Search results

1 – 10 of 16
Article
Publication date: 14 September 2011

Jacob Azoulay

The high Tc superconductors (HTS) are characterized by magneto electric anisotropy due to their pronounced material anisotropy. It is expected to observe also some…

Abstract

The high Tc superconductors (HTS) are characterized by magneto electric anisotropy due to their pronounced material anisotropy. It is expected to observe also some mechanical anisotropy. The mechanical properties of c-axis oriented and <110>-axis oriented films are reported. The two differently orientated films comprise an ideal case for comparative studies on mechanical anisotropy. Scanning electron microscope (SEM) and atomic force microscope (AFM) were used to study the films' surface. Nanoindentation and nanoscratch techniques were used to test the elastic behaviors and hardness of the films. Mechanical anisotropies was found, analyzed and discussed.

Details

World Journal of Engineering, vol. 8 no. 3
Type: Research Article
ISSN: 1708-5284

Keywords

Article
Publication date: 1 December 1998

Gábor Harsányi, Yanqing Liu and W. Kinzy Jones

Specially formulated frit materials have been applied in thick film superconductors similar to the standard thick film materials in order to achieve processing parameters…

220

Abstract

Specially formulated frit materials have been applied in thick film superconductors similar to the standard thick film materials in order to achieve processing parameters closely compatible with conventional thick film technology and alumina substrates. The applied frits have improved the adhesion and superconductor properties at the same time due to a superconductor bridge formation between the grains. Both YBCO and BSCCO systems have been analyzed. The results are promising.

Details

Microelectronics International, vol. 15 no. 3
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 1 February 2016

Attila Géczy, Bíborka Kvanduk, Balazs Illes and Gábor Harsányi

The paper aims to present a comparative study of various thermocouple (TC) attaching methods for the proper measurement of soldering temperature profiling during vapour…

Abstract

Purpose

The paper aims to present a comparative study of various thermocouple (TC) attaching methods for the proper measurement of soldering temperature profiling during vapour phase soldering (VPS). The heat transfer process during VPS is different from common methods, while the required heat for reflow is provided by the condensation. The condensate is a flowing layer on the board, where the dynamic behaviour also affects the local conditions on the surfaces. Temperature measurements based on TCs are also affected this way; it is important to investigate the process for deeper understanding.

Design/methodology/approach

Bare printed circuit boards (PCBs) were prepared for standard K-Type TCs attachment with industry standard materials: kapton polyimide tape, aluminium tape, SMD adhesive and high-temperature solder (HTS). Heating experiments were performed in a batch-type VPS oven with Galden LS240 fluid and fixed oven parameters.

Findings

According to the specific attachment requirements, HTS and Alu-tape are the suggested methods for better profiling reliability and repeatability. Alu-tape is the preferred all-around method, for fast, exchangeable, cheap, reliable and repeatable profiling in a VPS oven. It was presented that the heating factor (Q?) gives more reliable comparison overview; the time period-based comparisons may be affected by the thermal inertia, while heating factor also includes temperature conditions at the given time points.

Originality/value

The paper presents the reliability of the presented methods for VPS and present suggestions for the use of different TC ends and attaching materials during condensation heating of the PCBs. Also a new approach on profiling data evaluation based on the heating factor is presented and suggested for wider use.

Details

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

Keywords

Article
Publication date: 1 January 2014

Ouarda Barkat

An improved analytical model is presented to investigate the scattering properties of high Tc superconducting triangular antennas in multilayered configuration. The…

Abstract

Purpose

An improved analytical model is presented to investigate the scattering properties of high Tc superconducting triangular antennas in multilayered configuration. The spectral method is used to study the scattering properties of superconducting triangular antennas. Galerkin method is used in the resolution of the electric field integral equation. The boundary condition for the electric field was used to derive an integral equation for the electric current. To validate the theoretical results, a study has been performed for perfectly conducting triangular patch on a single layer, with air gap, and cover layer. The computed data are found to be in good agreement. The paper aims to discuss these issues.

