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Article
Publication date: 1 April 1991

M. Huschka

Continuously increasing requirements drive multilayer manufacturers to search for advanced manufacturing technologies and to evaluate new materials. This paper provides an…

Abstract

Continuously increasing requirements drive multilayer manufacturers to search for advanced manufacturing technologies and to evaluate new materials. This paper provides an insight into new multilayer bonding methods, improvements offered by laminators, and why to select high performance materials for special applications.

Details

Circuit World, vol. 18 no. 1
Type: Research Article
ISSN: 0305-6120

Article
Publication date: 1 March 1990

M. Huschka

The actual press cycle is of utmost importance for the manufacture of multilayer printed circuit boards. It is necessary for both the engineers and the operators to…

Abstract

The actual press cycle is of utmost importance for the manufacture of multilayer printed circuit boards. It is necessary for both the engineers and the operators to understand its factors of influence in order to gain the highest production yields. This paper describes the differences between single‐stage and two‐stage press cycle, cold start and hot start, and also the difference between bonding of multilayers in a hydraulic press vs. in a vacuum autoclave. Detailed insight is given into what is actually happening during the press cycle and how it can be influenced. Special recommendations for bonding of no‐flow prepregs and of multilayers with buried via‐holes or metal cores are given in a separate chapter.

Details

Circuit World, vol. 16 no. 4
Type: Research Article
ISSN: 0305-6120

Article
Publication date: 21 May 2020

Rupali Singh and Devendra Kumar Sharma

Quantum-dot cellular automata (QCA) is a promising technology, which seems to be the prospective substitute for complementary metal-oxide semiconductor (CMOS). It is a…

Abstract

Purpose

Quantum-dot cellular automata (QCA) is a promising technology, which seems to be the prospective substitute for complementary metal-oxide semiconductor (CMOS). It is a high speed, high density and low power paradigm producing efficient circuits. These days, most of the smart devices used for computing, make use of random access memory (RAM). To enhance the performance of a RAM cell, researchers are putting effort to minimize its area and access time. Multilayer structures in QCA framework are area efficient, fast and immune to the random interference. Unlike CMOS, QCA multilayer architectures can be designed using active components on different layers. Thus, using multilayer topology in the design of a RAM cell, which is not yet reported in the literature can improve the performance of RAM and hence, the computing device. This paper aims to present the modular design of RAM cell with multilayer structures in the QCA framework. The fundamental modules such as XOR gate, 2:1 multiplexer and D latch are proposed here using multilayer formations with the goal of designing a RAM cell with the provision of read, write, set and reset control.

Design/methodology/approach

All the modules used to design a RAM cell are designed using multilayer approach in QCA framework.

Findings

The proposed multilayer RAM cell is optimized and has shown an improvement of 20% in cell count, 30% in area, 25% in area latency product and 48.8% in cost function over the other efficient RAM designs with set/reset ability reported earlier. The proposed RAM cell is further analyzed for the fault tolerance and power dissipation.

Research limitations/implications

Due to the multilayer structure, the complexity of the circuit enhances which can be eliminated using simple architectures.

Originality/value

The performance metrics and results obtained establish that the multilayer approach can be implemented in the QCA circuit to produce area efficient and optimized sequential circuits such as a latch, flip flop and memory cells.

Details

Circuit World, vol. 47 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 7 August 2020

Yueling Lyu, Yangzhi Chen and Yulin Wan

Selective laser melting (SLM) is an important advanced additive manufacturing technology. The existing SLM printing technology cannot manufacture the mechanical parts that…

Abstract

Purpose

Selective laser melting (SLM) is an important advanced additive manufacturing technology. The existing SLM printing technology cannot manufacture the mechanical parts that fully meet the requirements of high precision and strength. This paper aims to explore a new post-processing method for SLM 316L specimen, namely, using of the TiN/TiAlN multilayer coating fabricated by multi-arc ion plating on the surface of SLM specimens, for improving the performance of SLM specimens. The other purpose of this paper is compared the performances of the TiAlN/TiN multilayer coating machined specimen and the TiN/TiAlN multilayer coating SLM specimen.

