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1 – 10 of over 2000
Article
Publication date: 7 August 2017

Alena Pietrikova, Tibor Rovensky, Juraj Durisin, Igor Vehec and Ondrej Kovac

The purpose of this paper is to analyse the influence of various firing profiles on microstructural and dielectric properties of low-temperature, co-fired ceramic (LTCC…

Abstract

Purpose

The purpose of this paper is to analyse the influence of various firing profiles on microstructural and dielectric properties of low-temperature, co-fired ceramic (LTCC) substrates in a GHz frequency range. According these analyses, sintering process can be controlled and modified to achieve better performance of devices fabricated from LTCC substrates.

Design/methodology/approach

Samples from LTCC substrates GreenTape 951 and GreenTape 9K7 were sintered by four firing profiles. Basic firing profile recommended by the manufacturer was modified by increasing the peak temperature or the dwell time at the peak temperature. The influence of firing profile on microstructural properties was analysed according to measurements by X-ray diffractometer (application of the Cu K-alpha radiation and the Bragg-Brentano method), and the influence on dielectric properties (dielectric constant and dielectric losses) was analysed according to measurements by split cylinder resonator method at 9.7 and 12.5 GHz.

Findings

Rising of the peak temperature or extension of dwell time at this temperature has influence on all analysed properties of LTCC substrates. Size of crystallites can be changed by modification of firing profile as well as microdeformation. In addition, dielectric properties can be changed too by modification of the firing profile. Correlation between microdeformation and dielectric losses was observed.

Originality/value

The novelty of this work lies in finding the mutual relationship between changes in microstructural (size of grains and microdeformation) and dielectric properties (dielectric constant and dielectric losses) caused by different firing profiles.

Details

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

Keywords

Article
Publication date: 20 October 2022

Zhentao Wang, Pai Peng, Sujuan Zhong, Yafang Cheng and Dong Xu

The purpose of this paper on the one hand is to reduce the sintering temperature, shorten the sintering time and improve the electrical properties of the sample through…

Abstract

Purpose

The purpose of this paper on the one hand is to reduce the sintering temperature, shorten the sintering time and improve the electrical properties of the sample through the two-step flash sintering method and on the other hand is to study the effect of electric field on the phase structure, microstructure and electrical properties of the flash sintering sample.

Design/methodology/approach

In this paper, (Mg1/3Ta2/3)0.01Ti0.99O2 giant dielectric ceramics were prepared by conventional sintering and two-step flash sintering, respectively. Further, the effect of electric field (600–750 V/cm) on the electrical properties of (Mg1/3Ta2/3)0.01Ti0.99O2 giant dielectric ceramics was studied.

Findings

The results show that compared with the conventional sintering, the sintering temperature of the two-step flash sintering can be reduced by 200°C and the sintering time can be shortened by 12 times. All sintered samples were single rutile TiO2 structure. Compared with conventional sintering, two-step flash sintering samples have finer grain size. The two-step flash sintered sample has similar dielectric properties to the conventional sintered sample. The dielectric constant of flash sintered samples decreases with the increase of electric field. When the electric field is 700 V/cm, the ceramic sample has the optimal dielectric properties, where the dielectric constant is approximately 5.5 × 103 and the dielectric loss is about 0.18 at 1 kHz. Impedance spectroscopy analysis shows that the excellent dielectric properties are attributed to the internal barrier layer capacitance model.

Originality/value

This paper not only provides a new method for the preparation of co-doped TiO2 giant dielectric ceramics but also has great potential in greatly improving efficiency and saving energy.

Details

Microelectronics International, vol. 39 no. 4
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 1 February 1994

K. Laursen, D. Hertling, N. Berry, S.A. Bidstrup, P. Kohl and G. Arroz

Multichip modules provide short chip‐to‐chip interconnects in order to take advantage of the high speeds available in integrated circuits. One multichip approach utilises…

Abstract

Multichip modules provide short chip‐to‐chip interconnects in order to take advantage of the high speeds available in integrated circuits. One multichip approach utilises layers of embedded microstrip. In order to achieve the highest possible speed, it is necessary to use metals and dielectrics which have low relative dielectric constants and low loss. Polymer and polyimide dielectric materials hold great promise in MCM applications; however, their high frequency characteristics are often not well known. Since thin film dielectric properties may differ from the bulk properties, it is important to be able to determine the dielectric properties using on‐wafer measurement techniques rather than more conventional techniques. This paper focuses on some of the techniques available and discusses the advantages and shortcomings of different techniques for measuring dielectric properties.

Details

Microelectronics International, vol. 11 no. 2
Type: Research Article
ISSN: 1356-5362

Article
Publication date: 1 August 2016

Tibor Rovensky, Alena Pietrikova, Igor Vehec and Martin Kmec

The purpose of this paper is to create multilayer substrate (composite) from various low temperature co-fired ceramic (LTCC) substrates by their mutual combinations and to…

Abstract

Purpose

The purpose of this paper is to create multilayer substrate (composite) from various low temperature co-fired ceramic (LTCC) substrates by their mutual combinations and to analyse influence of these multilayer substrates on dielectric properties in GHz frequency range.

