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Article
Publication date: 1 March 1993

M. Hrovat, D. Belavič and A. Markošek

The direct overlapping of thick film NTC thermistors and resistors was attempted to enable the trimming of NTC thermistors to relatively narrow tolerances with little…

Abstract

The direct overlapping of thick film NTC thermistors and resistors was attempted to enable the trimming of NTC thermistors to relatively narrow tolerances with little influence on beta factors. Different combinations of 1 kohm/□ thick film NTC material (4993, Remex) and 1 and 10 kohm/□RuO2 and ruthenate based thick film resistors (HS‐80 series, Du Pont), fired either together or separately, were tested. The sheet resistivities, TCR and beta factors of these combinations were measured. Microstructures were investigated by SEM and analysed by EDS. The results, i.e., the large decrease of sheet resistivities (up to ten times) and a resistivity vs. temperature dependence which changed from negative to positive TCR for some combinations, indicate the interaction between NTC materials and resistors during the firing process. These interactions are more distinctive for materials fired together. In all cases the beta factors were lower than calculated. Based on these experiments, the ‘best’ thick film resistor paste for NTC/resistor combination (HS‐8041, Du Pont) was chosen. Several layouts with partially or entirely overlapped NTC thermistors/resistors were designed. Unprotected, glass protected or organic protected circuits were laser trimmed. The resistivities and beta factors were measured as a function of resistor geometries and laser cut lengths. The results obtained demonstrated that NTC thermistors, partially overprinted with an ‘ordinary’ thick film resistor, can be trimmed to tolerances around 0.5% without any special precautions during trimming.

Details

Microelectronics International, vol. 10 no. 3
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 1 August 2005

L.J. Golonka, M. Buczek, M. Hrovat, D. Belavič, A. Dziedzic, H. Roguszczak and T. Zawada

To find properties of screen printed PZT (PbZr0.53Ti0.47O3 with 6 per cent of PbO and 2 per cent of Pb5Ge3O11) thick films layers on LTCC substrate.

Abstract

Purpose

To find properties of screen printed PZT (PbZr0.53Ti0.47O3 with 6 per cent of PbO and 2 per cent of Pb5Ge3O11) thick films layers on LTCC substrate.

Design/methodology/approach

The influence of PZT firing time and electrode materials on electrical characteristics and microstructure were examined. A scanning electron microscope (SEM) equipped with an energy‐dispersive X‐ray (EDS) analyser was used for the microstructural and compositional analysis.

Findings

Microstructural and compositional analyses have shown the diffusion of SiO2 from LTCC into PZT layers and the diffusion of PbO in the opposite direction. SiO2 presumably forms low permitivity lead based silicates in PZT layer. The new phase deteriorates the piezoelectric properties. The amount of diffused materials was dependent upon the electrode material and increased with increasing firing time. Better properties, i.e. higher remanent polarisation and dielectric constant were achieved for samples with PdAg electrodes and shorter firing time.

Originality/value

New information on electrical and microstructural properties of thick film PZT made on LTCC substrate.

Details

Microelectronics International, vol. 22 no. 2
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 7 August 2017

Darko Belavič, Andraž Bradeško, Tomaz Kos and Tadej Rojac

In this contribution, the design and integration of a piezoelectric vibrating device into low-temperature, co-fired ceramic (LTCC) structures are presented and discussed…

Abstract

Purpose

In this contribution, the design and integration of a piezoelectric vibrating device into low-temperature, co-fired ceramic (LTCC) structures are presented and discussed. The mechanical vibration of the diaphragm was stimulated with a piezoelectric actuator, which was integrated onto the diaphragm. Three different methods for the integration were designed, fabricated and evaluated.

Design/methodology/approach

The vibrating devices were designed as an edge-clamped diaphragm with an integrated piezoelectric actuator at its centre, whose role is to stimulate the vibration of the diaphragm via the converse piezoelectric effect. The design and feasibility study of the vibrating devices was supported by analytical methods and finite-element analyses.

Findings

The benchmarking of the ceramic vibrating devices showed that the thick-film piezoelectric actuator responds weakly in comparison with both the bulk actuators. On the other hand, the thick-film actuator has the lowest dissipation factor and it generates the largest displacement of the diaphragm with the lowest driving voltage. The resonance frequency of the vibrating device with the thick-film actuator is the most sensitive for an applied load (i.e. mass or pressure).

Research limitations/implications

Research activity includes the design and the fabrication of a piezoelectric vibrating device in the LTCC structure. The research work on the piezoelectric properties of integrated piezoelectric actuators was limited.

Practical implications

Piezoelectric vibrating devices were used as pressure sensors.

Originality/value

Piezoelectric vibrating devices could be used not only for pressure sensors but also for other type of sensors and detectors and for microbalances.

