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1 – 10 of over 9000G.K. Glass, S.N. Field and W.K. Green
Conductive coatings form the basis of a common anode system used in the cathodic protection of steel in concrete. One of the properties required by such a coating is a low sheet…
Abstract
Conductive coatings form the basis of a common anode system used in the cathodic protection of steel in concrete. One of the properties required by such a coating is a low sheet resistance (square resistance). This, together with the protection current density and anode connection geometry, determines the uniformity of the current distribution over the concrete surface. It is shown that the sheet resistance may be determined using a non‐destructive test employing a collinear four‐probe array. When a current (I), passed between the outer probes of an equally spaced four‐probe array, induces a voltage difference (δV) between the inner probes, the sheet resistance is given by (pgr;/ln2)x(dgr;V/I). The validity of the measured values may be assessed by the absence of any sensitivity to probe orientation and spacing. This technique may be used in the assessment of the quality of installed conductive coating anodes. The sheet resistance will depend on factors such as the thickness and age of the installed coating.
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Barbara Swatowska, Piotr Panek, Dagmara Michoń and Aleksandra Drygała
The purpose of this study was the comparison and analysis of the electrical parameters of two kinds of silicon solar cells (mono- and multicrystalline) of different emitter…
Abstract
Purpose
The purpose of this study was the comparison and analysis of the electrical parameters of two kinds of silicon solar cells (mono- and multicrystalline) of different emitter resistance.
Design/methodology/approach
By controlling of diffusion parameters, silicon mono- (Cz-Si) and multicrystalline (mc-Si) solar cells with different emitter resistance values were produced – 22 and 48 Ω/□. On the basis of current-voltage measurements of cells and contact resistance mapping, the properties of final solar cells based on two different materials were compared. Additionally, the influence of temperature on PV cells efficiency and open circuit voltage (Uoc) were investigated. The PC1D simulation was useful to determine spectral dependence of external quantum efficiency of solar cells with different emitter resistance. The silicon solar cells of 25 cm2 area and 240 µm thickness were investigated.
Findings
Considering the all stages of cell technology, the best structure is silicon solar cell with sheet resistance (Rsheet) of 45-48 Ω/□. Producing of an emitter with this resistance allowed to obtain cells with a fill factor between 0.725 and 0.758, Uoc between 585 and 612 mV, short circuit current (Isc) between 724 and 820 mA.
Originality/value
Measurements and analysis confirmed that mono- and multicrystalline silicon solar cells with 48 Ω/□ emitter resistance have better parameters than cells with Rsheet of 22 Ω/□. The contact resistance is the highest for mc-Si with Rsheet of 48 Ω/□ and reaches the value 3.8 Ωcm.
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This report discusses the physical, electrical, mechanical and thermal characteristics of polyimide conductive, resistive, and dielectric thick film compositions made for…
Abstract
This report discusses the physical, electrical, mechanical and thermal characteristics of polyimide conductive, resistive, and dielectric thick film compositions made for high‐temperature curing and coating on non‐flexible substrates (alumina). The effects of curing times and print direction on sheet resistivity are presented for conductive patterns. The rates of silver migration of silver loaded resins are examined under 100% relative humidity at 25°C and various gap distances. The effect of current limiting resistors on silver migration is also examined. The electrical characteristics of polyimide thick film (PTF) resistors such as temperature coefficient of resistance and drifts are examined. The relationship of aspect ratio versus mean resistance and sheet resistance, as well as distribution diagrams are presented. The printability and definition of conductor patterns relative to their thickness, separation and the direction of the prints are examined, while the electrical characteristics of crossovers such as voltage breakdown are also investigated.
Paweł Winiarski, Adam Kłossowicz, Jacek Wróblewski, Andrzej Dziedzic and Wojciech Stęplewski
The purpose of this paper is to characterize electrical properties of nickel-phosphorus (Ni-P) thin-film resistors made on FR-4 laminate in a wide range of temperature (from −180…
Abstract
Purpose
The purpose of this paper is to characterize electrical properties of nickel-phosphorus (Ni-P) thin-film resistors made on FR-4 laminate in a wide range of temperature (from −180 to 20°C).
