Thick Film Resistors Research Articles

Fe2O3 Modified ZnO Thick Film Resistors as H2S Sensor

Fe2O3 Modified ZnO Thick Film Resistors as H2S Sensor

High–performance copper–substituted La0.5Sr0.5CoO3 ceramics as economical functional materials for thick film resistors

The demand for cost–effective materials for thick film resistors has driven the exploration of alternative functional materials to replace the traditionally used ruthenium oxides. This study investigates the synthesis and properties of copper–substituted La0.5Sr0.5CoO3 (La0.5Sr0.5Co1-xCuxO3, LSCCu, x = 0.02–0.10) ceramics as a potential economical substitute. The crystal structure, electrical performance, and sintering behavior of LSCCu with varying Cu2+ contents were characterized through solid–state reactions and first–principles simulations. The results indicate that the perovskite structure is maintained with increasing Cu2+, while the densification temperature, crystallinity, and conductivity decrease. Moreover, Cu2+ substitution reduced the DOS across the Fermi level and weakened the electron transport in LSCCu. The sample with x = 0.06 exhibited a promising conductivity of 2609 S/cm after sintering at 1150 °C, comparable to commercial thick film resistor materials. The temperature coefficient of resistance (TCR) of LSCCu showed a metallic behavior with a low value of 1148 ppm/°C for the x = 0.06 sample. Additionally, the LSCCu ceramics possess good long–term stability and frequency stability of resistance. These findings suggest that LSCCu ceramics are a promising economical material for thick film resistor applications.

Printed Thick Film Resistance Temperature Detector for Real-Time Tube Furnace Temperature Monitoring.

Accurately acquiring crucial data on tube furnaces and real-time temperature monitoring of different temperature zones is vital for material synthesis technology in production. However, it is difficult to achieve real-time monitoring of the temperature field of tube furnaces with existing technology. Here, we proposed a method to fabricate silver (Ag) resistance temperature detectors (RTDs) based on a blade-coating process directly on the surface of a quartz ring, which enables precise positioning and real-time temperature monitoring of tube furnaces within 100-600 °C range. The Ag RTDs exhibited outstanding electrical properties, featuring a temperature coefficient of resistance (TCR) of 2854 ppm/°C, an accuracy of 1.8% FS (full scale), and a resistance drift rate of 0.05%/h over 6 h at 600 °C. These features ensured accurate and stable temperature measurement at high temperatures. For demonstration purposes, an array comprising four Ag RTDs was installed in a tube furnace. The measured average temperature gradient in the central region of the tube furnace was 5.7 °C/mm. Furthermore, successful real-time monitoring of temperature during the alloy sintering process revealed approximately a 20-fold difference in resistivity for silver-palladium alloys sintered at various positions within the tubular furnace. The proposed strategy offers a promising approach for real-time temperature monitoring of tube furnaces.

Thermal Impedance Measurement of Thick-Film Resistor in High-Frequency Range Using Single-Detector IR System

This paper presents an innovative and simple method of high-frequency thermal impedance measurement using infrared (IR) technique. The method is based on the Fourier transformation of the input power signal and the thermal response of the object after supplying the heat source with square-wave current of different frequencies. The experiment was carried out using a single-detector, low-cost infrared system equipped with a photovoltaic detector module to measure the thermal impedance of an SMD thick-film resistor. Both the simulation using a compact thermal model and the measurement results are discussed.

High-Q Ku-band Microstrip Spiral Resonator in Fan-out Wafer-Level Packaging (FoWLP) Technology for VCO Applications

In this paper, a planar spiral resonator operating at 13 GHz is investigated. The resonator was fabricated using fan-out wafer level packaging (FoWLP) technology. The field analysis highlights the importance of via fence. Two thick film resistors suppress an undesired resonance in proximity of targeted one. The measurements demonstrate a very good correlation in comparison with full-wave simulations. The measured Q-factor defined based on analysis of feedback oscillatory system is about 48. The proposed configuration is suitable for voltage-controlled oscillators (VCOs) with a resonator realized in package.

