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1 – 10 of over 14000Andrzej Dziedzic, Pawel Osypiuk and Wojciech Steplewski
The paper aims to verify the influence of mechanical factors (longitudinal elongation at constant stretching velocity, constant elongation strain and cyclic compressive and…
Abstract
Purpose
The paper aims to verify the influence of mechanical factors (longitudinal elongation at constant stretching velocity, constant elongation strain and cyclic compressive and tensile stresses) on the electrical properties of thin-film and polymer thick-film resistors on flexible substrates.
Design/methodology/approach
Kapton foil was used as a substrate for all test samples. Designed resistive structures were made with the aid of two polymer thick-film resistive inks or OhmegaPly Ni-P resistive foil. Two different topologies – the horseshoe and triangular – were used. These topologies should have the opposite stability parameters.
Findings
Almost all presented data confirm the influence of the topology of resistors on stability of their electrical properties. The resistive materials applied for test structures also affect the stability under various mechanical exposures.
Originality/value
In general, the largest changes were caused by longitudinal elongation at constant stretching velocity, whereas other tests caused smaller changes of electrical properties. The measurements confirm the influence of topology on stability of electric properties.
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Flavio Allella, Elio Chiodo and Davide Lauria
Series capacitive compensation in electrical power systems is generally recognized as a very economical and powerful means for increasing the transmission capability of…
Abstract
Series capacitive compensation in electrical power systems is generally recognized as a very economical and powerful means for increasing the transmission capability of long‐distance transmission lines, resulting in relevant technical advantages in power system behavior: increased steady‐state and transient stability margins, reduced voltage drop in receiving systems during occurrence of severe contingencies and reduction of transmission losses. In this paper, a general method for choosing the series compensation degree is proposed, focusing the attention on the transient stability aspect. The approach, based upon a probabilistic framework, allows to properly select – at the design stage – the optimal degree of series compensation in order to contain the instability risk at an acceptable value. The transient stability problem is formulated by using the transient energy function method. In order to show the feasibility of the proposed approach, a numerical application to the Cigre test network is performed in the final part of the paper.
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G. van Alst, P. van Dijk and F. van Meijl
Various methods are described of makingseparable electrical connections to MID structures. The firstpart discusses the use of a copper plated,glass filled plastic substrate as a…
Abstract
Various methods are described of making separable electrical connections to MID structures. The first part discusses the use of a copper plated, glass filled plastic substrate as a contact surface. It is shown that the morphology is different from that of conventional contacts due to the presence of dendritic growths, further that mechanical properties like stiffness and strength are lower than for solid copper. The second part discusses the application of two conventional techniques ‐ elastromeric connectors and compliant pins. Elastomeric connectors are designed to form a high density, separable interface using gold plated conductors. Compliant pins pressed into plated‐through holes form very reliable, high normal force connections without the need for noble metal plating. Two compliant pin designs have been tested with plated holes in two versions, moulded and drilled. All combinations show excellent electrical stability; however, differences were found in mechanical behaviour between the various pin and hole combinations.
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Abstract
This paper reviews technologies used for the prevention of electromagnetic interference in current portable electronic products. It studies the need for future advanced products and some of the technologies likely to be available. The focus is on housing technologies and the products available for giving greatest electromagnetic compatibility with the latest European and other emission and susceptibility standards. It is concluded that new or improved approaches which are better able to ensure long‐term reliability will be essential for the 100 MHz clock speed equipment likely to be in production within the coming five years.
Ben Sitler and Ken Lo
Considers the causes of corrosion of avionics antennae and the damage damage it causes. Gives the authors’ view of the disadvantages of conventional antenna attachment and sealing…
Abstract
Considers the causes of corrosion of avionics antennae and the damage damage it causes. Gives the authors’ view of the disadvantages of conventional antenna attachment and sealing techniques. Details an alternative technique ‐ conductive gel gaskets ‐ using a gel sealant developed by Raychem Corporation.