Design/methodology/approach
The study was performed using resistors made of Ni-P foil with two different thicknesses (0.1 or 0.05 μm) and sheet resistances (100 or 250 Ω/sq), respectively. The resistance rectangular resistors had length and width from the range between 0.59 and 5.91 mm. The resistance versus temperature characteristics and their distribution as well as resistors ' durability to low-temperature thermal shocks were investigated.
Findings
The results showed almost linear temperature dependence of resistance with a negative temperature coefficient of resistance of about −95 ppm/°C for 250 Ω/sq layer and −55 ppm/°C for 100 Ω/sq layer. A very small dimensional effect was observed for sheet resistance as well as for R(T) characteristic. Thin-film resistors are also characterized by very high durability to low-temperature thermal shocks.
Originality/value
The results presented in this paper can be very useful for low-temperature applications of thin-film resistors made on printed circuit boards. They suggest possibility of wide applications of these components in a wide temperature range.
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Dominik Jurków and Grzegorz Lis
The purpose of this paper is to present the application of low temperature cofired ceramics (LTCC) technology in the fabrication of a novel electronic device, which consists of an…
Abstract
Purpose
The purpose of this paper is to present the application of low temperature cofired ceramics (LTCC) technology in the fabrication of a novel electronic device, which consists of an antenna amplifier integrated with temperature stabilizer. The temperature controller consists of a thick‐film thermistor and heater, which has been optimized using geometry to achieve uniform temperature distribution on the whole electronic substrate.
Design/methodology/approach
LTCC technology was applied in the fabrication process of the novel device. The temperature distribution on the ceramic substrate and temperature stabilization time were analyzed using an IR camera. The heating ability of the heater was tested in a climatic chamber. The heater and thermistors parameters variability were estimated using a basic mathematical statistic.
Findings
The integrated device ensures proper temperature conditions of electronic components if the ambient temperature is lower than −40°C.
Research limitations/implications
The presented device is just a first prototype. Therefore, the fabrication of the next structures and further experiments will be needed to improve structural drawbacks and to analyze precisely the device reliability and parameters repeatability.
Practical implications
The device presented in the paper can be applied in systems working at very low ambient temperatures (even at −5°C). Moreover, a temperature stabilizer can increase the temperature of the whole device above −40°C, therefore, standard electronic components (which can work down to −40°C) can be used instead of specialized ones (which can work below −40°C).
Originality/value
This paper presents a novel temperature stabilizer.
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R. Kuž, E. Kopřivová and J. Broukal
New resistor compositions prepared by using special kinds of glass, CdO and ruthenium compound have been developed. The properties of resistors prepared from various compositions…
Abstract
New resistor compositions prepared by using special kinds of glass, CdO and ruthenium compound have been developed. The properties of resistors prepared from various compositions were tested in relation to peak firing temperature varying in the range from 760°C up to 850°C. In this way conditions were found for resistor preparation with constant, positive and relatively high TCR (2,500 ppm/°C) and high long‐term stability at 95% relative humidity at 40°C, and with various sheet resistivity (500 ohms/sq.?3,000 ohms/sq.). This system is typical in containing only small amounts of ruthenium compound ranging from 6 wt % to 12 wt %. The resistors can be used for temperature measurement as temperature sensors.
Chun‐lin Zhang, Yong Zhang, Fang‐cong Wang, Ying Wei, Xiao‐yun Jia and Su Liu
The purpose of this paper is to study the effect of on device performance by selectively annealing ITO substrates and TPD:PVK layers of the OLED at different temperatures with a…
Abstract
Purpose
The purpose of this paper is to study the effect of on device performance by selectively annealing ITO substrates and TPD:PVK layers of the OLED at different temperatures with a certain annealing time.