Investigation of sensing performances of thick-film resistors sintered on fluorophlogopite glass-ceramic substrates

Strain gauges made of thick-film resistors (TFRs) offer a promising solution for monitoring the structural health of civil engineering projects, owing to their exceptional durability and stability. To address the issue of strain mismatch between alumina substrates and concrete materials, fluorophlogopite glass-ceramic (FGC), which has a low elastic modulus and good machinability, was utilized as a substrate for thick-film resistors. Compatibility between resistor pastes and substrates should be considered, as the substrate can significantly impact the performance of thick-film resistors. TFRs with varying concentrations of RuO2 were screen printed and fired at different temperatures on both FGC and 96% Al2O3 (as a control) substrates. The sheet resistivity, temperature coefficient of resistance (TCR), and gauge factor (GF) of TFRs were evaluated. The strain sensing performances of TFRs on FGC evaluated under compressive loading. The results indicate that TFRs on FGC substrates exhibit higher hot TCRs, lower sheet resistivities, and lower gauge factors than those on Al2O3 substrates under typical firing conditions of 850°C for 10 minutes. As the concentration of RuO2 increases, the differences in properties between TFRs on the two substrates become less pronounced. Microstructural analyses of the interface between the resistor layer and substrate indicate that changes in properties of TFRs on FGC substrates are primarily attributed to variations in RuO2 concentration and glass phase composition, which result from interactions between the resistor layer and FGC substrate. The interaction between the FGC substrate and the resistor layer can be significantly alleviated by lowering the firing temperature from 850°C to 750°C, resulting in TFRs on FGC substrates with properties comparable to those on alumina substrates. The TFRs on FGC exhibit favorable sensitivity, linearity, repeatability, and hysteresis within the input compression strain range of 0–3043με, thus showcasing significant potential for application in structural health monitoring (SHM) in civil engineering.

The effect of firing conditions on the characteris-tics of thick-film resistors for temperature sensors

The effect of firing conditions on the characteris-tics of thick-film resistors for temperature sensors

Fabrication and characterization of Screen-printed Graphite and Nickel Based Thick Film Resistive Strain Sensor

Piezo resistive properties of thick film resistors are shown by a variety of nanomaterials, in which graphite and nickel are used to study the piezo resistive response in this paper. The present work proposes to fabricate stain sensor on substrates like PVC, and transparent plastic sheet. Screen printing method is used for patterning of sensor on the substrates with two different inks namely piezo resistive ink made of graphite and nickel powder and conductive ink made of silver. Change in resistance of the fabricated sensor is noted for the changes in force applied on the sensor and corresponding gauge factor is observed to be around 10.5 and 11 for PVC and OHP respectively. The screen-printed strain gauge performance is investigated and presented in this paper. This study of mechanical test results demonstrate that the sensor can be used for micro strain detection in various applications.

Multi-functional phase for precision sampling resistors for HVDC voltage transformer and efficient microwave absorption

Precision resistor performance has a direct impact on the detection accuracy of DC voltage transformers since it is a crucial component for signal sampling in high-voltage DC (HVDC) voltage transformers. The accuracy of the resistance is directly related to the performance of the slurry, which is sintered to produce the resistance. In this article, two different kinds of conductive fillers carbon-based and metal-based were created using the hydrothermal technique and high-temperature carbonization, and the matching resistance slurry and thick film resistors were made by compounding glass powder and organic carriers. The findings demonstrate the resistance slurry prepared using copper nanopowder as a conductive filler can achieve lower square resistance values and can be adjusted within the range of 124 Ω/□ -1503 Ω/□ by changing the solid content, and the square resistance is less affected by temperature. It can be used as a precision resistor for preparing high-voltage DC voltage transformers. Furthermore, the prepared functional phase materials also exhibit satisfying microwave absorption performance. Typically, the copper nanopowder exhibits the RLmin of -23.77dB and the EABmax of 4.64GHz at 1.8mm. This work provides a reference for the application of functional phases in electronic slurry and microwave absorption fields.