Details

Microelectronics International, vol. 34 no. 3
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 2 July 2018

Darko Belavic, Andraž Bradeško and Hana Uršič

The purpose of this study is to design, fabricate and investigate low-temperature co-fired ceramic (LTCC) structures with integrated microfluidic elements. Special…

Abstract

Purpose

The purpose of this study is to design, fabricate and investigate low-temperature co-fired ceramic (LTCC) structures with integrated microfluidic elements. Special attention is paid to the study of fluid properties of micro-channels and microvalves, which are important constitutive parts of both, microfluidic systems and individual microfluidic devices.

Design/methodology/approach

Several test patterns of fluid channels with different geometry and different types of valves were designed and realized in LTCC technology. All test structures were tested under the flow of two fluids (liquids): water and isopropyl alcohol. Flow rates at different applied pressure were measured and hydrodynamic resistance and diode effect were calculated.

Findings

The investigation of the channels showed that viscosity of fluidic media has significant influence on the hydrodynamic resistance in channels with rectangular cross-section, while this effect is small on channels with square cross-section. The viscosity also has a decisive influence on the diode effect of different shape of valves, and therefore, it is important in the selection of the valve in practical applications.

Research limitations/implications

In this work, the investigation of hydrodynamic resistance of channels and diode effect of passive valves is limited on selected geometry and only on two fluidic media and two applied pressures. All these and some other parameters have a significant influence on fluidic properties, but this will be the topic of the next research work, which will be supported by numerical modelling.

Practical implications

The presented results are useful in the future designing process of LTCC-based microfluidic devices and systems.

Originality/value

Microfluidic in the LTCC structures is an unconventional use of this technology. Therefore, the fluid properties are relatively unsearched. On the other hand, the global use of microfluidic devices and systems is growing rapidly in various applications. They are mostly made by polymer materials, however, in more demanding applications; ceramic is a useful alternative.

Details

Microelectronics International, vol. 35 no. 3
Type: Research Article
ISSN: 1356-5362

Keywords

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Article
Publication date: 1 December 2002

Marko Pavlin, Darko Belavic, Marina Santo Zarnik, Marko Hrovat and Matej Mozek

Pressure‐sensor miniaturization requires high‐density packaging. This means that designers are constantly faced with all kinds of challenging, and sometimes impossible…

Abstract

Pressure‐sensor miniaturization requires high‐density packaging. This means that designers are constantly faced with all kinds of challenging, and sometimes impossible, requirements. In this paper we will present three examples with specific technologies and aspects of miniaturization and packaging. The first example is a pressure switch, the second a pressure sensor and the third a smart pressure sensor.

Details

Microelectronics International, vol. 19 no. 3
Type: Research Article
ISSN: 1356-5362

Keywords

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Article
Publication date: 18 April 2008

Marina Santo Zarnik, Darko Belavic and Srecko Macek

The successful use of piezoceramic thick films in sensors and actuators requires a thorough understanding of their electrical and electromechanical characteristics. Since…

Abstract

Purpose

The successful use of piezoceramic thick films in sensors and actuators requires a thorough understanding of their electrical and electromechanical characteristics. Since these characteristics depend not only on the material's composition but also on its compatibility with various substrates and a number of processing parameters, accurate measurements of the material's parameters are essential. Here, the aim of this paper is to present a procedure for characterising lead‐zirconate‐titanate (PZT) thick films on pre‐fired low‐temperature co‐fired ceramic (LTCC) substrates performed in order to determine the material parameters for numerical modelling.

Design/methodology/approach

Owing to the lack of standard procedures for measuring the elastic and piezoelectric properties of the films, the compliance parameters were evaluated from the results of nano‐indentation tests, and a substrate‐flexure method was used to evaluate the transverse piezoelectric coefficients.

Findings

The validation of the material model and the finite‐element (FE) analysis of the demonstrator sensor/actuator structures are shown to be in agreement with the FE model, even if not an exact fit.

Originality/value

This paper focuses on a characterisation of PZT thick films screen‐printed on pre‐fired LTCC substrates.

Details

Microelectronics International, vol. 25 no. 2
Type: Research Article
ISSN: 1356-5362

Keywords

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Article
Publication date: 12 January 2021

Kostja Makarovič, Darko Belavič, Barbara Malič, Andreja Benčan, Franci Kovač and Janez Holc

The purpose of this study is the design, fabrication and evaluation of a miniature ozone generator using the principle of electric discharge are presented.

Abstract

Purpose

The purpose of this study is the design, fabrication and evaluation of a miniature ozone generator using the principle of electric discharge are presented.

Design/methodology/approach

The device was fabricated using a low-temperature co-fired ceramics (LTCC) technology, by which a multilayered ceramic structure with integrated electrodes, buried channels and cavities in micro and millimeter scales was realized.

Findings

The developed ozone generator with the dimensions of 63.6 × 41.8 × 1.3 mm produces approximately 1 vol. % of ozone in oxygen flow of 15 ml/min, at an applied voltage of 7 kV.

