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Article
Publication date: 1 September 2005

Dezhi Li, Changqing Liu and Paul P. Conway

To study the influence of storage time and environment on the solderability of electroless nickel plated samples with Sn‐3.8Ag‐0.7Cu and Sn‐3.5Ag lead‐free solders and to…

Abstract

Purpose

To study the influence of storage time and environment on the solderability of electroless nickel plated samples with Sn‐3.8Ag‐0.7Cu and Sn‐3.5Ag lead‐free solders and to provide criteria for the use of an electroless nickel (Ni‐P) under bump metallization (UBM) without immersion gold protection.

Design/methodology/approach

Electroless nickel coatings were deposited onto pure aluminium foil through a procedure developed for the UBM of wafers prior to flip chip bumping. Their solderability with lead‐free solders was studied using the wetting balance technique. Samples stored in different environments for different periods of time were tested to study the dependence of the solderability of Ni‐P coatings on the storage time and temperature. The degree of oxidation of the Ni‐P coatings was examined by means of X‐ray photoelectron spectroscopy and the surface microstructure and roughness of the coatings were analyzed by scanning electron microscopy and atomic force microscopy.

Findings

It was found that the Ni‐P coatings were unacceptable for direct soldering without the assistance of a flux, due to poor wettability, even when using a freshly prepared Ni‐P coating. Therefore, a suitable flux with nitrogen inerting had to be applied to assist the soldering process. The results also show that the solderability of Ni‐P coatings was affected by the phosphorus content, and the Ni‐P coating with high phosphorus content had a good solderability. The storage time and temperature did not influence the wettability significantly with the assistance of strong flux.

Research limitations/implications

The stability of the plating solution and the consistence of the phosphorus content in the coating are not easily controlled. This has resulted in implications for surface analysis and wetting testing. Ni‐P coatings with different levels of phosphorus content are being investigated in detail.

Originality/value

The value of the paper lies in its study on the solderability of lead‐free solders to Ni‐P coating after storage in different environments and for different periods, which can provide some criteria for the use of Ni‐P UBM without immersion gold protection.

Details

Circuit World, vol. 31 no. 3
Type: Research Article
ISSN: 0305-6120

Keywords

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Article
Publication date: 11 May 2012

Shefiu S. Zakariyah, Paul P. Conway, David A. Hutt, Navin Suyal and David R. Selviah

The purpose of this paper is to present the need, and a potential solution, for in‐plane routing of optical signals for optical‐enabled circuit boards.

Abstract

Purpose

The purpose of this paper is to present the need, and a potential solution, for in‐plane routing of optical signals for optical‐enabled circuit boards.

Design/methodology/approach

Multimode waveguides and integrated 45° in‐plane mirror structures were made in a low loss acrylate‐based photopolymer using excimer laser ablation. The fabrication of multimode waveguides and mirrors was carried out in a single laser system which minimised alignment issues.

Findings

It was established that in‐plane mirror fabrication using laser ablation can be achieved and can potentially be used to define mirrors in waveguides made by other methods such as photolithography.

Research limitations/implications

While the concept (integrated in‐plane mirror) was demonstrated, the viability of its deployment will depend on the results of optical loss measurements for which further research is required.

Originality/value

The paper gives an overview of the design concept and fabrication steps for an in‐plane embedded mirror.

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Article
Publication date: 13 February 2007

David A. Hutt, Karen Williams, Paul P. Conway, Fuad M. Khoshnaw, Xiaoyun Cui and Deepa Bhatt

To present the aims and preliminary findings of a research project to investigate the manufacture of multilayer glass substrates built up from thin glass sheets.

Abstract

Purpose

To present the aims and preliminary findings of a research project to investigate the manufacture of multilayer glass substrates built up from thin glass sheets.

Design/methodology/approach

The approaches that may be taken to create glass substrates and the challenges involved are described. Excimer laser machining was used for the formation of microvias and other features in individual glass sheets. In addition, methods for the electroless copper metallisation of the smooth glass surfaces were studied. Finally, a technique for the lamination of the glass layers using low temperature, pressure assisted bonding was investigated.

Findings

Microvias with 100 μm diameter entry holes were successfully machined in 100 μm thick glass sheets and process windows were identified to reduce debris and hole taper. Using appropriate pre‐treatment steps, electroless copper coatings could be deposited uniformly over the smooth glass surface, however, further improvements in adhesion were found to be necessary. The direct lamination of glass layers was found to be possible using pressure and temperature applied over long periods of time. Improvements to the lamination process were made to reduce the initiation of cracks which were assessed using fatigue testing.

