Search results

1 – 10 of 497
Article
Publication date: 5 May 2015

Busi Rambabu and Y. Srinivasa Rao

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…

Abstract

Purpose

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.

Design/methodology/approach

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.

Findings

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

Research limitations/implications

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

Practical implications

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.

Originality/value

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.

Details

Microelectronics International, vol. 32 no. 2
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 29 April 2014

Kandagaddla Venkatasubrahmanayam, Busi Ram Babu, Billa Poornaiah and Yarravarapu Srinivasa Rao

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…

Abstract

Purpose

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.

Design/methodology/approach

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.

Findings

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

Research limitations/implications

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

Practical implications

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.

Originality/value

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.

Details

Microelectronics International, vol. 31 no. 2
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 2 January 2007

Y. Srinivasa Rao

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…

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.

Details

Microelectronics International, vol. 24 no. 1
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 7 June 2019

Janusz Borecki, Aneta Araźna, Kamil Janeczek, Jerzy Kalenik, Michał Kalenik, Wojciech Stęplewski and Rafał Tarakowski

Nowadays, using of material properties for monitoring of phenomena occurring in the surrounding environment is very desirable. Taking into account the dynamic development…

Abstract

Purpose

Nowadays, using of material properties for monitoring of phenomena occurring in the surrounding environment is very desirable. Taking into account the dynamic development of Internet of Things and the technological development of printed electronics, research into the using of printed electronic components for sensor applications can be one of the most prominent directions of searching for new innovative solutions. Among others, it is possible to apply them to produce the strain gauges, as well as for construction of advanced sensors for medical applications. The goal of this paper is to present the possibilities and using different constructions of embedded polymer thick-film resistors as the sensors of tension or strain.

Design/methodology/approach

The investigations were based on the polymer thick-film resistors made of carbon or carbon–silver inks printed on copper pads made on FR-4 material on two sides. The longitudinal samples laminated with resin-coated copper foil material and without lamination were bent on a strength machine. During the tests, the resistors depending on their placement were stretched or compressed. Some of the samples were also tested under high pressure. Under the influence of applied stresses, there was a reversible change in electrical resistance, which was monitored.

Findings

The study showed that the polymer thick-film resistors are characterized by a measurable piezoresistive effect. By analyzing the value of the observed resistance changes, a magnitude of strain or pressure can be worked out. During the bending, the piezoresistive effect depends on the location and orientation of the resistor. After stopping of the mechanical strains, the electrical resistance of the resistive elements does not return exactly to the initial value. This is probably related to the substrate material and the resistive paste composition. The results are very promising and further research will be done.

Originality/value

The results provided information about the piezoresistive effect of polymer thick-film resistors printed on the deformable substrate which could be interesting for engineers involved in printed sensor development dedicated for different fields of application. This phenomenon can be used to manufacturing cheap and uncomplicated sensors to monitor deformation. There are several aspects to be solved, but with the use of new types of resistive pastes and substrates, there is a potential possibility of using such resistors as sensors.

Details

Circuit World, vol. 45 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 1 February 1985

A. Kabe and I. Morooka

Polymer thick film circuits have been used in consumer appliances, a trend that is growing as one of the major technologies in Japan in this field. This paper discloses…

Abstract

Polymer thick film circuits have been used in consumer appliances, a trend that is growing as one of the major technologies in Japan in this field. This paper discloses the state of the art of the processes involved along with the main features of the circuits. PTF has established a performance that equals that of the cermet type in some applications, which produces cost advantages for PTF circuits on polymer and/or ceramic substrates for wider applications.

Details

Microelectronics International, vol. 2 no. 2
Type: Research Article
ISSN: 1356-5362

Article
Publication date: 1 December 2003

Y. Srinivasa Rao and M. Satyam

This paper deals with the investigations carried out on the variation of current noise (1/f noise) in polymer thick film resistors, when they are subjected to pulse…

Abstract

This paper deals with the investigations carried out on the variation of current noise (1/f noise) in polymer thick film resistors, when they are subjected to pulse voltage trimming. The current noise is measured in terms of noise index (micro volts of noise per volt of DC applied, in a decade of frequency) using Noise Meter Model 315 C manufactured by Quan‐Tech of New Jersey. It has been found that current noise decreases as the resistors are trimmed to lower values. An attempt has been made to explain the decrease in current noise with the trimming of resistors.