QALIN QATLAMLI TEXNOLOGIYA ASOSIDA TAYYORLANGAN REZISTORLARNING PAST HARORATLARNI SEZMAYDIGAN TENZODATCHIK SIFATIDA QO‘LLANILISHI

A strain gauge made of thick-film resistors has a great potential for use in civil engineering owing to its relatively high voltage sensitivity, stability, low production cost, and long-term service capacities. However, a persistent drawback of strain gauges is their thermal sensitivity. To address this problem, it is advisable to propose and manufacture a strain gauge made of thick film resistors that do not sense low temperatures. This paper makes a close look into the effects of resistor paste components and baking temperature on the temperature coefficient of resistance (TCR) of a thick-film resistor. Thick film resistors made from RuO2 concentrations from 10 wt% to 30 wt% baked at different temperatures on an Al2O3 substrate, have been investigated. The relationship between resistor resistance, TCR and scale factor (GF) has been subject for studies. Findings show that TCR rises with an increase of the RuO2 concentration and baking temperature. Near the minimum (Tmin) of the resistance-temperature curve, the temperature has the least effect on the resistance value, and a thick-film resistor can be considered insensitive to temperature in a certain range. The ratio of TCR to GF and Tmin depends on the film resistance of thick film resistors. By varying the concentration of the conductive phase and the baking temperature, the film resistance of thick-film resistors can be controlled, and low-temperature strain gauges can be achieved for different ambient temperatures.

Influence of Gravity on Passively Cooled Heat Sink Using Experimental Data and Finite Element Analysis

This paper studies the effect of gravity orientation on a heat sink, used to passively cool a thick film resistor, by changing the assembly orientation. Using the same geometry and boundary conditions as in the experimental setup, finite element simulations were conducted to evaluate the accuracy of Siemens Flotherm XT 2021.2 simulation software. In order to determine the influence of heat sink orientation, experimental measurements were performed on the resistor and heat sink temperature using thermocouples. Siemens Simcenter Flotherm XT 2021.2 software (Siemens, Munich, Germany) was used to perform finite element simulation. The influence of the heat sink position was evaluated on two setups, one where the resistor is placed directly on the heat sink using screws, and the second one, where a thermal pad was placed between the resistor and the heat sink. Screws were to clamp the parts in both cases. In total, four experiments and simulations were performed with two assemblies with two different gravity orientations for each assembly. In all the cases, the heat sink was placed on a wooden structure to prevent heat transfer through conduction, due to poor thermal conductivity of wood, and to allow unrestricted air flow underneath and around the heat sink. The first simulation was then calibrated for the first scenario, and the rest of the simulations were made using the calibrated one. No other changes in boundary conditions were made. Temperature measurements show an improved cooling when the air speed between the heat sink fins is enhanced due to natural hot air movement generated by the gravity. Gravity has an influence on the cooling regardless of the presence or absence of a thermal interface material. Measured temperatures were reduced up to 8.2 °C due to the rotation of the heatsink. Finite element analysis shows similar temperature values to the measured ones in all the scenarios.

Application of extension rings in thermography for electronic circuits imaging

ABSTRACT Thermographic cameras are often used in areas, where resolutions below 100 µm per pixel are required, as for example in electronics. Such resolutions can be obtained using dedicated lenses. As an alternative, some manufacturers are offering extension rings to be added between the lens and the camera housing, to increase the final image spatial resolution. To test the latter solution and its impact on thermographic temperature measurements, a set of aluminium extension rings was manufactured and mounted in different combinations between an InSb cooled thermographic camera and its lens. Next, the camera, a blackbody IR source, a thick-film resistor on alumina substrate, a microscope reticle calibration glass, and two integrated test circuits were used to investigate the impact of the rings on the temperature measurement accuracy and the achieved spatial resolution. It was demonstrated, that extension rings are a very useful tool in thermography, as long as their impact on the measurement system is taken into account, considering numerical aperture reduction, rings heating by the operating camera, and the cold stop related vignetting. The impact will greatly depend on the specific design of the camera to be used and its lens configuration.

