Evolution of the Microstructure and Performance of Pd/Ag - Based Thick Conductors

Pd/Ag-based inks are probably the most commonly used conductors in thick-film hybrid technology. The evolution of the microstructure of these films was studied on samples fired with isochronal cycles at a peak temperature in the range from 300℃ up to 850℃. The samples were investigated by means of X-ray diffraction, SEM and EDAX analysis techniques; the results of these analyses as well as those of thermogravimetry (TG, DTG) and differential thermal analysis (DTA), enable one to obtain a clear picture of the complex evolution of the microstructure of these conductors, which correlates quite strictly with the performance of the films in terms of resistivity and adhesion

Superconducting Thick-Films From a Y-Ba-Cu-O Precursor

We have prepared screen-printed films of the Y-Ba-Cu-O compound starting from a spray-pyrolysis precursor powder. BeO ceramic substrates are confirmed to be inert with respect to the film up to about 1000ºC. Electrical properties of oxygen annealed films are investigated, evidencing excellent superconducting behaviour, both in terms of Tc(≃91K) and Jc (>102 A.cm-2 at 77 K)

Piezoresistive effects in thick film resistors: 30 years after

The most successful applications of thick film materials in the sensor area rely on piezoresistive effects exhibited by thick film resistors (TFRs). The earliest evidence of strain sensitivity in TFRs was available in 1973, but its value for thick film strain gauges was not recognized. A few years later attention was drawn on the peculiar set of properties that make TFRs valuable for the implementation of new classes of sensors for strain-related phys. quantities. Since then, piezoresistive properties of TFRs have attracted a great deal of scientific and technological interest and applications have rapidly spread for many diversified areas. Advances in knowledge accumulated in recent years on the properties of thick film piezoresistors are reviewed, in connection with resistive-paste composition, processing and film's micro-structure. Recent theoretical work is also mentioned: taking into account the segregated microstructure of TFRs, this work emphasizes how these piezo-resistive effects are related to this unique type of metal-insulator composites

Localized states in different samples of beta-rhombohedral boron

The activation energy and relative concentration of localized states in beta-rhombohedral Boron obtained from several sources were studied by transient photoconductivity, space-charge-limited currents, thermally stimulated currents, and thermally stimulated depolarization currents. Activation energies for electron traps are 0.25 and 0.44 eV, and for hole traps, the activation energies are 0.23 and 0.36 eV. The differing location and density of localized states suggests that they are extrinsic in nature

Other sensors, actuators and ancillary parts for measuring systems.

A review, with 20 references. Previous sections in the book considered the major areas where thick film technology and materials were systematically studied for sensors applications. However a variety of minor themes (of interest for control systems and instrumentation) only marginally addressed, deserves a mention. Also thick-film components can play a significant role in sensors and actuators, even if they can not be defined as sensing elements. Examples of these matter are presented

Characterization of pyrolytic boron films

The transport mechanisms of pyrolytic B films were elucidated in order to study the characteristics of boron thermistors. Boron films were deposited thermal decomposition of BCl3 and H2 onto Mo (wires or sheets) of insulating (quartz) substrates. Electrical properties were studied for films in the thermistor structure with a layer bonded between two Mo crossed wires that formed electrical contacts, or films on quartz. The electrical conduction of the pyrolytic films was 7 × 10-5-10-6 Ohm-1 cm-1. An equation for the linear temperature dependence of the electrical conductivity is given for the temperature range 60-800 K. The thermoelectric power of the pyrolytic boron film was positive in the order 100 µV K-1 at 300 K. No appreciable photoconductiviy was observed. The results suggest that thermally activated hopping is the dominant transport mechanism in pyrolyic boron film. This film is superior to the crystalline or amorphous forms for the thermistor preparation

Thick film tecknology

This paper outlines the continuous progress of thick-film technology in providing a valuable means for the manufacture of solid-state sensors in three major areas of applications: hybrid circuits for signal processing, creation of structures upon which sensing materials can be added to provide new forms of sensors and thick-film materials able to offer suitable transducing properties. It is stressed here that while the technology proceeds apace, the material science of thick-film sensors requires greater research efforts

Force measurement device for controlling the position of an implement for towing by an agricultural machine

A force measuring device for an implement for towing an agricultural machine comprising at least one connection arm between the implement and a flexure bar mounted on said agricultural machine, at least one lever connecting the arm to a control system, wherein said control system comprises an electrical circuit arranged to control the movement of the lever by means of a mechanical and/or hydraulic member, the electrical circuit comprising at least one resistive element fixed to a portion of the flexure bar, the resistive element being constructed of a material the resistance of which is proportional to the deformation which the element undergoes when in use

Thick film resistors

A review with 42 references. Thick film resistors (TFRs) play a relevant role in sensor technology. They are essential elements of thick-film hybrid circuits for sensor signal conditioning as well as sensing elements. The general features of TFRs are given in terms of composition, microstructure and characteristics of performance