Commercial Thick-film Resistors Research Articles

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.

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.

The application of thick-film technology in C-MEMS

Laminated 3D structures made using low-temperature co-fired ceramic (LTCC) technology are practical for ceramic micro-electro-mechanical systems (C-MEMS). The sensors for mechanical quantities, and/or actuators, are fundamental parts of MEMS. Thick-film resistors can be used to sense the mechanical deformations, and thick-film piezoelectric materials can be used as electro-mechanical transducers in a C-MEMS structure. The integration of these thick-film materials on LTCC substrates is in some cases difficult to realise due to interactions with the rather glassy LTCC substrates. The subject of our work is an investigation of thick-film materials for electro-mechanical transducers (sensors and actuators) and their compatibility with LTCC substrates. Resistors made with commercial thick-film resistor materials for use as sensors on LTCC substrates have been investigated and evaluated. Ferroelectric ceramic materials based on solid solutions of lead zirconate titanate (PZT) with low firing temperatures around 850°C were developed for thick-film technology and evaluated on LTCC substrates.

Characteristics of thick film resistors embedded in low temperature co-fired ceramic (LTCC) substrates

Commercial thick film resistors were embedded in low temperature co-fired ceramic (LTCC) substrates, and co-fired with substrates at temperatures between 800 and 900 °C. Adding glass frit and amorphous SiO 2 to calcium borosilicate glass ceramic substrates has not only lowered the shrinkage of the substrates, but also improved adhesion and maintained structure integrity of the resistor films. During sintering, the conductive phase particles in the resistor became agglomerated and sedimented, and glass diffused into the LTCC substrate layer. Increasing the dwelling time, the overall resistivity of the co-fired films decreased due to sedimentation of agglomerated conductive particles. The liquid eutectic phases penetrated into the substrates added with either SiO 2 or glass frit that the volume fraction of conductive particles was increased. The resistivity of the embedded resistors was determined by the volume fraction of conductive particles, which was influenced by the conductive particles sedimentation, microstructure of resistor films, and inter-diffusion between the resistors and substrates.

High-strain response of piezoresistive thick-film resistors on titanium alloy substrates

We examine, in this work, the integration and high-strain response of piezoresistive thick-film resistors on titanium and titanium alloy, as compared with ferritic stainless steel and the standard alumina substrates. In general, titanium and its alloys are relatively ill suited for use as a thick-film substrate using the standard 850 °C firing process, because of its low oxidation resistance and tendency to dissolve oxygen. This problem can be alleviated by applying suitable thick-film glassy protection layers. Titanium alloys are very elastic, and allow piezoresistive responses well in excess of 4% with little plastic deformation of the substrate, using standard commercial thick-film resistor compositions. In this case, the behaviour of the sensor becomes asymmetric, as failure of the resistor or insulating dielectric under tension—and therefore the mechanical properties of these materials—becomes the factor limiting the response of the sensor.

Properties of Ruthenia-Based Resistors Embedded in Low-Temperature Co-Firable Ceramic Substrates

Commercial thick-film resistor pastes were printed on and embedded in cordierite+borosilicate glass low-temperature co-firable ceramic (LTCC) substrates. The electrical properties of the resistors were found to depend on the final microstructure. Anorthite crystals were produced by the interaction between the substrates and glass composition of the resistor films at boundaries. The anorthite crystals grown into the substrate and the resistor layer increased the overall resistance. Sedimentation of the conductive particles and glass migrating to the substrates decreased the resistor thickness during sintering. Conductive particles in the resistor films flocculated after firing at 850° and 900°C. Formation of anorthite crystals, conductive particle sedimentation, glass migration, and inter-diffusion were determined to be three major factors determining film resistivity.

A characterisation of thick film resistors for strain gauge applications

Some commercial thick film resistors with sheet resistivities from 1 kohm/sq. up to 1 Mohm/sq. were evaluated for strain gauge applications. Temperature coefficients of resistivity, noise indices and gauge factors (GFs) were measured. For the same resistor series GFs and noise indices increase with increasing sheet resistivity. However, both GFs and noise indices are different for resistors with the same nominal sheet resistivity but from different resistor series. The results indicated that the microstructure rather than the different chemical composition of the conductive phase in thick film resistors is the primary reason for the different gauge factors.

