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Article
Publication date: 1 June 2000

Subhotosh Khan

Permittivity and dissipation factor (Dk and Df) are effects of polarization of different components of the dielectric substrate material when subjected to an electrical…

Abstract

Permittivity and dissipation factor (Dk and Df) are effects of polarization of different components of the dielectric substrate material when subjected to an electrical field. A database of these important design parameters for PWBs has been developed for Thermount RT. Effects of variations in the level of moisture (bone‐dry to completely saturated at various relative humidity levels), testing temperature (room temperature to 120uC) and testing frequencies (1MHz to 1.5GHz) on Dk and Df are reported. As the frequency of test is increased from 1MHz to 1.5GHz, the effect of moisture on the properties is reduced. Comparison with conventional glass/FR4 laminate properties shows the distinct advantage of Thermount. It is increasingly used in high frequency cellular telephone, satellite, and wireless applications which require HDI PWBs to achieve the highest packaging density at the lowest cost and weight.

Details

Circuit World, vol. 26 no. 2
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 6 August 2019

Yannapol Sriphutkiat and Yufeng Zhou

The capability of microparticle/objects patterning in the three-dimensional (3D) printing structure could improve its performance and functionalities. This paper aims to…

Abstract

Purpose

The capability of microparticle/objects patterning in the three-dimensional (3D) printing structure could improve its performance and functionalities. This paper aims to propose and evaluate a novel acoustic manipulation approach.

Design/methodology/approach

A novel method to accumulate the microparticles in the cylindrical tube during the 3D printing process is proposed by acoustically exciting the structural vibration of the cylindrical tube at a specific frequency, and subsequently, focusing the 50-μm polystyrene microparticles at the produced pressure node toward the center of the tube by the acoustic radiation force. To realize this solution, a piezoceramic plate was glued to the outside wall of a cylindrical glass tube with a tapered nozzle. The accumulation of microparticles in the tube and printing structure was monitored microscopically and the accumulation time and width were quantitatively evaluated. Furthermore, the application of such technology was also evaluated in the L929 and PC-12 cells suspended in the sodium alginate and gelatin methacryloyl.

Findings

The measured location of pressure and the excitation frequency of the cylindrical glass tube (172 kHz) agreed quite well with our numerical simulation (168 kHz). Acoustic excitation could effectively and consistently accumulate the microparticles. It is found that the accumulation time and width of microparticles in the tube increase with the concentration of sodium alginate and microparticles in the ink. As a result, the microparticles are concentrated mostly in the central part of the printing structure. In comparison to the conventional printing strategy, acoustic excitation could significantly reduce the width of accumulated microparticles in the printing structure (p < 0.05). In addition, the possibility of high harmonics (385 and 657 kHz) was also explored. L929 and PC-12 cells suspended in the hydrogel can also be accumulated successfully.

Originality/value

This paper proves that the proposed acoustic approach is able to increase the accuracy of printing capability at a low cost, easy configuration and low power output.

Details

Rapid Prototyping Journal, vol. 25 no. 5
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 3 November 2021

Ching-Hsiang Chen, Chien-Yi Huang and Yan-Ci Huang

The purpose of this study is to use the Taguchi Method for parametric design in the early stages of product development. electromagnetic compatibility (EMC) issues can be…

Abstract

Purpose

The purpose of this study is to use the Taguchi Method for parametric design in the early stages of product development. electromagnetic compatibility (EMC) issues can be considered in the early stages of product design to reduce counter-measure components, product cost and labor consumption increases due to a number of design changes in the R&D cycle and to accelerate the R&D process.

Design/methodology/approach

The three EMC characteristics, including radiated emission, conducted emission and fast transient impulse immunity of power, are considered response values; control factors are determined with respect to the relevant parameters for printed circuit board and mechanical design of the product and peripheral devices used in conjunction with the product are considered as noise factors. The optimal parameter set is determined by using the principal component gray relational analysis in conjunction with both response surface methodology and artificial neural network.

Findings

Market specifications and cost of components are considered to propose an optimal parameter design set with the number of grounded screw holes being 14, the size of the shell heat dissipation holes being 3 mm and the arrangement angle of shell heat dissipation holes being 45 degrees, to dispose of 390 O filters on the noise source.

Originality/value

The optimal parameter set can improve EMC effectively to accommodate the design specifications required by customers and pass test regulations.