Research limitations/implications

The feasibility of the individual steps in the fabrication of glass substrates has been demonstrated. Further work is necessary to control the processes in order to limit microcrack formation, improve copper coating adhesion and ensure uniform lamination of multiple glass layers.

Originality/value

The use of glass materials could enable the manufacture of substrates for high density electrical interconnect with integrated optical waveguides.

Details

Circuit World, vol. 33 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

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Article
Publication date: 3 February 2012

Olivia M. Flaherty, Xiaoyun Cui, Divya Rajamohan, David Hutt, Chris Denning, Paul P. Conway and Andrew A. West

The purpose of this paper is to highlight a novel manufacturing process for a biochip with a multi‐electrode array (MEA) that is specifically designed for use in…

Abstract

Purpose

The purpose of this paper is to highlight a novel manufacturing process for a biochip with a multi‐electrode array (MEA) that is specifically designed for use in characterising cardio‐active substances and to demonstrate a novel proposed solution prototype that has been constructed to meet the needs of end‐users.

Design/methodology/approach

Practical problems encountered with conventional MEA biochips are described and a novel biochip design to tackle these problems is presented. The manufacturing approach used to produce the prototypes of that design is described and depicted.

Findings

The novel prototype MEA biochips were successfully manufactured using conventional electronics manufacturing approaches. Prototypes demonstrated limited successes in the early stages of testing. Further revisions of the feature geometry are required to implement an alternative MEA biochip that is suitably reliable.

Research limitations/implications

Basic photolithography techniques have been used to construct a base substrate for proof‐of‐principle studies. Increased sophistication in manufacturing stages is required in future iterations of the proposed concept.

Originality/value

This paper introduces a problem encountered by MEA system adopters that requires a suitable solution. The scale up of an electronics manufacturing process‐based solution to the problems described holds much promise for the screening of new chemical entities.

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Article
Publication date: 16 May 2008

David R. Selviah, F. Aníbal Fernández, Ioannis Papakonstantinou, Kai Wang, Hadi Bagshiahi, Andy C. Walker, Aongus McCarthy, Himanshu Suyal, David A. Hutt, Paul P. Conway, John Chappell, Shefiu S. Zakariyah and Dave Milward

To introduce the Innovative Electronics Manufacturing Research Centre Flagship Project: Integrated Optical and Electronic Interconnect PCB Manufacturing, its objectives…

Abstract

Purpose

To introduce the Innovative Electronics Manufacturing Research Centre Flagship Project: Integrated Optical and Electronic Interconnect PCB Manufacturing, its objectives, its consortium of three universities and ten companies and to describe the university research being carried out. This paper briefly reviews the motivation for developing novel polymer formulations, fabrication techniques, layout design rules and characterisation techniques for hybrid electronic and optical printed circuit boards (PCBs) using multimode polymer optical waveguide interconnects.

Design/methodology/approach

The authors are investigating a number of different fabrication techniques which they compare with each other and with modelled calculations of waveguide components. The fabrication techniques include photolithography, laser ablation, direct laser writing, embossing, extrusion and ink jet printing.

Findings

A number of design rules for polymer multimode waveguides have been found and published. Techniques for ink jetting polymer to print waveguides and laser ablation techniques have been developed. New formulations of polymer which cure faster for direct writing have also been developed.

Research limitations/implications

Further work is needed to thicken the ink jet printed polymer and to investigate side wall roughness of the ablated waveguides and development of new polymer formulations for dry film. Further research is also needed on construction of prototype system demonstrators.

Practical implications

The fabrication techniques being developed are designed to be transferred to industrial PCB manufacturers to enable them to make higher value optical PCBs. The design rules being discovered are being entered into commercial PCB layout software to aid designers of optical PCBs.

Originality/value

The paper is of interest to PCB manufacturers who wish to upgrade their processes to be able to manufacture optical PCBs. The university research is original and some has been published as shown in the publications in the reference list.

Details

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

Keywords

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Article
Publication date: 1 April 2000

David A. Hutt, Daniel G. Rhodes, Paul P. Conway, Samjid H. Mannan, David C. Whalley and Andrew S. Holmes

As the demand for flip‐chip products increases, the need for low cost high volume manufacturing processes also increases. Currently solder paste printing is the wafer…

Abstract

As the demand for flip‐chip products increases, the need for low cost high volume manufacturing processes also increases. Currently solder paste printing is the wafer bumping method of choice for device pitches down to 150‐200μm. However, limitations in print quality and stencil manufacture mean that this technology is not likely to move significantly below this pitch and new methods will be required to meet the demands predicted by the technology roadmaps. This paper describes experiments conducted on carriers made from silicon for bumping of die using solder paste. An anisotropic etching process was used to generate pockets in the silicon surface into which solder paste was printed. Die were then placed against the carrier and reflowed to transfer the solder directly to the bondpads. An assessment was carried out of the potential application and limitations of this technique for device pitches at 225 and 127μm.