Thick-film resistive temperature sensors

This paper discusses thick-film resistive temperature sensors investigated at the Technical University of Wroclaw. The technology and electrical properties of resistance temperature detectors, thermistors, low-temperature thermometers and heating elements are presented. The R(T) curve of chosen air-fireable Ni - P based films agrees with Ni wire. The initially aged thermistors from the system can operate in the range from room temperature up to 673 K. The commercial thick-film resistors modified by the negative TCR drivers (e.g. powder) are fully suitable for low-temperature measurements in the range from 20 to 100 K. The integrated gas sensors need heaters because temperature influences their sensitivity, selectivity and response time. The thick-film compatible system based on commercially available resistive and conductive inks allows continuous long-term electrical heating of the sensor up to 673 K. The admissible operating temperature is much higher for the heaters made from conductive inks; for example fritless platinum heaters are satisfactory up to 1073 K.

Thick-film resistor/dielectric interactions in a low temperature co-fired ceramic package

Various commercial thick-film resistors are processed with a low temperature co-fired ceramic (LTCC) packaging material. The electrical properties and microstructure of the resistors are correlated. Three types of resistor/dielectric interfaces are observed. The interactions that occur between the resistor and the dielectric during the co-sintering process are affected by the physical and chemical properties of the glass phase of the resistor material. These interactions between the resistor and the dielectric are kinetically controlled by glass flow at the sintering temperature and thermodynamically driven by the activity gradients between components in the glass phases. The effect of these interactions on the sheet resistance and temperature coefficient of resistance of the resistor materials are discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

An evaluation of some commercial thick film resistor materials for strain gauges

An evaluation of some commercial thick film resistor materials for strain gauges

Simple and inexpensive cryogenic bolometers

Simple and inexpensive low-temperature bolometers have been fabricated using commercial thick-film resistors. The bolometer resistance depends both on the temperature and on the bias voltage. The responsivity and time constant are deduced in this non-ideal case.

Conduction mechanism in granular Ru0 2-based thick-film resistors

The conductivity of a commercial thick-film resistor is measured between 4 K and 15 mK and in magnetic fields up to 7 Tesla. The data can be described by the variable-range hopping mechanism with a Coulomb gap in the density of states. The negative magnetoresistance may be attributed to quantum-interference effects in the strongly localized regime.

The ageing behaviour of commercial thick-film resistors: Nihal Sinnadurai and Keith J Wilson IEEE Trans. Components Hybrids mfg Technol. CHMT-5 (3), 308 (1982)

The ageing behaviour of commercial thick-film resistors: Nihal Sinnadurai and Keith J Wilson IEEE Trans. Components Hybrids mfg Technol. CHMT-5 (3), 308 (1982)

The ageing behaviour of commercial thick-film resistors: Nihal Sinnadurai and Keith J. Wilson IEEE Trans. Components Hybrids mfg Technol. CHMT-5 (3), 308 (1982)

The ageing behaviour of commercial thick-film resistors: Nihal Sinnadurai and Keith J. Wilson IEEE Trans. Components Hybrids mfg Technol. CHMT-5 (3), 308 (1982)

The ageing behaviour of commercial thick-film resistors: Nihal Sinnadurai and Keith J. Wilson IEEE Trans. Components Hybrids mfg Technol. CHMT-5 (3), 308 (1982)

The ageing behaviour of commercial thick-film resistors: Nihal Sinnadurai and Keith J. Wilson IEEE Trans. Components Hybrids mfg Technol. CHMT-5 (3), 308 (1982)

The ageing behaviour of commercial thick-film resistors : Nihal Sinnadurai and Keith J. Wilson. IEEE Trans. Components Hybrids mfg Technol.CHMT-5 (3), 308 (1982)

The ageing behaviour of commercial thick-film resistors : Nihal Sinnadurai and Keith J. Wilson. IEEE Trans. Components Hybrids mfg Technol.CHMT-5 (3), 308 (1982)

The Aging Behavior of Commercial Thick-Film Resistors

An earlier paper reported the promising prospects of accelerating thick-film resistor aging by elevated temperature and humidity stress; those early findings have now been confirmed by further results from many thousands of hours of overstress testing of commercially produced resistors from various sources--amounting to accumulated test times of some millions of resistor-hours. The normal aging trend is a steady increase in resistance at a rate influenced by various factors such as manufacturing origin, resistivity, electrical bias, environment, and encapsulation. The majority of the increases vary with the square-root of time, consistent with a diffusion-controlled degradation of the conduction processes. Some changes also conform to piezo-resistive effects and together these provide physical explanations for the aging behavior of thick-film resistors. The drift observed in the majority of resistors can be extrapolated to give a prediction of less than 0.5 percent change in 20 years operation in standard environments---a heartening prospect indeed for thick-film reliability.