Design/methodology/approach

The TiN/TiAlN multilayer coating is fabricated by multi-arc ion plating on the surface of 316L specimens. The surface morphology and selected mechanical properties of TiN/TiAlN multilayer coating plating on the SLM substrate specimen and the machined substrate specimen were studied in this paper. The analyzed properties included surface topography, micro hardness, the adhesion, the thickness and the wear resistance of TiN/TiAlN multilayer coating plating on the SLM substrate specimen and the machined substrate specimen.

Findings

The electron microscope images reveal that surface morphology of TiN/TiAlN multilayer coating plating on the SLM specimens is relatively flat, and there are some micro-particles in different sizes and pin holes dispersed on them. After TiN/TiAlN multilayer coating, the performances of SLM samples, such as micro hardness, the thickness and the wear resistance, were significantly improved. The micro hardness of TiN/TiAlN multilayer coating machined specimen is higher than that of TiN/TiAlN multilayer coating SLM specimen. However, the adhesion of TiN/TiAlN multilayer coating machined specimen is less than that of TiN/TiAlN multilayer coating SLM specimen.

Originality/value

The study provides a new post-processing method for SLM 316L specimen to improve the performance of SLM specimens and to enable SLM specimens to be applied in the field of precision mechanical transmission.

Details

Rapid Prototyping Journal, vol. 26 no. 9
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 5 March 2018

Jungki Lee and Hogwan Jeong

The purpose of this paper is to calculate near field and far field scattering of SH waves by multiple multilayered anisotropic circular inclusions using parallel volume…

Abstract

Purpose

The purpose of this paper is to calculate near field and far field scattering of SH waves by multiple multilayered anisotropic circular inclusions using parallel volume integral equation method (PVIEM) quantitatively.

Design/methodology/approach

The PVIEM is applied for the analysis of elastic wave scattering problems in an unbounded solid containing multiple multilayered anisotropic circular inclusions. It should be noted that this numerical method does not require the use of the Green’s function for the inclusion – only the Green’s function for the unbounded isotropic matrix is needed. This method can also be applied to solve general elastodynamic problems involving inhomogeneous and/or anisotropic inclusions whose shape and number are arbitrary.

Findings

A detailed analysis of the SH wave scattering problem is presented for multiple multilayered orthotropic circular inclusions. Numerical results are presented for the displacement fields at the interfaces and the far field scattering patterns for square and hexagonal packing arrays of multilayered circular inclusions in a broad frequency range of practical interest.

Originality/value

To the best of the authors’ knowledge, the solution for scattering of SH waves by multiple multilayered anisotropic circular inclusions in an unbounded isotropic matrix is not currently available in the literature. However, in this paper, calculation of displacements on interfaces and far field scattering patterns of multiple multilayered anisotropic circular inclusions using PVIEM as a pioneer of numerical modeling enables us to investigate the effects of single/multiple scattering, fiber packing type, fiber volume fraction, single/multiple layer(s), the multilayer’s geometry, isotropy/anisotropy and softness/hardness.

Article
Publication date: 16 May 2008

K.H. Low and Yuqi Wang

To present a method to model woven fibre reinforced metal matrix composite for multilayer circuit boards.

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Abstract

Purpose

To present a method to model woven fibre reinforced metal matrix composite for multilayer circuit boards.

Design/methodology/approach

This paper presents a hybrid modelling method to model multilayer multimaterial composites with the combination of metallic and woven composite plies. Firstly, 3D unit cells of woven composite are idealized as orthotropic plies, while metallic layers are taken as isotropic plies. Secondly, the idealized composite plies and metallic plies are modelled into a 2D multilayer finite element (FE). Lastly, scalar damage parameters are used for damage modelling.