An investigation on magnetic properties and electrical resistivity of nanocrystalline CoFeNi thick films synthesized through stabilized bath

In this research, CoFeNi thick films were prepared through the electrodeposition process from a natural pH bath containing the complex agent of sodium citrate. By increasing applied current density, there is a transition from BCC (Fe) phase to BCC (Fe) + FCC (Co) phases and then to FCC (Co) phase. The XRD pattern showed a nanocrystalline structure for the CoFeNi thick films which was further confirmed by the TEM images. The magnetic properties of the synthesized magnetic films exhibit a noticeable decrease in the coercivity by decreasing the crystallite size which is consistent with the “D6” law. The resistivity of the CoFeNi thick films increased by decreasing the grain size which is due to the scattering of the charge carriers. The increase in the applied current density results in the gradual substitution of the iron atoms in CoFeNi films by nickel atoms leading to a reduction in saturation magnetization.

Design and characterization of Screen-Printed Piezoresistive Cantilever for Gas Sensor Application

In this paper, the design, and the characterization of screen-printed cantilever-based humidity sensor are described. The project investigated in detail the sensitivity, and fabrication process of screen-printing based sensor with coated active humidity material on cantilever’s free end. The main aim of this paper is to compare the screen-printed technology with other existing technologies like micro-electro-mechanical system (MEMS), and low temperature cofired circuit (LTCC). The sensor has been simulated under different level of relative humidity with two different temperature value: 35°C, and 45°C. This paper also represents an analytical and mathematical modeling approach for frequency shift and thick film resistance change of the selected sensor. The analytical results are compared with the simulated results.

The Effect of Co Content and Annealing Temperatures on the Resistivity in Ag-Co Films.

Ag-Co films with ultra-high resistivity were prepared on polyimide by magnetron sputtering. The effect of Co content and annealing temperatures on the resistivity and microstructure of Ag-Co films has been thoroughly investigated and the relation between resistivity and microstructure has been discussed. Results show that thicker Ag-Co films without annealing present lower resistivity due to better crystallinity. However, thin Ag-Co films (≤21 nm) annealed at 360 °C present ultra-high film resistivity because of the formation of diffusion pits on the film surface which blocks the transmission of electrons in films to increase film resistivity. Inversely, the resistivity of thick Ag-Co films (≥45 nm) annealed at 360 °C is much less than that annealed at lower than 260 °C owing to no diffusion pits. Furthermore, the addition of Co inhibits the growth of Ag grains and limits the migration of electrons in Ag-Co films further, also resulting in the increase of Ag-Co films’ resistivity.

Low temperature coefficient of resistance and high conductivity: Enhanced Cu–substituted LaCo0.4Ni0.6O3 ceramics for functional material

The LaCo0.4Ni0.6-yCuyO3 (LCNCu, y = 0.02–0.08) ceramics were prepared and their possibility as a cheap alternative functional material for thick film resistors was studied. Scanning electron microscopy, differential–thermal and thermomechanical analyses showed that the incorporation of Cu2+ lowered the densification temperature and enhanced the compactness of LCNCu ceramics. All of the samples revealed relatively high conductivity. When y < 0.05, both Cu2+ substitution and sintering temperature showed a strong influence on the conductivity of LCNCu ceramics. However, the simulation results indicated that the density of states almost did not change after Cu2+ substitution despite the weakened electron transport. The temperature coefficient of resistance (TCR) gradually decreased with the addition of Cu2+. Low TCR values (absolute values < 300 ppm/°C) and high conductivity were realized for the samples with y ≤ 0.04 sintered at 1200 °C and y = 0.02 sintered at 1225 °C. Consequently, the improved LaCo0.4Ni0.6-yCuyO3 ceramics may be a potential economical functional material for thick film resistors.

