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Article
Publication date: 8 February 2011

Andrew J. Cobley, Lindsay Edgar, Martin Goosey, Rod Kellner and Timothy J. Mason

Previous studies have proven that, under optimised ultrasonic conditions, a range of materials used in electronic manufacturing can be sonochemically surface modified using benign…

Abstract

Purpose

Previous studies have proven that, under optimised ultrasonic conditions, a range of materials used in electronic manufacturing can be sonochemically surface modified using benign solutions at low temperature. The purpose of this paper is to focus on a specific process, namely, the desmearing of through holes in printed circuit boards (PCB). The objective was to determine whether the introduction of low frequency ultrasound (20 kHz) to the “etch” stage of a standard “swell and etch” desmear system could enable reduced temperature processing and the use of less chemistry in the permanganate solution.

Design/methodology/approach

The study was divided into three main stages. In the first “screening” phase, the effect of ultrasound in the etch solution was studied by measuring the weight loss after desmear on a PCB laminate material (Isola 370HR). Factors such as etch temperature and concentration of permanganate (including permanganate‐free) were varied. In stage 2, confirmatory runs were carried out on the most promising conditions from the screening work and through holes in a four‐layer multi‐layer board (MLB) were assessed for smear removal using a scanning electron microscope (SEM). Finally, a four‐layer MLB was desmeared through the most promising ultrasonic process and then metallized at a PCB manufacturer. Thermal shock testing was subsequently carried out and sections from the board assessed for inter‐connection defects (ICDs).

Findings

The initial screening study indicated that, whenever ultrasound was used in the etch stage of the desmear process, significantly higher weight loss was achieved compared to a standard “silent” process. This effect was most pronounced when permanganate was removed from the etch solution and, in this situation, weight loss could be an order of magnitude higher than the silent equivalent. Further testing on through holes suggested that smear‐free inner‐layers could only be guaranteed if permanganate was present in the etch solution but that ultrasound again improved smear removal. Final testing under semi‐production conditions confirmed that, if ultrasound was employed in the etch part of the desmear process, then a reduction in processing temperature from 85°C to 60°C could be achieved and the permanganate concentration halved (65 to 33 g/L) whilst still achieving ICD‐free boards.

Originality/value

The paper indicates the feasibility of using ultrasound to reduce temperatures and chemical concentrations used in the permanganate etch solution, whilst still producing through holes with no ICDs.

Details

Circuit World, vol. 37 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 3 February 2012

Andrew J. Cobley and Veronica Saez

Electroless plating is an important process in printed circuit board and electronics manufacturing but typically requires temperatures of 70‐95°C to give a suitable deposition…

Abstract

Purpose

Electroless plating is an important process in printed circuit board and electronics manufacturing but typically requires temperatures of 70‐95°C to give a suitable deposition rate. This is becoming problematic in industry due to the rising price of energy and is a major contribution to production costs. Previous studies have noted beneficial effects of ultrasonic irradiation upon electroless plating processes and it has been reported that sonication can increase the plating rate and produce changes to the chemical and physical properties of the deposited coating. The purpose of this paper is to reduce the operating temperature of an electroless nickel bath by introducing ultrasound to the process.

Design/methodology/approach

The deposition rate of an electroless nickel solution was determined by two techniques. In the first method, test coupons were plated in an electroless nickel solution at temperatures ranging from 50‐90°C and the plating rate was calculated by weight gain. In the second approach the mixed potential (and hence the current density at the mixed potential) was determined by electrochemical analysis of the anodic and cathodic reactions. In both cases the plating rate was found with and without the application of an ultrasonic field (20 kHz). The electroless nickel deposits obtained in the plating tests were also analysed to determine the phosphorus content, microhardness and brightness.

Findings

The plating rates under ultrasonic agitation were always higher than under “silent” conditions. Most importantly, considering the objectives of this study, the deposition rate under sonication at 70°C was significantly higher than that found with mechanical agitation at 90°C. In addition, the results indicated that the deposits produced in an ultrasonic field had consistently lower phosphorus content, higher microhardness and were brighter than those prepared in an electroless nickel bath that was not sonicated.

Originality/value

Although previous work has been performed on the effect of ultrasound on electroless plating, all these studies have been carried out at the normal operating temperature of the electroless process. In this paper, ultrasound has been applied at temperatures well below those normally used in electroless nickel deposition to determine whether sonication can enable low temperature electroless plating.

Details

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

Keywords

Content available
Article
Publication date: 3 February 2012

Martin Goosey

278

Abstract

Details

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

Content available
Book part
Publication date: 14 December 2023

Abstract

Details

Digitisation, AI and Algorithms in African Journalism and Media Contexts
Type: Book
ISBN: 978-1-80455-135-6

Article
Publication date: 13 August 2018

Andrew Iliadis and Isabel Pedersen

This paper aims to examine how metadata taxonomies in embodied computing databases indicate context (e.g. a marketing context or an ethical context) and describe ways to track the…

Abstract

Purpose

This paper aims to examine how metadata taxonomies in embodied computing databases indicate context (e.g. a marketing context or an ethical context) and describe ways to track the evolution of the embodied computing industry over time through digital media archiving.

