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The Comparative Study of Conscription in the Armed Forces
Type: Book
ISBN: 978-0-76230-836-1

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B.P. Richards, P.K. Footner and P. Burton

The effect of ultrasonic agitation on hybrid devices during PCB cleaning has long been suspected as leading to device malfunction. However, little or no data exist to…

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The effect of ultrasonic agitation on hybrid devices during PCB cleaning has long been suspected as leading to device malfunction. However, little or no data exist to substantiate or quantify these effects. This paper describes a limited study into these effects using both test vehicles and commercial products, and discusses their variation with exposure time, the types and mechanisms of failure, and the rle of the hybrid package construction. It is demonstrated that the design of the hybrid package is critical in determining its susceptibility to ultrasonic damage.

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Circuit World, vol. 19 no. 1
Type: Research Article
ISSN: 0305-6120

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B.P. Richards, P. Burton and P.K. Footner

Although the use of ultrasonic agitation on quartz crystal devices during PCB cleaning has long been suspected to be detrimental, little or no data exist to substantiate…

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Although the use of ultrasonic agitation on quartz crystal devices during PCB cleaning has long been suspected to be detrimental, little or no data exist to substantiate or quantify the resultant effects. This paper summarises the results of a limited study into these effects for a range of quartz crystal devices, using both CFC and aqueous solvents. The variations with exposure time, and the types and mechanisms of failure are discussed. The results are encouraging and suggest that, although these devices are more susceptible to damage than ICs, once manufacturing defects have been screened out they will withstand ultrasonic exposure without deleterious effects for periods several times longer than those used for cleaning PCBs.

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Circuit World, vol. 18 no. 4
Type: Research Article
ISSN: 0305-6120

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B.P. Richards, P. Burton and P.K. Footner

The effects of ultrasonic agitation on electronic components during PCB cleaning has long been the subject of controversy. This paper summarises the results of a series of…

Abstract

The effects of ultrasonic agitation on electronic components during PCB cleaning has long been the subject of controversy. This paper summarises the results of a series of studies into these effects for a range of components using CFC, aqueous and semi‐aqueous cleaning media. The variations with exposure time and power density under various ultrasonic stress conditions (loose, mounted on PCBs, or on purpose‐built test boards) are discussed. The results are encouraging and suggest that there is a large margin of safety when employing currently accepted regimes of operation and good quality components. However, the strong dependence of the damage accumulation on power density emphasises the need to specify and tightly control the power density used.

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Circuit World, vol. 17 no. 4
Type: Research Article
ISSN: 0305-6120

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B.P. Richards, P.K. Footner, D.J. Prichard and C. Lea

With the advent of the Montreal Protocol, the removal of flux residues from printed circuit assemblies using solvents based on CFC‐113 is no longer an acceptable option…

Abstract

With the advent of the Montreal Protocol, the removal of flux residues from printed circuit assemblies using solvents based on CFC‐113 is no longer an acceptable option. An alternative range of cleaning technologies is being developed and marketed for this purpose, and the aim of this work was to study the efficiency of a variety of these alternative cleaning regimes after IR reflow soldering. The results indicated that: (i) all the cleaning regimes were capable of removing flux and flux residues after standard IR reflow soldering; (ii) as the level of flux contamination under the components increased, the ability of the cleaning regimes to clean the boards decreased; (iii) the cleaning regimes had varying problems in removing the flux residues after the non‐standard (overheat) IR profile processing; (iv) when additional flux is introduced under the components (i.e., non‐standard IR reflow), the delay between soldering and cleaning becomes important; and (v) the cleaning regimes exhibited a wide variation in their ability to clean under components with small stand‐off heights.