Originality/value

A miniature ozone generator, manufactured in LTCC technology, produces high amount of ozone and more than it is described in the available references or in datasheets of commercial devices of similar size.

Details

Microelectronics International, vol. 38 no. 1
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 2 August 2011

Marina Santo Zarnik, Darko Belavič and Srečko Maček

The purpose of this paper is to consider a capacitive pressure sensor fabricated using low‐temperature cofired ceramic (LTCC) materials and technology as a candidate for…

Abstract

Purpose

The purpose of this paper is to consider a capacitive pressure sensor fabricated using low‐temperature cofired ceramic (LTCC) materials and technology as a candidate for an energy‐autonomous sensor application. Designing the 3D capacitive sensor structure, with the cofired thick‐film electrodes inside the narrow air gap in the LTCC substrate, was a challenging task, particularly due to the presence of the parasitic elements influencing the sensor's characteristics.

Design/methodology/approach

In this work, different design variants for the thick‐film electrodes of the capacitive sensing structure were studied and compared. The test sensors were designed for the pressure range 0‐10 kPa and manufactured with readout electronics based on a capacitance‐to‐digital conversion.

Findings

The typical sensitivity obtained was 4 fF/kPa, and the temperature coefficient of the sensitivity was 0.03%/°C. The design variant with the guard‐ring electrode showed the best rms resolution of 50 Pa. One drawback of the application could be the sensitivity to atmospheric humidity and the influence of the different media.

Originality/value

This paper focuses on the design of a capacitive gas‐pressure sensor in a 3D LTCC structure. The present study provides a good basis for further optimisation of the design of the cofired electrodes in the capacitive sensing structure.

Details

Microelectronics International, vol. 28 no. 3
Type: Research Article
ISSN: 1356-5362

Keywords

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Article
Publication date: 3 August 2015

Darko Belavič, Marko Hrovat , Kostja Makarovič , Gregor Dolanč, Andrej Pohar , Stanko Hočevar and Barbara Malič

– The purpose of this paper is to present the research activity and results to research and development society on the field of ceramic microsystems.

Abstract

Purpose

The purpose of this paper is to present the research activity and results to research and development society on the field of ceramic microsystems.

Design/methodology/approach

The chemical reactor was developed as a non-conventional application of low temperature co-fired ceramic (LTCC) and thick-film technologies. In the ceramic reactor with a large-volume, buried cavity, filled with a catalyst, the reaction between water and methanol produces hydrogen and carbon dioxide (together with traces of carbon monoxide). The LTCC ceramic three-dimensional (3D) structure consists of a reaction chamber, two inlet channels, an inlet mixing channel, an inlet distributor, an outlet collector and an outlet channel. The inlet and outlet fluidic barriers for the catalyst of the reaction chamber are made with two “grid lines”.

Findings

A 3D ceramic structure made by LTCC technology was successfully designed and developed for chemical reactor – methanol decomposition.

Research limitations/implications

Research activity includes the design and the capability of materials and technology (LTCC) to fabricate chemical reactor with large cavity. But further dimensions-scale-up is limited.

Practical implications

The technology for the fabrication of LTCC-based chemical reactor was developed and implemented in system for methanol decomposition.

Originality/value

The approach (large-volume cavity in ceramic structure), which has been developed, can be used for other type of reactors also.

Details

Microelectronics International, vol. 32 no. 3
Type: Research Article
ISSN: 1356-5362

Keywords

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Article
Publication date: 1 March 1992

M. Pavšek, D. Belavič, U. Kunaver and M. Hrovat

The design of temperature‐compensated quartz crystal oscillators (TCXOs) in thick film hybrid technology is described. TCXOs controlled by varicap diodes are usually…

Abstract

The design of temperature‐compensated quartz crystal oscillators (TCXOs) in thick film hybrid technology is described. TCXOs controlled by varicap diodes are usually realised with discrete NTC thermistors and resistors. Data obtained by precision measurements of voltages on varicap diodes for the same oscillator frequencies over the operating temperature range are used for calculating values of the NTC thermistors and resistors. In most cases these values cannot be found in the Renard scale, with the result that manipulation or ‘juggling’ of values is necessary. The realisation of temperature‐compensating circuits in thick film technology has certain advantages, such as miniaturisation, better characteristics at high frequencies and in particular the possibility to trim thick film resistors and NTC thermistors to values calculated for each oscillator. The method of realisation of TCXOs in thick film hybrid technology was developed and verified on prototypes. The compensation curves were obtained by measuring compensation voltages for each oscillator over the operating temperature range from — 20°C to 70°C. From these data the values of resistors and NTC thermistors were calculated. A computer program was used to minimise frequency instability error as a function of six parameters (resistance). The frequency stability (Δf/f) of TCXOs obtained was better than ±2 ppm.

Details

Microelectronics International, vol. 9 no. 3
Type: Research Article
ISSN: 1356-5362

1 – 10 of 34