Design/methodology/approach

The authors compare the metadata taxonomies of two embodied computing databases by providing a narrative of their top-level categories. After identifying these categories, they describe how they structure the databases around specific themes.

Findings

The growing wearables market often hides complex sociotechnical tradeoffs. Marketing products like Vandrico Inc.’s Wearables Database frame wearables as business solutions without conveying information about the various concessions users make (about giving up their data, for example). Potential solutions to this problem include enhancing embodied computing literacy through the construction of databases that track media about embodied computing technologies using customized metadata categories. Databases such as FABRIC contain multimedia related to the emerging embodied computing market – including patents, interviews, promotional videos and news articles – and can be archived through user-curated collections and tagged according to specific themes (privacy, policing, labor, etc.). One of the benefits of this approach is that users can use the rich metadata fields to search for terms and create curated collections that focus on tradeoffs related to embodied computing technologies.

Originality/value

This paper describes the importance of metadata for framing the orientation of embodied computing databases and describes one of the first attempts to comprehensively track the evolution of embodied computing technologies, their developers and their diverse applications in various social contexts through media archiving.

Details

Journal of Information, Communication and Ethics in Society, vol. 16 no. 3
Type: Research Article
ISSN: 1477-996X

Keywords

Article
Publication date: 1 June 1958

ELSEWHERE in this number we list libraries which have Esent us copies of their annual reports which we are glad to have. Now and again we are able to elaborate on these, but in…

Abstract

ELSEWHERE in this number we list libraries which have Esent us copies of their annual reports which we are glad to have. Now and again we are able to elaborate on these, but in the present issue that has not been possible. We would say, however, that these reports are deserving of the attention of librarians generally, and of students at the library schools. They are records of work in progress, and they do suggest the development of library policy. The best of them are of textbook value.

Details

Library Review, vol. 16 no. 6
Type: Research Article
ISSN: 0024-2535

Content available
Article
Publication date: 27 November 2007

J.H. Ling

251

Abstract

Details

Circuit World, vol. 33 no. 4
Type: Research Article
ISSN: 0305-6120

Article
Publication date: 28 August 2007

Andy Cobley and Tim Mason

This paper sets out to give an introduction to sonochemistry and the effects brought about by the application of ultrasound that might be useful in surface modification; and to…

Abstract

Purpose

This paper sets out to give an introduction to sonochemistry and the effects brought about by the application of ultrasound that might be useful in surface modification; and to show the feasibility of sonochemical surface modification in water on a range of materials employed in electronic manufacturing.

Design/methodology/approach

Ultrasound was applied through DI water for the surface modification of four materials: a ceramic, a polyphenylene ester (polystyrene polymer (Noryl HM4025)), an acrylonitrile‐butadiene‐styrene/polycarbonate (ABS/PC‐Cycolac S705), and an FR4 laminate (Isola Duraver 104). The efficacy of the treatment was determined by weight loss, scanning electronic microscopy, contact angle and roughness.

Findings

Ceramic and Noryl materials can be surface modified sonochemically in DI water. Weight loss results suggested that, this was also the case for the Duraver laminate but the ABS/PC substrate was least affected by treatment in an ultrasonic field under these benign processing conditions.

Originality/value

Traditional “wet” surface modification techniques often use hazardous chemistry, high‐process temperatures, copious rinsing and long dwell times. This research programme addresses these issues by evaluating sonochemical surface modification techniques with the objective of producing a one‐step process using benign chemistry at lower temperature with less rinsing.

Details

Circuit World, vol. 33 no. 3
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 1 August 2005

Abstract

Details

The British Journal of Forensic Practice, vol. 7 no. 3
Type: Research Article
ISSN: 1463-6646

Article
Publication date: 1 May 2006

Nikolaos Th. Korfiatis, Marios Poulos and George Bokos

The purpose of this paper is to present an approach to evaluating contributions in collaborative authoring environments, and in particular, Wikis using social network measures.

7923

Abstract

Purpose

The purpose of this paper is to present an approach to evaluating contributions in collaborative authoring environments, and in particular, Wikis using social network measures.

Design/methodology/approach

A social network model for Wikipedia has been constructed, and metrics of importance such as centrality have been defined. Data has been gathered from articles belonging to the same topic using a web crawler, in order to evaluate the outcome of the social network measures in the articles.

Findings

Finds that the question of the reliability regarding Wikipedia content is a challenging one and as Wikipedia grows, the problem becomes more demanding, especially for topics with controversial views such as politics or history.

Practical implications

It is believed that the approach presented here could be used to improve the authoritativeness of content found in Wikipedia and similar sources.

Originality/value

This work tries to develop a network approach to the evaluation of Wiki contributions, and approaches the problem of quality Wikipedia content from a social network point of view.

Details

Online Information Review, vol. 30 no. 3
Type: Research Article
ISSN: 1468-4527

Keywords

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