Details

Microelectronics International, vol. 20 no. 3
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 1 August 2002

Y. Srinivasa Rao and M. Satyam

The effects of material parameters and processing conditions on the resistance drop by high voltage discharge in PVC – graphite thick film resistors are studied in this…

Abstract

The effects of material parameters and processing conditions on the resistance drop by high voltage discharge in PVC – graphite thick film resistors are studied in this paper. The resistance drop increased upon an increase in graphite aggregate size, which is a function of material parameters and processing conditions. The resistance drop has been attributed to the dielectrophoretic motion of graphite particles in PVC by the application of high voltages to polymer thick film resistors.

Details

Microelectronics International, vol. 19 no. 2
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 1 August 2003

Y. Srinivasa Rao and M. Satyam

The effect of high voltage pulses on the resistance of polymer thick film resistors (PTFR) is studied. It is found that the resistance decreases with both the amplitude…

Abstract

The effect of high voltage pulses on the resistance of polymer thick film resistors (PTFR) is studied. It is found that the resistance decreases with both the amplitude and duration of the high voltage pulses and with the number of pulses. The change in resistance is attributed to the dielectrophoretic motion of graphite granules in the PVC medium when high voltage pulses are applied to PTFR. A model has been proposed through which the percentage change in resistance can be estimated in terms of the number of pulses, duration of pulses etc. Based on these investigations, we suggest a downward trimming method for PTFR through the application of high voltage pulses. This method of trimming is a clean process and trimmed resistors are free from hot spots.

Details

Microelectronics International, vol. 20 no. 2
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 1 February 2016

Paweł Osypiuk, Andrzej Dziedzic and Wojciech Stęplewski

The purpose of this paper is to determine the influence of mechanical factors (such as longitudinal elongation or cyclic compressive and tensile stresses) on electrical…

Abstract

Purpose

The purpose of this paper is to determine the influence of mechanical factors (such as longitudinal elongation or cyclic compressive and tensile stresses) on electrical properties of thin- or thick-film resistors or conductors.

Design/methodology/approach

All test samples were made on Kapton foil. Copper foil or silver-based polymer thick-film conductive inks were used for fabrication of conductors. Resistive structures were made with the aid of two polymer thick-film resistive inks or OhmegaPly Ni-P resistive foil. Test structures differ not only in materials applied for resistors or conductors but also in geometrical shape of functional tracks (meanders consisted of many horse-shoes, semicircles, squares or triangles).

Findings

Presented results showed significant role of material on range of reversible resistance changes. But shape of test samples also affects relation between relative resistance changes and relative elongation.

Originality/value

In general, changes induced by cyclic compressive and stretching stresses were smaller than those caused by substrate elongation.

Details

Soldering & Surface Mount Technology, vol. 28 no. 1
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 6 February 2017

Wojciech Steplewski, Andrzej Dziedzic, Janusz Borecki and Tomasz Serzysko

The purpose of this paper is to investigate the basic functional parameters of passive embedded components in printed circuit boards (PCBs) under environmental exposures…

198

Abstract

Purpose

The purpose of this paper is to investigate the basic functional parameters of passive embedded components in printed circuit boards (PCBs) under environmental exposures such as thermal-humidity and thermal exposure.

Design/methodology/approach

The investigations were based on the thin-film resistors made of NiP alloy, thick-film resistors made of carbon or carbon–silver inks, embedded capacitors made of FaradFlex materials and embedded inductor made in various configurations. The capacitors and thin- and thick-film resistors were tested in the climatic chamber in conditions of thermal-humidity exposure at 85°C and 85 per cent RH for 500 h. The embedded inductors were tested in two different environmental conditions: thermal-humidity exposure at 60°C and 95 per cent RH, and thermal exposure at 150°C and additionally at the temperature in the range of +25°C to +150°C.

Findings

Studies show that in the case of embedded capacitors, the changes caused by exposure to thermal-humidity are durable and lead to the capacity increase. The embedded thin-film resistors behave in the same manner, whereas the thick-film resistors were the least resistant to the conditions of exposure. Most of the polymer thick-film resistors have been damaged. The changes of coils' properties during aging are small, and what is most important is that, after some time of exposure, their parameters stabilize at a particular level. The changes resulting from the increase in temperature are typically related to the change of material resistance (Cu) of which coils are made, and as such, they cannot be avoided but they can be predicted.

Research limitations/implications

The realized studies allowed determination of the properties of the embedded passive elements with respect to specific environmental exposures. The studies show that embedded resistors can be used interchangeably with chip passive elements. It allows saving the area on the surface of PCB, occupied by these passive elements, for assembly of active elements integrated circuits (ICs) and thus enabling the miniaturization of electronic devices.

Originality/value

The knowledge about the behavior of the operating parameters of embedded components, considering the environmental conditions, allows for development of more complex systems with integrated PCBs.

1 – 10 of 497