Findings

Based on this method, static and dynamic analysis of multilayer composite can be performed at both micro and board levels. Meanwhile, the hybrid model illustrates a good agreement with the experimental results and good computational efficiency required for FE simulation. Conceptually, this study is aimed to provide an efficient damage modelling techniques for laminate composites and flexible modelling methodology for further development of new composite material systems.

Research limitations/implications

Damaging testing and simulation is not involved, although damaging modelling method is presented.

Originality/value

This model has high flexibility and efficiency: the micro structure and properties of reinforced fibres, polymer matrix and metallic plies can be changed conveniently in 3D mechanics unit‐cell model; the 2D structure of geometry model provides a high‐computational efficiency in the numerical simulation. The presented work also provides the damage modelling methods, multi‐linear damage law and scalar damage parameters, to simulate damage behaviour after impact.

Details

Circuit World, vol. 34 no. 2
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 14 July 2022

Yongliang Wang, Jin Huang and Guocheng Wang

This study aims to analyse the deep resource mining that causes high in situ stress, and the disturbance of tunnelling and mining which may induce large stress…

Abstract

Purpose

This study aims to analyse the deep resource mining that causes high in situ stress, and the disturbance of tunnelling and mining which may induce large stress concentration, plastic deformation and rock strata compression deformation. The depth of deep resources, excavation rate and multilayered heterogeneity are critical factors of excavation disturbance in deep rock. However, at present, there are few engineering practices used in deep resource mining, and it is difficult to analyse the high in situ stress and dynamic three-dimensional (3D) excavation process in laboratory experiments. As a result, an understanding of the behaviours and mechanisms of the dynamic evolution of the stress field and plastic zone in deep tunnelling and mining surrounding rock is still lacking.

Design/methodology/approach

This study introduced a 3D engineering-scale finite element model and analysed the scheme involved the elastoplastic constitutive and element deletion techniques, while considering the influence of the deep rock mass of the roadway excavation, coal seam mining-induced stress, plastic zone in the process of mining disturbance of the in situ stress state, excavation rate and layered rock mass properties at the depths of 500 m, 1,500 m and 2,500 m of several typical coal seams, and the tunnelling and excavation rates of 0.5 m/step, 1 m/step and 2 m/step. An engineering-scale numerical model of the layered rock and soil body in an actual mining area were also established.

Findings

The simulation results of the surrounding rock stress field, dynamic evolution and maximum value change of the plastic zone, large deformation and settlement of the layered rock mass are obtained. The numerical results indicate that the process of mining can be accelerated with the increase in the tunnelling and excavation rate, but the vertical concentrated stress induced by the surrounding rock intensifies with the increase in the excavation rate, which becomes a crucial factor affecting the instability of the surrounding rock. The deep rock mass is in the high in situ stress state, and the stress and plastic strain maxima of the surrounding rock induced by the tunnelling and mining processes increase sharply with the excavation depth. In ultra-deep conditions (depth of 2,500 m), the maximum vertical stress is quickly reached by the conventional tunnelling and mining process. Compared with the deep homogeneous rock mass model, the multilayered heterogeneous rock mass produces higher mining-induced stress and plastic strain in each layer during the entire process of tunnelling and mining, and each layer presents a squeeze and dislocation deformation.

Originality/value

The results of this study can provide a valuable reference for the dynamic evolution of stress and plastic deformation in roadway tunnelling and coal seam mining to investigate the mechanisms of in situ stress at typical depths, excavation rates, stress concentrations, plastic deformations and compression behaviours of multilayered heterogeneity.

Details

Engineering Computations, vol. 39 no. 8
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 2 August 2022

Seema Rani and Mukesh Kumar

Community detection is a significant research field in the study of social networks and analysis because of its tremendous applicability in multiple domains such as…

Abstract

Purpose

Community detection is a significant research field in the study of social networks and analysis because of its tremendous applicability in multiple domains such as recommendation systems, link prediction and information diffusion. The majority of the present community detection methods considers either node information only or edge information only, but not both, which can result in loss of important information regarding network structures. In real-world social networks such as Facebook and Twitter, there are many heterogeneous aspects of the entities that connect them together such as different type of interactions occurring, which are difficult to study with the help of homogeneous network structures. The purpose of this study is to explore multilayer network design to capture these heterogeneous aspects by combining different modalities of interactions in single network.