Improved Nb–substituted La0.5Sr0.5CoO3 ceramics as new and low–cost functional materials for thick–film resistors

The use of ruthenium oxides as a functional material for commercial thick–film resistors is not conducive to further lowering manufacturing costs. In this study, we propose Nb–substituted La0.5Sr0.5CoO3 (La0.5Sr0.5Co1-yNbyO3, LSCNb, y = 0.02–0.08) ceramics as new and low–cost functional materials for thick–film resistors. The conductivity and temperature coefficient of resistance (TCR) of the LSCNb samples sintered at different temperatures displayed similar downward trends with increasing Nb5+ content. A relatively high conductivity of 1670 S/cm and a minimum absolute TCR of −168 ppm/°C were attained for the sample with y = 0.06 sintered at 1225 °C. Furthermore, zero TCR was achieved for samples within the doping range of 0.05 < y < 0.06. The variation in density of states, electron density, and bond population could explain the change in electrical properties in the experiment. Additionally, the LSCNb ceramics showed good frequency stability. Therefore, the improved Nb–substituted La0.5Sr0.5CoO3 ceramics can be promising candidates for low–cost functional materials of thick–film resistors.

Recent Advances in Thick-Film Resistors and Target Applications [Passive Components

Thick-film resistors are the preferred resistor type for a wide range of industrial and consumer applications, including current detection and overvoltage protection, due to their relatively low cost. Unlike thin-film resistors, which are similar in appearance, thick-film resistors have contrasting properties and manufacturing processes. And, as their names imply, another key difference between the two is their thickness. While thin-film resistors measure up to a maximum of 0.1 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> m, the thickness of thick-film resistors can be 0.1 mm or more. The ever-present need for low power consumption and circuit protection in relevant applications is driving the demand for high-performance thick-film resistors. This article gives an overview of thick-film resistors, noting some recent advances and the applications they address.

Study of New Nitrogen-Fireable Copper-Nickel Thick Film Paste Formulation Compatible with Thick Printed Copper.

This paper is focused on a new copper-nickel thick film resistive paste which was designed and experimentally developed for the realization of low-ohmic power resistors. This copper-nickel paste has been designed for use in combination with thick printed copper conductors and in comparison with conventional ruthenium-based thick film resistor pastes allows firing in a nitrogen protective atmosphere. The copper-nickel paste was prepared from copper and nickel microparticles, glass binder particles and a combination of organic solvents optimized for its firing in a nitrogen atmosphere. This paper covers a detailed description of copper-nickel paste composition and its thermal properties verified by simultaneous thermal analysis, a description of the morphology of dried and fired copper-nickel films, as well as the electrical parameters of the final printed resistors. It has been proven by electron microscopy with element distribution analysis that copper and nickel microparticles diffused together during firing and created homogenous copper-nickel alloy film. This film shows a low temperature coefficient of resistance ±45 × 0−6 K−1 and low sheet resistance value 45 mΩ/square. It was verified that formulated copper-nickel paste is nitrogen-fireable and well-compatible with thick printed copper pastes. This combination allows the realization of power substrates with directly integrated low-ohmic resistors.

Firing variables and strain sensitivity of Bi2Ru2O7 thick resistive films

In order to provide accurate and semi-real-time information about performances and conditions of various civil engineering structures thick-film resistors are often being used as strain sensors. For that purpose, Ba2Ru2O7 thick resistive films based on compositions with sheet resistivities of 1 kOhm/sq, 10 kOhm/sq and 100 kOhm/sq were evaluated. Resistors were fired at three different peak temperatures (825oC, 850oC and 875oC) and with three different dwelling times (5 min, 10 min and 15 min) in order to correlate influence of firing variables and thick resistive film strain sensitivity by tracking structure-related changes in resistance, gage factor and noise index values. For 10 kOhm/sq composition values of resistance change vs. temperature and temperature coefficient of resistance were measured and calculated.