can work in parallel, which greatly improves the production efficiency. At the same time, sophisticated sensors are used to detect each action execution state so as to ensure that work is reliable with stable performance. Through actual production test, the printing speed has reached the capacity of 28 rulers on average per minute, and has achieved the good production benefit.

Abstract: As an environmentally friendly technology, the fuel cell is one of the alternative technologies that can replace fossil fuels. Various types of fuel cells are available in the market, including the solid oxide fuel cell (SOFC). The planar and tubular designs of SOFC are the leading designs mentioned in the literature. Several factors such as manufacturing cost, manufacturing process and production scale differentiate between the two main designs. Each cell component can be produced using a number of methods, two of which are the most common, namely dry pressing and screen printing techniques for the making of planar SOFC. This paper thus reviews several works that have utilized each of the fabricating methods mentioned. The processing steps, technical parameters, and results, such as the maximum power density of each method are discussed.

Abstract: Color film printing is a special printing. Screen printing is an important part of Color film printing. Because the process of screen printing in color film printing is complex, its printing quality is affected by various factors. This paper proposes a set of normative test methods about standard operating, which is to find out these factors of Screen overprinting in Color film printing by actual test in production. And it is to improve product quality at the same time.