Details

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

Keywords

Content available
Article
Publication date: 3 February 2012

Martin Goosey

Abstract

Details

Circuit World, vol. 38 no. 1
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 1 March 1992

John Conway O'Brien

A collection of essays by a social economist seeking to balanceeconomics as a science of means with the values deemed necessary toman′s finding the good life and society…

Abstract

A collection of essays by a social economist seeking to balance economics as a science of means with the values deemed necessary to man′s finding the good life and society enduring as a civilized instrumentality. Looks for authority to great men of the past and to today′s moral philosopher: man is an ethical animal. The 13 essays are: 1. Evolutionary Economics: The End of It All? which challenges the view that Darwinism destroyed belief in a universe of purpose and design; 2. Schmoller′s Political Economy: Its Psychic, Moral and Legal Foundations, which centres on the belief that time‐honoured ethical values prevail in an economy formed by ties of common sentiment, ideas, customs and laws; 3. Adam Smith by Gustav von Schmoller – Schmoller rejects Smith′s natural law and sees him as simply spreading the message of Calvinism; 4. Pierre‐Joseph Proudhon, Socialist – Karl Marx, Communist: A Comparison; 5. Marxism and the Instauration of Man, which raises the question for Marx: is the flowering of the new man in Communist society the ultimate end to the dialectical movement of history?; 6. Ethical Progress and Economic Growth in Western Civilization; 7. Ethical Principles in American Society: An Appraisal; 8. The Ugent Need for a Consensus on Moral Values, which focuses on the real dangers inherent in there being no consensus on moral values; 9. Human Resources and the Good Society – man is not to be treated as an economic resource; man′s moral and material wellbeing is the goal; 10. The Social Economist on the Modern Dilemma: Ethical Dwarfs and Nuclear Giants, which argues that it is imperative to distinguish good from evil and to act accordingly: existentialism, situation ethics and evolutionary ethics savour of nihilism; 11. Ethical Principles: The Economist′s Quandary, which is the difficulty of balancing the claims of disinterested science and of the urge to better the human condition; 12. The Role of Government in the Advancement of Cultural Values, which discusses censorship and the funding of art against the background of the US Helms Amendment; 13. Man at the Crossroads draws earlier themes together; the author makes the case for rejecting determinism and the “operant conditioning” of the Skinner school in favour of the moral progress of autonomous man through adherence to traditional ethical values.

Details

International Journal of Social Economics, vol. 19 no. 3/4/5
Type: Research Article
ISSN: 0306-8293

Keywords

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Article
Publication date: 1 May 1983

In the last four years, since Volume I of this Bibliography first appeared, there has been an explosion of literature in all the main functional areas of business. This…

Abstract

In the last four years, since Volume I of this Bibliography first appeared, there has been an explosion of literature in all the main functional areas of business. This wealth of material poses problems for the researcher in management studies — and, of course, for the librarian: uncovering what has been written in any one area is not an easy task. This volume aims to help the librarian and the researcher overcome some of the immediate problems of identification of material. It is an annotated bibliography of management, drawing on the wide variety of literature produced by MCB University Press. Over the last four years, MCB University Press has produced an extensive range of books and serial publications covering most of the established and many of the developing areas of management. This volume, in conjunction with Volume I, provides a guide to all the material published so far.

Details

Management Decision, vol. 21 no. 5
Type: Research Article
ISSN: 0025-1747

Keywords

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Article
Publication date: 1 January 1979

In order to succeed in an action under the Equal Pay Act 1970, should the woman and the man be employed by the same employer on like work at the same time or would the…

Abstract

In order to succeed in an action under the Equal Pay Act 1970, should the woman and the man be employed by the same employer on like work at the same time or would the woman still be covered by the Act if she were employed on like work in succession to the man? This is the question which had to be solved in Macarthys Ltd v. Smith. Unfortunately it was not. Their Lordships interpreted the relevant section in different ways and since Article 119 of the Treaty of Rome was also subject to different interpretations, the case has been referred to the European Court of Justice.

Details

Managerial Law, vol. 22 no. 1
Type: Research Article
ISSN: 0309-0558

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