Article
Publication date: 1 April 2000

Anne Seppälä, Kimmo Saarinen and Eero Ristolainen

Small and low cost unencapsulated SMD plastic film capacitors were manufactured with different terminal metal compositions and dielectric materials. Capacitors made with a…

Abstract

Small and low cost unencapsulated SMD plastic film capacitors were manufactured with different terminal metal compositions and dielectric materials. Capacitors made with a polyethylene naphthalate film dielectric were produced using a winding method. The terminals were metallized using the flame spraying process. The terminals of the test capacitors consisted of three different metal layers. The base metal layer, which was aluminum, was coated with brass or copper. The top layer was a sprayed lead‐free, tin‐based solder to ensure the solderability of the terminals. The reliability of the unencapsulated test capacitors was evaluated using standard temperature cycling, humidity storage, and high temperature environmental tests. Solderability and resistance to soldering heat were tested by mounting the test capacitors using the reflow soldering technique. The electrical properties including capacitance, insulation resistance, and dissipation factors at 1kHz and 100kHz were verified.

Details

Soldering & Surface Mount Technology, vol. 12 no. 1
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 1 April 1981

Peter J. Neagle and Thomas D. Newton

In attempts to meet the need for low‐loss materials capable of attaining the dielectric properties that are required for rapidly developing microwave and high speed…

Abstract

In attempts to meet the need for low‐loss materials capable of attaining the dielectric properties that are required for rapidly developing microwave and high speed digital equipment, polysulphone in its various forms has been undergoing investigation. Microwave dielectric properties are examined with respect to temperature and frequency, and three types of polysulphone are studied in depth, with testing for dielectric constant and dissipation factor. The material's physical properties are listed prior to advisory comments on special processing requirements. Its feasibility in multilayer production is currently being researched.

Details

Circuit World, vol. 8 no. 1
Type: Research Article
ISSN: 0305-6120

Article
Publication date: 27 September 2011

J.N. Sharma, H. Singh and Y.D. Sharma

The purpose of this paper is to analyze the free vibrations in a stress free and thermally insulated (or isothermal), homogeneous, transversely isotropic, solid cylinder…

Abstract

Purpose

The purpose of this paper is to analyze the free vibrations in a stress free and thermally insulated (or isothermal), homogeneous, transversely isotropic, solid cylinder based on three‐dimensional coupled thermoelasticity, which is initially undeformed and kept at uniform temperature.

Design/methodology/approach

The displacement potential functions have been introduced in the equations of motion and heat conduction in order to decouple the purely shear and longitudinal motions. The system of governing partial differential equations is reduced to four second‐order coupled ordinary differential equations in radial coordinate by using the method of separation of variables. The matrix Frobenius method of extended power series is employed to obtain the solution of coupled ordinary differential equations along the radial coordinate. The convergence analysis of matrix Frobenius method has been successfully carried out.

Findings

The purely transverse mode is found to be independent of the rest of the motion and temperature change. The natural frequency, dissipation factor, inverse quality factor and frequency shift of vibrations in a stress free solid cylinder get significantly affected due to thermal variations and thermo‐mechanical coupling.

Originality/value

A new procedure is used and compared to other methods available in the literature.

Details

Multidiscipline Modeling in Materials and Structures, vol. 7 no. 3
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 14 August 2019

Siddhartha Biswas

The purpose of this paper is to deal with the three-dimensional analysis of free vibrations in a stress-free and rigidly fixed homogeneous transversely isotropic hollow…

Abstract

Purpose

The purpose of this paper is to deal with the three-dimensional analysis of free vibrations in a stress-free and rigidly fixed homogeneous transversely isotropic hollow cylinder in the context of three-phase-lag (TPL) model of hyperbolic thermoelasticity.

Design/methodology/approach

The matrix Frobenius method of extended power series is employed to obtain the solution of coupled ordinary differential equations along the radial coordinate.

Findings

The natural frequency, dissipation factor and inverse quality factor in the stress-free and rigidly fixed hollow cylinder get significantly affected due to thermal vibrations and thermo-mechanical coupling.

Originality/value

The modified Bessel functions and matrix Frobenius method have been directly used to study the vibration model of a homogeneous, transversely isotropic hollow cylinder in the context of TPL model based on three-dimensional thermoelasticity.