Design/methodology/approach

In this work, multilayer network model is designed while taking into account node information as well as edge information. Existing community detection algorithms are applied on the designed multilayer network to find the densely connected nodes. Community scoring functions and partition comparison are used to further analyze the community structures. In addition to this, analytic hierarchical processing-technique for order preference by similarity to ideal solution (AHP-TOPSIS)-based framework is proposed for selection of an optimal community detection algorithm.

Findings

In the absence of reliable ground-truth communities, it becomes hard to perform evaluation of generated network communities. To overcome this problem, in this paper, various community scoring functions are computed and studied for different community detection methods.

Research limitations/implications

In this study, evaluation criteria are considered to be independent. The authors observed that the criteria used are having some interdependencies, which could not be captured by the AHP method. Therefore, in future, analytic network process may be explored to capture these interdependencies among the decision attributes.

Practical implications

Proposed ranking can be used to improve the search strategy of algorithms to decrease the search time of the best fitting one according to the case study. The suggested study ranks existing community detection algorithms to find the most appropriate one.

Social implications

Community detection is useful in many applications such as recommendation systems, health care, politics, economics, e-commerce, social media and communication network.

Originality/value

Ranking of the community detection algorithms is performed using community scoring functions as well as AHP-TOPSIS methods.

Details

International Journal of Web Information Systems, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1744-0084

Keywords

Article
Publication date: 1 February 1987

R. Menzel

For the drilling of polyimide multilayers with acrylic adhesives, more care must be taken than for epoxy glass material. Due to the different mechanical properties in the…

Abstract

For the drilling of polyimide multilayers with acrylic adhesives, more care must be taken than for epoxy glass material. Due to the different mechanical properties in the multilayer ‘sandwich’ of the polyimide and the acrylic adhesive layers, the drilling parameters require a higher level of control. To avoid defects in the hole, such as nail heading of the polyimide or an uncontrolled ‘rip‐out’ of the acrylic adhesive, the relation between the cutting speed of the drill and the feed needs to be adjusted for each drill diameter. The following guidelines are valid: Wider drill diameters require a lower rotational speed and a lower feed to avoid deformation of the polyimide in the hole. Smaller drill diameters need high rotational speeds and a higher feed to minimise smear. In general, the drilling performance of wider drills is better than that of smaller drills. In all cases, it was impossible to prevent smear of the acrylic adhesive in the multilayer holes. The only reliable method for removing acrylic smear is by plasma etching. The minimum etch‐back required for acrylic adhesive was found to be ≥6 µm, which would be equivalent to an etch‐back of only 2 µm of the polyimide film. To achieve the etch‐back rate, the time in the plasma chamber should be between 20 and 30 minutes at 90–110°C. After the etch‐back, a high pressure water rinse is needed to remove some residues in the hole prior to through‐plating.

Details

Circuit World, vol. 13 no. 3
Type: Research Article
ISSN: 0305-6120

Article
Publication date: 1 January 1990

T. Gilles, Q. Reynolds and J. Steinberg

The increasing complexity of hybrid circuits has led to a need for a reliable multilayer system. As well as reliability, the manufacturer will, of course, also attach…

Abstract

The increasing complexity of hybrid circuits has led to a need for a reliable multilayer system. As well as reliability, the manufacturer will, of course, also attach considerable importance to material and production costs. Until now, thick film multilayer applications have been limited by the inability of existing technology to reduce their susceptibility to galvanic effects occurring between individual conductive layers during fabrication. Now, however, this company has developed a multilayer dielectric which prevents metal migration. The system is supported by conductor and resistor systems.

Details

Microelectronics International, vol. 7 no. 1
Type: Research Article
ISSN: 1356-5362

1 – 10 of over 4000