Design/methodology/approach

A spectral domain approach has been used for the numerical calculation of the characteristics of a high Tc superconducting microstrip antenna with an air gap and cover layer. Initially, the authors use an integral method of moment which enabled them to exploit the spectral tensor of green. The resolution of the integral equations of the electric field by the procedure of Galerkin makes it possible to lead to a system of equations homogenous. The authors have calculated the frequency of resonance and the radiation pattern of antenna.

Findings

The properties of the HTSTMA structure were stable at temperatures slightly lower than the critical temperature. Also computations show that the air separation can be adjusted to have the maximum operating frequency of the superconducting microstrip antenna. On the other hand, the bandwidth increases monotonically with increasing the air gap width. Therefore, HTS materials do offer efficiency improvements for antenna systems that can accommodate the added constraints of the superconducting environment. The calculated results have been compared with measured one available in the literature and excellent agreement has been found.

Originality/value

To the best of the authors' knowledge, this subject has not been reported in the open literature; the only published results on the analysis of perfectly conducting triangular microstrip antennas.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 33 no. 1/2
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 January 1989

Electro‐Science Laboratories Inc., whose thick film pastes and materials for the microelectronics industry are manufactured and distributed in Europe by Agmet Ltd of…

Abstract

Electro‐Science Laboratories Inc., whose thick film pastes and materials for the microelectronics industry are manufactured and distributed in Europe by Agmet Ltd of Reading, have announced that Michael Alan Stein was elected President with effect from 16 September 1988. At the same time Dr Sidney J. Stein was elected Chairman of the Board of Directors.

Details

Microelectronics International, vol. 6 no. 1
Type: Research Article
ISSN: 1356-5362

Article
Publication date: 17 January 2019

Lubomir Livovsky and Alena Pietrikova

The purpose of this paper is to investigate measurement and regulation of saturated vapour height level in vapour phase soldering (VPS) chamber based on parallel plate…

Abstract

Purpose

The purpose of this paper is to investigate measurement and regulation of saturated vapour height level in vapour phase soldering (VPS) chamber based on parallel plate capacitor and retaining a stable saturated vapour level above the boiling fluid, regardless of the quantity and size of assembled components.

Design/methodology/approach

Development and realisation of capacitance sensor that sensitively senses the maximum height level of saturated vapour above the boiling fluid in the VPS chamber was achieved. Methodology of measurement is based on capacitor change from single air to a parallel plate, filled with two dielectric environments in a stacked configuration: condensed fluid and vapour (air).

Findings

An easy air plate capacitor immersed in the saturated vapour above the boiling fluid can serve as a parallel plate capacitor owing to the conversion of the air to the parallel plate capacitor. A thin film of fluid between the two capacitor plates corresponds to the height of the saturated vapour, which changes the capacity of the parallel plate capacitor.

Originality/value

Introducing the capacitive sensor directly into the VPS work space allows to achieve a constant height level of saturated vapour. Based on the capacity change, it is possible to control the heating power. There is a lack of information regarding measurement of stable height of vapour in the industry, and the present article shows how to easily improve the way to regulate the bandwidth of saturated vapour in the VPS process.

Details

Soldering & Surface Mount Technology, vol. 31 no. 3
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 1 December 2004

H. Ohsaki, Y. Ichiki and S. Sugita

A numerical analysis tool has been developed to study electromagnetic characteristics of high‐temperature superconducting thin film used for a resistive‐type fault current…

Abstract

A numerical analysis tool has been developed to study electromagnetic characteristics of high‐temperature superconducting thin film used for a resistive‐type fault current limiter (FCL) and coated conductor. It adopts the finite element method based on current vector potentials with thin‐plate approximation. Transport current, temperature dependence and strong non‐linearity of electromagnetic properties, and state transition of superconductor are taken into account by solving a three‐dimensional coupled problem of electromagnetic field, an electric circuit and thermal field. Then using this numerical analysis tool the current imbalance and current limiting characteristics of a FCL device, the influence of inhomogeneity of superconducting properties on them, and AC losses in YBCO coated conductor are studied.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 23 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 7 September 2015

Lilan Gao, Hong Gao and Xu Chen

This review paper aims to provide a better understanding of formulation and processing of anisotropic conductive adhesive film (ACF) material and to summarize the…

Abstract

Purpose

This review paper aims to provide a better understanding of formulation and processing of anisotropic conductive adhesive film (ACF) material and to summarize the significant research and development work for the mechanical properties of ACF material and joints, which helps to the development and application of ACF joints with better reliability in microelectronic packaging systems.