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Jiayuan Yan, Xiaoliang Zhang and Yanming Wang
As a high-performance engineering plastic, polyimide (PI) is widely used in the aerospace, electronics and automotive industries. This paper aims to review the latest progress in…
Abstract
Purpose
As a high-performance engineering plastic, polyimide (PI) is widely used in the aerospace, electronics and automotive industries. This paper aims to review the latest progress in the tribological properties of PI-based composites, especially the effects of nanofiller selection, composite structure design and material modification on the tribological and mechanical properties of PI-matrix composites.
Design/methodology/approach
The preparation technology of PI and its composites is introduced and the effects of carbon nanotubes (CNTs), carbon fibers (CFs), graphene and its derivatives on the mechanical and tribological properties of PI-based composites are discussed. The effects of different nanofillers on tensile strength, tensile modulus, coefficient of friction and wear rate of PI-based composites are compared.
Findings
CNTs can serve as the strengthening and lubricating phase of PI, whereas CFs can significantly enhance the mechanical properties of the matrix. Two-dimensional graphene and its derivatives have a high modulus of elasticity and self-lubricating properties, making them ideal nanofillers to improve the lubrication performance of PI. In addition, copolymerization can improve the fracture toughness and impact resistance of PI, thereby enhancing its mechanical properties.
Originality/value
The mechanical and tribological properties of PI matrix composites vary depending on the nanofiller. Compared with nanofibers and nanoparticles, layered reinforcements can better improve the friction properties of PI composites. The synergistic effect of different composite fillers will become an important research system in the field of tribology in the future.
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Peter Lukacs, Alena Pietrikova and Pavol Cabuk
The purpose of this paper is to find optimal sintering conditions of silver-based nano-inks for achieving the high electrical conductivity of the deposited layers applied on…
Abstract
Purpose
The purpose of this paper is to find optimal sintering conditions of silver-based nano-inks for achieving the high electrical conductivity of the deposited layers applied on polyimide foils as well as the influence of ageing on the electrical conductivity. Therefore, the investigation in the field of silver layers deposited by inkjet printing technology is presented in this paper.
Design/methodology/approach
The four-point resistance measurements were realized for a detailed and precise analysis of the resistance of two different silver layers under different sintering conditions depending on the type of nano-ink varied about the recommended values. Highly accelerated stress tests (HASTs) were also applied as an ageing method for confirmation of the high electrical stability of the silver layers.
Findings
The results prove the strong influence of the temperature and the time of the sintering process on the sheet resistance of the investigated silver-based layers deposited by inkjet printing technology on polyimide foils. The HASTs caused significant changes in the electrical conductivity for both nano-inks presented in this paper. The existence of noticeable dependence among the resistivity, thermal treatment and ageing was proved.
Originality/value
The main benefit lays in the optimization of sintering conditions to improve the electrical conductivity of the silver layers. The paper also presents a new approach for a stability analysis of the silver layers by HASTs.
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On the one hand, this paper is to further understand the residents' differentiated power consumption behaviors and tap the residential family characteristics labels from the…
Abstract
Purpose
On the one hand, this paper is to further understand the residents' differentiated power consumption behaviors and tap the residential family characteristics labels from the perspective of electricity stability. On the other hand, this paper is to address the problem of lack of causal relationship in the existing research on the association analysis of residential electricity consumption behavior and basic information data.
Design/methodology/approach
First, the density-based spatial clustering of applications with noise method is used to extract the typical daily load curve of residents. Second, the degree of electricity consumption stability is described from three perspectives: daily minimum load rate, daily load rate and daily load fluctuation rate, and is evaluated comprehensively using the entropy weight method. Finally, residential customer labels are constructed from sociological characteristics, residential characteristics and energy use attitudes, and the enhanced FP-growth algorithm is employed to investigate any potential links between each factor and the stability of electricity consumption.