Design/methodology/approach

GreenTape 951, GreenTape 9K7 and Murata LFC were used to create compound multilayer substrates that include three layers: middle layer is from Murata LFC, and both upper and bottom layers are either from GreenTape 951 or GreenTape 9K7. Shrinkage in all x-, y- and z-axes of all substrates including multilayer substrates were analysed, and influence of different shrinkage on dielectric properties was examined by microstrip ring resonators applied on all mentioned of substrates.

Findings

The middle layer of Murata LFC has significant influence on shrinkage value of composites which has a good repeatability and minimalizes problems with design of multilayer LTCC devices. Impact of middle layer from Murata LFC on dielectric constant is not significant, but on the other hand Q factor (loss tangent) of these composites is increased according to inhomogeneity between single LTCC layers, especially at frequency around 6 GHz.

Originality/value

The novelty of this work lies in creating multilayers systems from different types of LTCC substrates to find combination with the most suitable physical and dielectric properties for various purposes in GHz range applications.

Details

Microelectronics International, vol. 33 no. 3
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 2 February 2015

A.J. Sunija, S. Siva Ilango and K.P Vinod Kumar

This paper aims to focus on the evaluation of the electrical properties of bio-based polyurethane material derived from cashew nut husk tannin and also the effect of…

Abstract

Purpose

This paper aims to focus on the evaluation of the electrical properties of bio-based polyurethane material derived from cashew nut husk tannin and also the effect of temperature and frequency on the dielectric values and alternate current (AC) conductivity.

Design/methodology/approach

Bio-based polyurethane is prepared from cashew nut husk tannin as polyol, their dielectric constant and dielectric loss factor are measured using an inductance capacitance resistance (LCR) metre, and the AC conductivity is determined using dielectric constant and loss values.

Findings

The dielectric constant values are high, and the values decrease with an increase in frequency but increase with an increase in temperature. The AC conductivity values are low; hence, the material can be categorized as insulators or semi-conductors. Because the polyurethanes have a good dielectric value and are cost-effective, as they are derived from renewable biomaterial waste, they have promising applications for the future.

Research limitations/implications

The experiment is carried out up to the frequency of 200 KHz because of the limitation in the instrument. But for the institute of printed circuits (IPC) and other specifications, the values of dielectric loss and dielectric constant will be generally coated for 1 MHz.

Practical implications

The high dielectric constant and loss values show that the polyurethane can be opted for use as capacitors in electronic devices, and the values are comparable to the requirements of IPC4101A/24IPC; hence, they are suitable for the application as printed circuit board (PCB) laminate.

Social implications

The use of biomaterial waste in the production of polyurethane will bring down the dependence of polyurethane industry on fossil fuel reserve, reduce carbon dioxide foot print and reduce the cost of production.

Originality/value

The motivation of the work was its ecological aspect and also aims on the use of an alternative bio-based material in the PCB industry.

Details

Circuit World, vol. 41 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 8 February 2011

Thomas Apeldorn, F. Wolff‐Fabris and V. Altstädt

The purpose of this paper is to investigate and present the properties of a new substrate material based on thermoplastic polymers (so‐called LuVo Board) for…

Abstract

Purpose

The purpose of this paper is to investigate and present the properties of a new substrate material based on thermoplastic polymers (so‐called LuVo Board) for high‐frequency applications.

Design/methodology/approach

The thermal, mechanical and electrical properties of a new thermoplastic substrate are investigated and compared to conventional substrates for printed circuit board (PCB) applications.

Findings

The new LuVo Board exhibits similar properties to commercially available high‐performance substrates. The main advantage of the LuVo Board is a reduction of manufacturing costs in comparison to conventional substrates, as a highly automated manufacturing process can be employed. Moreover, the LuVo Board exhibits some further advantages: the material is inherently flame resistant and can be thermally shaped after the assembly process.

Originality/value

This paper presents an entirely new thermoplastic substrate, which can be employed in high‐frequency applications. In comparison to standard materials, a further advantage of the thermoplastic substrate is lower production costs.

Details

Circuit World, vol. 37 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 1 January 1987

W. Yext, E.A. Hayduk and C.K. Fisher

Manufacturers of multilayer copper thick‐film circuitry face the challenge of firing parts in an inert nitrogen atmosphere to prevent the copper from oxidising. Nitrogen…

Abstract

Manufacturers of multilayer copper thick‐film circuitry face the challenge of firing parts in an inert nitrogen atmosphere to prevent the copper from oxidising. Nitrogen, while protecting the copper from oxidation, offers no efficient mechanism for removing the carbon‐based vehicles used in the copper thick‐film paste. Because of this, carbon residues or soot often deposit on the parts during the firing process. In an attempt to improve the nitrogen furnace atmosphere's ability to remove the vehicles, several gases or gas blends were added to a nitrogen‐based furnace atmosphere. Thick‐film copper conductors and dielectric test pieces were then processed using the various gas blends. The physical properties of adhesion, aged adhesion, solderability, and conductivity of the copper conductor test pieces were studied along with the dielectric properties of dissipation factor, insulation resistance, and dielectric constant. Some of the gases tested included H2, H2O, CO, CO2, and a variety of other gas combinations. Test results demonstrated the atmosphere's ability to effect changes in the physical properties of the parts being processed. A proprietary gas blend was developed which proved effective in removing carbon residues while maintaining the desirable physical properties of the thick films. This work demonstrates the ability of certain gas additives to improve the performance of conventional nitrogen atmospheres when firing copper thick‐film circuitry. With the proper selection of the gas additive, atmosphere flows can be reduced, carbon residues eliminated, and the physical properties of the copper conductors and dielectrics maintained or improved.