Design/methodology/approach

The ACF material was cured at high temperature of 190°C, and the cured ACF was tested by conducting the tensile experiments with uniaxial and cyclic loads. The ACF joint was obtained with process of pre-bonding and final bonding. The impact tests and shear tests of ACF joints were completed with different aging conditions such as high temperature, thermal cycling and hygrothermal aging.

Findings

The cured ACF exhibited unique time-, temperature- and loading rate-dependent behaviors and a strong memory of loading history. Prior stress cycling with higher mean stress or stress amplitude restrained the ratcheting strain in subsequent cycling with lower mean stress or stress amplitude. The impact strength and adhesive strength of ACF joints increased with increase of bonding temperature, but they decreased with increase of environment temperature. The adhesive strength and life of ACF joints decreased with hygrothermal aging, whereas increased firstly and then decreased with thermal cycling.

Originality/value

This study is to review the recent investigations on the mechanical properties of ACF material and joints in microelectronic packaging applications.

Details

Soldering & Surface Mount Technology, vol. 27 no. 4
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 8 August 2019

Loïc Burger, Christophe Geuzaine, Francois Henrotte and Benoît Vanderheyden

Finite element (FE) models are considered for the penetration of magnetic flux in type-II superconductor films. A shell transformation allows boundary conditions to be…

Abstract

Purpose

Finite element (FE) models are considered for the penetration of magnetic flux in type-II superconductor films. A shell transformation allows boundary conditions to be applied at infinity with no truncation approximation. This paper aims to determine the accuracy and efficiency of shell transformation techniques in such non-linear eddy current problems.

Design/methodology/approach

A three-dimensional H – ϕ formulation is considered, where the reaction field is calculated in the presence of a uniform applied field. The shell transformation is used in the far-field region, and the uniform applied field is introduced through surface terms, so as to avoid infinite energy terms. The resulting field distributions are compared against known solutions for different geometries (thin disks and thin strips in the critical state, square thin films). The influence of the shape, size and mesh quality of the far-field regions are discussed.

Findings

The formulation is shown to provide accurate results for a number of film geometries and shell transformation shapes. The size of the far-field region has to be chosen in such a way to properly capture the asymptotic decay of the fields, and a practical procedure to determine this size is provided.

Originality/value

The importance of the size of the far-field region in a shell transformation and its proximity to the conducting domains are both highlighted. This paper also provides a numerical way to apply a constant magnetic field in a given region, while the source, on which only the far-field behaviour of the applied field depends, is excluded from the model.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 38 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 8 May 2018

Daoyu Hu, Jianwen Zhang, Feng Gu and Zhuyong Li

The purpose of this study is to propose a modeling method of the equivalent circuit for a new type of high-temperature superconducting partial-core transformer (HTS-PCT…

Abstract

Purpose

The purpose of this study is to propose a modeling method of the equivalent circuit for a new type of high-temperature superconducting partial-core transformer (HTS-PCT) made of ReBCO-coated conductors.

Design/methodology/approach

The modeling process is based on the “Steinmetz” equivalent circuit. The impedance components in the circuit are obtained by the calculations of the core losses and AC losses of the HTS windings by using theoretical methods. An iterative computation is also used to decide the equivalent resistances of the AC losses of the primary and secondary HTS windings. The reactance components in the circuit are calculated from the energy stored in the magnetic fields by finite element method. The validation of the modeling method is verified by experimental results

Findings

The modeling method of the equivalent circuit of HTS-PCT is valid, and an equivalent circuit for HTS-PCT is presented.

Practical implications

The equivalent circuit of HTS-PCT could be obtained by the suggested modeling method. Then, it is easy to analyze the characteristics of the HTS-PCT by its equivalent circuit. Moreover, the modeling method could also be useful for the design of a specific HTS-PCT.

Originality/value

The study proposes a modeling method of the HTS-PCT made of the second-generation HTS tapes, i.e. ReBCO-coated conductors.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 37 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

1 – 10 of 16