Details

Multidiscipline Modeling in Materials and Structures, vol. 15 no. 6
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 6 June 2016

Sameh E Ahmed, Hakan F. Öztop and Khaled Al-Salem

The purpose of this paper is to investigate the effects of magnetic field and viscous dissipation on mixed convection heat transfer, fluid flow and entropy generation in a…

Abstract

Purpose

The purpose of this paper is to investigate the effects of magnetic field and viscous dissipation on mixed convection heat transfer, fluid flow and entropy generation in a porous media filled square enclosure heated with corner isothermal heater.

Design/methodology/approach

Finite volume method has been used to solve governing equations. A code is developed by FORTRAN and entropy generation is calculated from the obtained results of velocities and temperature. Results are presented via streamlines, isotherms, local and mean Nusselt number for different values of Richardson number (0.001=Ri=100), Hartmann number (0.001=Ha=100), Darcy number (0.001=Da=0.1), length of heaters (0.25=hx=hy=0.75) and viscous dissipation factors (10−4=ε=10−6).

Findings

It is observed that entropy is generated mostly due to lid-driven wall and right side of the heater. Entropy generation decreases with increasing of Hartmann number and heat transfer increases with decreasing of viscous parameter.

Originality/value

The originality of this work is to application of magnetic field and viscous dissipation on entropy generation in a lid-driven cavity with corner heater. Here, both corner heater and the external forces are original parameters.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 26 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 20 July 2010

A. Caignot, P. Ladevèze, D. Néron and J.‐F. Durand

The purpose of this paper is to propose a virtual testing strategy in order to predict damping due to the joints which are present in the ARIANE 5 launcher.

Abstract

Purpose

The purpose of this paper is to propose a virtual testing strategy in order to predict damping due to the joints which are present in the ARIANE 5 launcher.

Design/methodology/approach

Since engineering finite element codes do not give satisfactory results, either because they are too slow or because they cannot calculate dissipation accurately, a new computational tool is introduced based on the LArge Time INcrement (LATIN) method in its multiscale version.

Findings

The capabilities of the new strategy are illustrated on one of the joints of ARIANE 5. The damping predicted virtually is compared to experimental results, and the approach appears promising.

Originality/value

The tool which has been developed gives access to calculations which were previously unaffordable with standard computational codes, which may improve the design process of launchers. The code is transferred into ASTRIUM‐ST, where it is being used to build a database of dissipations in the joints of the ARIANE 5 launcher.

Details

Engineering Computations, vol. 27 no. 5
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 11 March 2016

Gauri Shanker Seth, Rohit Sharma, Bidyasagar Kumbhakar and Ali J Chamkha

An investigation of hydromagnetic two dimensional boundary layer flow with heat transfer of a viscous, incompressible, electrically conducting, heat absorbing and…

Abstract

Purpose

An investigation of hydromagnetic two dimensional boundary layer flow with heat transfer of a viscous, incompressible, electrically conducting, heat absorbing and optically thick heat radiating fluid over a permeable exponentially stretching sheet considering the effects of viscous and Joule dissipations in the presence of velocity and thermal slip is carried out.

Design/methodology/approach

Using similarity transform, governing differential equations representing mathematical model of the problem are solved with the help of fourth-order Runge-Kutta method along with shooting technique. Numerical solutions of fluid velocity and fluid temperature are depicted graphically for various values of pertinent flow parameters whereas numerical values of wall velocity gradient and wall temperature gradient are displayed graphically for various values of pertinent flow parameters.

Findings

Numerical results obtained in this paper are compared with earlier published results and are found to be in excellent agreement. Magnetic field and suction tend to enhance the wall velocity gradient whereas dimensionless co-ordinate, injection and velocity slip factor have reverse effect on it. Suction and heat absorption tend to enhance wall temperature gradient whereas magnetic field, velocity slip factor, injection, thermal radiation, thermal slip factor and viscous dissipation have reverse effect on it.

Originality/value

The investigation of this problem may have bearing in several engineering processes such as extrusion of plastic sheet, annealing and tinning of copper wire, paper production, crystal growing and glass blowing, continuous casting of metals and spinning of fibers.

Details

Engineering Computations, vol. 33 no. 3
Type: Research Article
ISSN: 0264-4401

1 – 10 of over 3000