Details

Microelectronics International, vol. 4 no. 1
Type: Research Article
ISSN: 1356-5362

Article
Publication date: 10 May 2021

Jiahao Shi, Ling Weng, Xiaoming Wang, Xue Sun, Shuqiang Du, Feng Gao and Xiaorui Zhang

Epoxy resin (EP) is a kind of thermosetting resin, and its application is usually limited by poor toughness. In this case, a type of new flexible chain blocking…

Abstract

Purpose

Epoxy resin (EP) is a kind of thermosetting resin, and its application is usually limited by poor toughness. In this case, a type of new flexible chain blocking hyperbranched polyester (HBP) was designed and synthesized. The purpose of this study is to enhance the toughness and dielectric properties of EP.

Design/methodology/approach

P-toluene sulfonic acid was used as the catalyst, with dimethy propionic acid as the branch unit and pentaerythritol as the core in the experiment. Then, n-hexanoic acid and n-caprylic acid were, respectively, put to gain HBP with a n-hexanoic acid and n-caprylic acid capped structure. The microstructure, mechanical properties, insulation properties and dielectric properties of the composite were characterized for the purpose of finding the appropriate proportion of HBP.

Findings

HBP enhanced the toughness of epoxy-cured products by interpenetrating polymer network structure between the flexible chain of HBP and the EP molecular chain. Meanwhile, HBP reduced the ε and tgδ of the epoxy anhydride-cured product by reducing the number of polar groups per unit volume of the EP through free volumes.

Research limitations/implications

Yet EP is a kind of thermosetting resin, which is widely used in coating, aerospace, electronics, polymer composites and military fields, but it is usually limited by poor toughness. In a word, it is an urgent priority to develop new EP with better toughness and mechanical properties.

Originality/value

At present, HBP has been applied as a new kind of toughening strategy and as a modifier for EP. According to the toughening mechanism of HBP modified EP, the free volume of HBP creates a space for the EP molecule to move around when loaded. Moreover, the free volume could cause the dielectric constant of EP to diminish by reducing the content of polarizable groups. Meanwhile, the addition of HBP with flexible chains grafted to the EP could develop an interpenetrating network structure, thus further enhancing the toughness of EP

Details

Pigment & Resin Technology, vol. 51 no. 1
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 1 February 1997

A‐A.M.A. Nada, E.A.M. Youssef and K.N. Abdel‐Nour

Presents findings from a study of the effects of treating unbleached bagasse paper sheets with different resin solutions. Unbleached kraft bagasse paper sheets were…

401

Abstract

Presents findings from a study of the effects of treating unbleached bagasse paper sheets with different resin solutions. Unbleached kraft bagasse paper sheets were treated with different resin solutions such as nitrocellulose, melamine formaldehyde, silicone, short and medium alkyd resin and the physico‐mechanical properties of the modified paper sheets were tested. The strength properties of treated paper sheets were highly improved especially in the case of treatment with melamine formaldehyde and silicone resin solutions. The effect of dipping time of paper sheets in different concentrations of resin solution on the strength properties was also investigated. Physico‐mechanical properties of thermally treated modified paper sheets with resins were also clarified. Concludes that promising results in the improvement of insulation of treated paper sheets with resin are obtained by studying the dielectric‐electric properties.

Details

Pigment & Resin Technology, vol. 26 no. 1
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 1 December 1997

P. Barnwell and J. Wood

Thick film technology has been widely used in the past for medium performance packagingsolutions, but has been unable to compete with thin‐film technology for…

161

Abstract

Thick film technology has been widely used in the past for medium performance packaging solutions, but has been unable to compete with thin‐film technology for high performance requirements. The problems of poor geometrical resolution, together with high dielectric constant and loss, have all contributed to the very limited adopting of thick‐film for advanced applications such as MCMs and microwave. This paper describes a new advanced ceramic based technology using thick‐film conductors and dielectric. Results showing the excellent geometrical properties which result from a combination of novel materials and processing, giving line widths down to 10 microns and via dimensions of 25 micron are presented. The novel dielectric material also provides a dielectric constant of 4, with a loss factor of 1 × 10−4. This technology allows the fabrication of high density circuits and packages, offering many packaging solutions, including MCM, microwave, sensors and displays, all on one substrate.

Details

Microelectronics International, vol. 14 no. 3
Type: Research Article
ISSN: 1356-5362

Keywords

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