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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.

New resistor compositions prepared by using special kinds of glass, CdO, RuO2 and Nb2O5, have been developed. This system is typical in containing only a small amount of RuO2, ranging from 2 wt% to 8 wt%. The properties of resistors prepared from various compositions were tested in relation to peak firing temperature varying in the range from 720°C up to 800°C. In this way conditions were found for resistor preparation with low TCR and high long‐term stability at 95% relative humidity and at 40°C. By adding very small amounts (0·4–0·9%) of Nb2O5 the TCR was very drastically reduced and could achieve almost zero value. The resistance changes after 4,000 hours ranged from 0·1% to 0·8%. Further new types of dielectric compositions were prepared. The bulk insulation resistance of fired layers reached values in the range of 1012ohms/cm2; the dielectric constant (≈7) and dissipation factor (≈10−3) were also measured. This composition is well suited to applications in both oxidation and inert atmosphere.

Copper substrates covered with ceramic insulating coating were tested for their ability to be used in thick film technology. The ceramic coating was prepared by screen printing from a dielectric composition containing special glass and aluminium oxide and was fired at 820°C–1,000°C. The electrical properties of the coatings studied included voltage breakdown, surface and bulk insulation resistance and dielectric constant. Resistor compositions designed for use on ceramic substrates were screen printed, as on the substrates mentioned, on alumina or ceramic‐coated steel substrates and fired up to the required temperatures (820–875°C). The resistivity and TCR of the prepared resistors were measured in relation to firing temperature. The distribution of lead, bismuth, ruthenium, barium, palladium, silver and copper in the system resistor (or conductor) ceramic coating/copper substrate was investigated. Reference was made to the application of ceramic coatings on copper in other fields, e.g., in heavy‐current electronics.

For thick film resistor materials with low sheet resistivity (less than 10 ohm/□) sheet resistivity increases with decreasing resistor length, when terminated with Pd alloy based conductors. This is due to the reaction of palladium from the thick film conductor and bismuth ruthenate (Bi2Ru2O7), which is the active phase in thick film resistor material. The experimental results indicate the formation of Pd/Bi solid solution on the interface between the conductor and resistor. Because of its higher specific resistivity, this layer functions as an additional source of resistivity.

Dates: 23–24 March 1994 Venue: Palais des Congrès, Porte Maillot, Paris The Fifth Microelectronics Salon (Hybrids, SMT, ASICs, Packaging) will take place on the above dates. This showcase for manufacturers, suppliers of products and equipment, and sub‐contractors to all sectors of these industries will be accompanied by a series of conferences.

The growth in digital telecom systems around the world has led to an increase in demand for surge protection components. These components often use low ohm resistor compositions in a serpentine configuration. The demands placed upon these materials during pulsing are high. Not only are the materials expected to withstand more severe pulses, they are also expected to have minimal adverse effect on the environment. To meet these increased demands, a new system of surge resistor materials has been developed. The design, manufacture and testing of these materials ensures optimum performance in high voltage surge applications. This paper describes the performance of this new surge resistor system and discusses how the performance of the resistors relates to the paste constituents, encapsulant materials and the laser trimming process.

The purpose of this paper is to study the microwave interactions in polymer thick film resistors, namely, polyvinyl chloride (PVC)-graphite thick film resistors, and its applications in trimming of these resistors.

We applied microwave radiation in the form of pulses of various pulse durations and with different powers to polymer thick film resistors and observed the variation of resistance of these resistors with microwave radiation.

The paper finds that microwave radiation can be used for trimming of polymer thick film resistors.

The research implication of this paper is that polymer thick film resistors can be trimmed practically using this method.

The practical implication of this paper is that we can trim the polymer thick film resistors, namely, PVC-graphite thick film resistor, by using this method.

The value of the paper is in showing that microwave radiation can be used to trim downwards in the case of high-value resistors and trim upwards in the case of low-value resistors.

The purpose of this paper is to present the properties of thick-film resistors made of novel pastes prepared from glass and graphite.

Graphite-based resistors were made of thick-film pastes with different graphite-to-glass mass fraction were prepared and examined. Sheet resistance, temperature coefficient of resistance, impact of humidity and short-term overload were investigated. The properties of the layers fired in atmospheres of air at 550°C and nitrogen at 875°C were compared.

Graphite-based resistors with various graphite-to-glass ratios made possible to obtain a wide range of sheet resistance from single O/square to few kO/square. These values were dependent on firing atmosphere, paste composition and the number of screen-printed layers. The samples made of paste with 1:1 graphite-to-glass ratio exhibited the temperature coefficient of resistance of about −1,000 ppm/°C, almost independently on the firing atmosphere and presence of a top coating. The resistors fired in the air after coating with overglaze, exhibited significantly lower sheet resistance, reduced impact of humidity and improved power capabilities.

In this paper, graphite-based resistors for applications in typical high-temperature cermet thick-film circuits were presented, whereas typical graphite-based resistors were fabricated in polymer thick-film technology. Owing to very low cost of the graphite, the material is suitable for low-power passive circuits, where components are not subjected into high temperature, above the typical temperature of operation of standard electronic components.

The paper aims to study the variation of electrical properties like electrical resistivity and current noise of a polymer thick film resistor, namely, PVC‐graphite thick film resistor, with parameters such as volume fraction, grain size, temperature and high voltage.

A model is proposed to explain the observed variations, which assumes that the texture of the polymer thick film resistor consists of insulator granules coated with conducting particles and also having cavities. The resistivity of these resistors is controlled mainly by the contact resistance between the conducting particles and the number of contacts each particle with its neighbors.

The variation of resistivity with temperature and high voltage is explained with the help of the model and it is attributed to the change in contact area and number of contacts. The current noise of these resistors is controlled mainly by the average relative resistance fluctuations between the conducting particles and the number of contacts each particle with its neighbors.

The variation of current noise with high voltage has also been explained with the help of this model and it is attributed to the change in number of conducting particles and conducting layers.

The purpose of this paper is to study high-voltage interactions in polymer thick-film resistors, namely, polyvinyl chloride (PVC)-graphite thick-film resistors, and their applications in universal trimming of these resistors.

The authors applied high voltages in the form of pulses and impulses of various pulse durations and with different amplitudes to polymer thick-film resistors and observed the variation of resistance of these resistors with high voltages.

The paper finds that high voltages can be used for trimming of polymer thick-film resistors in both directions, i.e. upwards and downwards.

The research implication of this paper is that polymer thick-film resistors can be trimmed downwards or upwards practically using this method.

The practical implications of this paper is that one can trim the polymer thick-film resistors, namely, PVC–graphite thick-film resistors, in both directions, i.e. upwards and downwards, by using this method.

The value of the paper is in showing that high voltages can be used to trim downwards and also upwards in the case of polymer thick-film resistors. This type of trimming is called universal trimming, developed first time for polymer thick-film resistors.