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Circuit World, vol. 19 no. 3
Type: Research Article
ISSN: 0305-6120

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B.P. Richards, P. Burton and P.K. Footner

An investigation of the use of ultrasonic agitation for cleaning printed circuit boards using CFC‐based solvents has shown that, under the standard conditions required to…

Abstract

An investigation of the use of ultrasonic agitation for cleaning printed circuit boards using CFC‐based solvents has shown that, under the standard conditions required to produce clean assemblies, no damage will occur to the components studied. Damage can only be induced by use of anomalously longer times or higher power densities. In all cases in which damage has been induced, it is of a purely mechanical nature due to fatigue, and is located on the device bond‐wires and/or the package legs. Cleaning using CFC‐based solvents under standard ultrasonic conditions of power density and time etc. is readily achieved within 2 minutes, even with a minimum stand‐off height.

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Circuit World, vol. 16 no. 3
Type: Research Article
ISSN: 0305-6120

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Gordon Wills, Jacqueline Hodgson, Christine Pearce, Phil Phillips and David Walters

This Symposium reports on the opportunities available to those who take the initiative to introduce materials management approaches. It examines both the anticipate rates…

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This Symposium reports on the opportunities available to those who take the initiative to introduce materials management approaches. It examines both the anticipate rates of change and development of the underlying factors as well as the organisational implications they entail. A full bibliography of recent literature is provided. The predicted developments are derived from the findings of a Delphi Study in association with the Institute of Purchasing and Supply conducted by the author in 1976.

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International Journal of Physical Distribution, vol. 8 no. 1
Type: Research Article
ISSN: 0020-7527

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J.H. Vincent, B.P. Richards, D.R. Wallis, I.A. Gunter, M. Warwick, H.A.H. Steen, P.G. Harris, M.A. Whitmore, S.R. Billington, A.C. Harman and E. Knight

This is the second of two papers reporting work carried out under a programme sponsored by the Department of Trade and Industry (DTI), involving collaboration between the…

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This is the second of two papers reporting work carried out under a programme sponsored by the Department of Trade and Industry (DTI), involving collaboration between the above companies and research centres. The objectives of the programme are to identify/develop lead‐free alternatives to Sn‐40Pb solder, progress towards the development of which is described in this paper. A number of promising alloys have been selected for trial in a further round of experimentation.

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Circuit World, vol. 19 no. 3
Type: Research Article
ISSN: 0305-6120

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Article

Brian Richards

‘The Joining Environment’ Dates: 14–15 October 1992 Venue: Forte Posthouse, Coventry, England This Conference will provide a venue for discussion on advances in joining…

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‘The Joining Environment’ Dates: 14–15 October 1992 Venue: Forte Posthouse, Coventry, England This Conference will provide a venue for discussion on advances in joining technology, and papers will cover a wide range of scientific and technical developments, focusing in particular on soldering, brazing and diffusion bonding practices which may involve environmental considerations.

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Soldering & Surface Mount Technology, vol. 4 no. 3
Type: Research Article
ISSN: 0954-0911

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Beverley Costa

Many people accessing services, including counselling services, do not speak the official language of the country in which they find themselves. This paper first…

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Many people accessing services, including counselling services, do not speak the official language of the country in which they find themselves. This paper first considers, in general terms, the way that language is used to negotiate relationships and to structure and provide meaning for our experiences, needs, feelings and ideas. This is then related to the use of native language in therapeutic work and the practical issues that this can present for services.The paper then reports on a small‐scale informal piece of research that was conducted in 2009 by Mothertongue multi‐ethnic counselling and listening service with six bilingual and multilingual counsellors, none of whom were native English speakers. The aim was to explore what might be learned from their experience of living with more than one language and then to apply this to the task of communicating in English with non‐English speakers in the therapeutic relationship.Some practical observations and suggestions are included in this paper. These incorporate the themes that emerged from the research such as: attending to clients' linguistic history; the way in which emotions are expressed in different languages; how speaking more than one language impacts on identity formation and the ability to understand across languages and culture; how we convey and construe significance and meaning; how we relate to people's experiences of learning a language. The author of this paper hopes that these findings and observations will stimulate further conversations on this topic.

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Ethnicity and Inequalities in Health and Social Care, vol. 3 no. 1
Type: Research Article
ISSN: 1757-0980

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