Findings
Compared with the original FP-growth algorithm, the improved algorithm can realize the excavation of rules containing specific attribute labels, which improves the excavation efficiency. In terms of factors influencing electricity stability, characteristics such as a large number of family members, being well employed, having children in the household and newer dwelling labels may all lead to poorer electricity stability, but residents' attitudes toward energy use and dwelling type are not significantly associated with electricity stability.
Originality/value
This paper aims to uncover household socioeconomic traits that influence the stability of home electricity use and to shed light on the intricate connections between them. Firstly, in this article, from the perspective of electricity stability, the characteristics of the power consumption of residents' users are refined. And the authors use the entropy weight method to comprehensively evaluate the stability of electricity usage. Secondly, the labels of residential users' household characteristics are screened and organized. Finally, the improved FP-growth algorithm is used to mine the residential household characteristic labels that are strongly associated with electricity consumption stability.
Highlights
The stability of electricity consumption is important to the stable operation of the grid.
An improved FP-growth algorithm is employed to explore the influencing factors.
The improved algorithm enables the mining of rules containing specific attribute labels.
Residents' attitudes toward energy use are largely unrelated to the stability of electricity use.
The stability of electricity consumption is important to the stable operation of the grid.
An improved FP-growth algorithm is employed to explore the influencing factors.
The improved algorithm enables the mining of rules containing specific attribute labels.
Residents' attitudes toward energy use are largely unrelated to the stability of electricity use.
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Andrzej Dziedzic, Edward Mis, Lars Rebenklau and Klaus‐Jurgen Wolter
This paper aims to present systematic studies of a wide spectrum of geometrical and electrical properties of thick‐film and LTCC microresistors (with designed dimensions between…
Abstract
Purpose
This paper aims to present systematic studies of a wide spectrum of geometrical and electrical properties of thick‐film and LTCC microresistors (with designed dimensions between 50 × 50 μm2 and 800 × 200 μm2).
Design/methodology/approach
The geometrical parameters (average length, width and thickness, relations between designed and real dimensions, distribution of planar dimensions) are correlated with basic electrical properties of resistors (sheet resistance and its distribution, hot temperature coefficient of resistance and its distribution distribution) as well as long term thermal stability and durability of microresistors to short electrical pulses.
Findings
Fodel process gives better resolution than standard screen‐printing and leads to smaller dimensions than designed, smaller absolute error and better uniformity of planar sizes. Microresistors made in full Fodel process show much weaker dimensional effect and exhibit noticeably smaller distribution of basic electrical properties.
Originality/value
Presents systematic studies of a wide spectrum of geometrical and electrical properties of thick‐film and LTCC microresistors.
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Environmental issues have an ever‐increasing influence on the selection of material and processes in electronic manufacturing. This paper discusses the use of conductive adhesives…
Abstract
Environmental issues have an ever‐increasing influence on the selection of material and processes in electronic manufacturing. This paper discusses the use of conductive adhesives as a replacement for solder on SMT printed circuit boards. As a result of a world‐wide market survey, a number of conductive adhesives have been selected. One of the two key issues of this paper has been to uncover the market for adhesive types and their composition. The other key issue has been the technical investigation of the influence of component termination and printed circuit surface types on adhesive bonding stability. Four different types of adhesives on two different metal surfaces are compared with conventional solder technology. Each adhesive has been applied to the PCBs by either screen printing or dispensing according to the manufacturer's recommendation, followed by curing. All PCBs went through thermal and humidity cycling followed by electrical measurements of resistance. Finally, all variants have been adhesion tested. All adhesive variants have been microsectioned for metallurgical and microstructure examination. Energy dispersive analysis of X‐ray (EDAX) of the metal particles in the adhesive has been carried out and documented. Rework of conductive joints is briefly commented on. Finally, aspects of occupational health are discussed concerning work with adhesive types. Work with epoxy based adhesives has been brouaht into special focus.