Studies on electrical properties of polymer thick film resistors

Abstract

Purpose -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. Design/methodology/approach -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. Findings -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. Originality/value -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 effect of microwave radiation on polyvinyl chloride-graphite thick film resistors

“…This paste has been used for printing resistor on PVC substrates with a screen printer. These printed resistors are processed using thick film processing of polymer-based films (Srinivasa Rao, 2007;2008;Prathap Kumar and Srinivasa Rao, 2009). The heat treatment involves drying at room temperature for 15 minutes, followed by curing at 100°C for 4 hours.…”

“…Trimming of cured polymer thick film resistor forms an integral part of polymer thick film technology (Srinivasa Rao, 2007;2008;Prathap Kumar and Srinivasa Rao, 2009). Currently, polymer-based pastes are used to fabricate resistors for economical reasons.…”

Studies on temperature coefficient of resistance (TCR) of polymer thick film resistors

“…The author (Srinivasa Rao, 2007) has expressed the resistance R s of the elemental cell of the composite material as:…”

“…The author (Srinivasa Rao, 2007) has expressed the resistance R s of the elemental cell of the composite material as: Equation 3 where R S – resistance of the elemental cell; R 0 – contact resistance between two conducting particles; V f – volume fraction of conducting phase; K – constant of the material and is given by the following equation: Equation 4 where D = diameter of the conducting particle.…”

Studies on the Percentage Variation of Resistance of PVC-Graphite Thick Film Resistors

“…From the previous studies of the authors (1)(2)(3)(4) , it is known that the mixtures of graphite and PVC can be utilized as thick film resistors. Their electrical properties such as sheet resistivity, current noise and TCR have been obtained and studied.…”