Design/methodology/approach
Thermal annealing was carried out on the ITO anode at different temperatures (150, 350, 500°C) with a constant time (100 min); but also before the deposition of the tris(8‐hydroxyquinolato) aluminum (Alq3) layer, at the same time, thermal treatment was carried out on the hole transporting layers (TPD:PVK layers) at different temperatures (70, 90, 110°C), and the annealing time was 30 min. We fabricated a novel device with the structure of Al/LiF/Alq3/TPD:PVK/NiO/ITO/Glass, and tested the sheet resistance, SEM and XRD of ITO anode after annealing, at the same we also tested the I‐V, L‐V and current efficiency characteristics of OLED.
Findings
When the TPD:PVK layers were annealed at 90°C with 30 min annealing time and ITO substrates were annealed at 350°C with a constant annealing time (100 min), we find that the OLED shows obvious performance improvement, which is attributable to the fact that annealing reduces defects and improves the interface structures of organics and organic/ITO interface. On the other hand, an annealing TPD:PVK layers would slow and even impede the transport of holes, and finally leads to more balanced electron and hole injection processes.
Originality/value
The paper shows that the annealing method can be used to prepare high‐performance organic light‐emitting device.
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E.H. Jewell, S.M. Hamblyn, T.C. Claypole and D.T. Gethin
The purpose of this paper is to carry out a comprehensive experimental investigation into the role of screen and conductive carbon material formulation on line conductivity and…
Abstract
Purpose
The purpose of this paper is to carry out a comprehensive experimental investigation into the role of screen and conductive carbon material formulation on line conductivity and printing capability in the screen printing process, to provide design knowledge and further understanding of the screen printing for printed carbon.
Design/methodology/approach
A full factorial experiment was carried out where six carbon materials were printed through ten screens to a polyester substrate under a set of standard conditions.
Findings
Material characterization showed that viscosity and the corresponding viscous and elastic material modulli increased with solids content and that the elastic properties at low shear are significant. The solids carbon content materials were unable to produce the minimum printable line features possible with the low carbon materials. Increasing the solids contents reduced the final cured line resistance, reduced the printed line width, increased the film thickness, increased the cross sectional area and reduced the material resistivity. Material resistivities were around 700 to 950 μΩcm were obtained in the printed lines.
Research limitations/implications
Lower material resistivities were obtained with higher solids materials and it is postulated that the increased visco‐elastic nature of the solids content materials, play a role in determining the microscopic structure of the cured film through alignment of the carbon graphite platelets.
Practical implications
A dataset which allows material, screen and print characteristics has been created allowing process optimization and formulation development to be accelerated.
Originality/value
The work provides insight into the role of material properties and process settings on the electrical and physical characteristics of printed carbon.
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Philip Ivanov Philippov, Milka Markova Rassovska, Radosvet Georgiev Arnaudov, Vassil Angelov Ianev and Minka Draganova Gospodinova
Recent progress in the investigation of the material parameters of Al/Al2O3systems leads to an increase in the possibilities for using embedded TaOXN1‐X layers. The use of Al…
Abstract
Recent progress in the investigation of the material parameters of Al/Al2O3systems leads to an increase in the possibilities for using embedded TaOXN1‐X layers. The use of Al‐sheets as mechanical strength carriers in combination with vacuum‐deposited Al‐layers and electrochemically anodized Al2O3 structure requires study. This was found to create a periodic multilayer Al/Al2O3 structure. The material qualities of this system allow optimization in order to achieve high speed data processing and signal propagation. The existing studies using Al and Ta combination as well as the high resistance qualities of the modified TaOXN1‐X layers have shown satisfactory results. It can be concluded that the development of this new layer combination is possible in the multilayer carrier structures. Some preliminary research studies show a proper adhesion and satisfactory characteristics of the two integrated resistive planes in the multilayer combination Al/Al2O3//TaOXN1‐X/Ta2O5/Al.
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With the increasing severity of the ever‐expanding range of synthetic detergents being made available, the question of the resistance of enamels to attack by them becomes more…
Abstract
With the increasing severity of the ever‐expanding range of synthetic detergents being made available, the question of the resistance of enamels to attack by them becomes more important. Testing apparatus and methods used for the evaluation of the resistance of these finishes are covered in this article as well as the factors affecting their resistance.