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Article
Publication date: 18 September 2009

D. Di Maio and C.P. Hunt

The purpose of this paper is to investigate the various factors that influence the dissolution of copper in molten solder, paying particular attention to important parameters…

387

Abstract

Purpose

The purpose of this paper is to investigate the various factors that influence the dissolution of copper in molten solder, paying particular attention to important parameters: temperature, solder composition and flow rate.

Design/methodology/approach

To determine the dissolution rate of copper in lead‐free solders, a simple and automated technique is developed. This methodology provides repeatable measurements that allow the various experimental parameters to be isolated. Factors that greatly affect the dissolution rate of copper, such as soldering temperature, flow rate and solder composition, are taken into account. Particular attention is paid to the flow rate of the molten solder. In fact, different alloys at the same temperature can have considerably different flow rates, owing to their different viscosities at that temperature. The dissolution rates of copper in seven lead‐free alloys and the Sn‐Pb alloy are compared at 255, 275 and 300°C.

Findings

It is observed that generally the samples with a thicker intermetallic layer are those that exhibit a longer dissolution time.

Originality/value

The transition from tin‐lead to lead‐free increases the tendency for copper dissolution in molten solders, clearly representing a serious risk to circuit reliability. This paper presents the many advantages of a method for comparing the dissolution rate of copper with different solder alloys.

Details

Soldering & Surface Mount Technology, vol. 21 no. 4
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 1 January 1954

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Council, Reports and Technical Memoranda of the United States…

23

Abstract

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Council, Reports and Technical Memoranda of the United States National Advisory Committee for Aeronautics and publications of other similar Research Bodies as issued

Details

Aircraft Engineering and Aerospace Technology, vol. 26 no. 1
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 15 February 2011

Vishanth Weerakkody, Ramzi El‐Haddadeh and Shafi Al‐Shafi

The purpose of this paper is to explore empirically the complexities of e‐government implementation and diffusion from a developing country perspective.

3463

Abstract

Purpose

The purpose of this paper is to explore empirically the complexities of e‐government implementation and diffusion from a developing country perspective.

Design/methodology/approach

An empirical case study using an interview‐based research agenda is adopted. After reviewing the extant literature on e‐government, the paper first proposes a conceptual model, which is consequently used to explore empirically, within the State of Qatar, the key challenges influencing e‐government implementation and diffusion from organisational, technological, social and political perspectives.

Findings

The conceptual model proposed in this study offers a comprehensive overview of the implementation and diffusion challenges of e‐government through identifying various factors associated with organisational, technological, social and political perspectives from the literature. Through adopting an empirical research strategy focusing on developing countries that are not in an advanced state of e‐government development, this study offers a holistic view in understanding e‐government implementation and diffusion complexities for the benefit of similar countries.

Research limitations/implications

This research only focuses on exploring empirically the implementation and diffusion challenges facing e‐government in one developing country and does not investigate how these challenges may influence citizens' adoption of these services in that country or in a wider context.

Practical implications

The conceptual model in this study offers practitioners, policy makers and researchers a comprehensive overview of the implementation and diffusion challenges of e‐government projects, particularly in developing countries. The key findings of this study show that, irrespective of strong financial support and resources, governments must be prepared to tackle a number of challenges related to the complexity of e‐government implementation and diffusion. In addition, the study indicates that better alignment of national ICT strategies with various local level e‐government projects, clear legislation, implementation guidelines and standards are imperative for e‐government success.

Originality/value

The core contribution of this research adds to the growing body of knowledge concerning the implementation and diffusion of e‐government in developing countries. In particular, the conceptual model formulated through the synthesis of extant literature offers researchers and practitioners a lens to better appreciate the key challenges that require consideration when implementing and diffusing e‐government.

Details

Journal of Enterprise Information Management, vol. 24 no. 2
Type: Research Article
ISSN: 1741-0398

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Article
Publication date: 9 February 2010

W.J. Plumbridge

The purpose of this paper is to describe the effects of mechanical testing and thermal treatment prior to storage at either −18 or −40°C, for periods in excess of ten years on the…

319

Abstract

Purpose

The purpose of this paper is to describe the effects of mechanical testing and thermal treatment prior to storage at either −18 or −40°C, for periods in excess of ten years on the Sn‐37Pb alloy.

Design/methodology/approach

For over a decade, The Solder Research Group at The Open University has studied tin pest development in several of the new lead‐free solders. Bulk samples, employed for mechanical testing, are laid down at −18 and −40°C, and inspected periodically.

Findings

In a previous examination in 2006, there was no evidence of tin pest formation in this alloy. On re‐examination of the same specimens in 2008, about one in ten of the samples stored at −18°C, both “as cast” and “tested”, exhibited warts of tin pest. Storage at −40°C increased this ratio to about one in three following treatment.

Originality/value

The paper's findings demonstrate that, even with high concentrations of lead present, eventually tin pest will form. So, for interconnections used in long‐term applications, whether lead‐free or lead‐bearing solders are employed, performance and structural integrity considerations should not ignore tin pest.

Details

Soldering & Surface Mount Technology, vol. 22 no. 1
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 7 April 2015

Mohammad Faizan

– The purpose of this paper was to develop a physics-based mathematical model to estimate the amount of substrate metal lost during the wet soldering process.

153

Abstract

Purpose

The purpose of this paper was to develop a physics-based mathematical model to estimate the amount of substrate metal lost during the wet soldering process.

Design/methodology/approach

A mathematically rigorous model depicting the actual physics of the substrate/solder interaction and dissolution has been proposed to simulate the dissolution of the substrate metal in the liquid lead-free solder. The basic mass diffusion equation with the implementation of interface reaction kinetics was solved numerically using the finite volume approach. The moving interface was tracked by utilizing the coordinate transformation technique.

Findings

It was observed that the process of metal dissolution in the liquid solder was governed by two important parameters, viz., interface kinetics and long-range diffusion in the liquid solder. Non-equilibrium behavior was observed in the early stage of the process. The early stage of the dissolution process was seen as governed by interface kinetics, while diffusion became the rate-controlling mechanism at the later phase of soldering.

Practical implications

Substrate dissolution can be accurately estimated for a particular substrate–solder combination and for the given process conditions. This early estimation will help in ensuring the reliability and health of the solder joint.

Originality/value

A model based on actual physics is proposed, and interface reaction kinetics has been introduced to capture the actual behavior of the process. The model will serve as the basis for two- and three-dimensional analysis, including the formation of an intermetallic compound in the solder joint.

Details

Soldering & Surface Mount Technology, vol. 27 no. 2
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 14 February 2018

Zuozhu Yin, Fenglian Sun, Yang Liu and Yang Liu

The purpose of this paper is to investigate growth kinetics of interfacial Cu-Sn intermetallic compound (IMC) at the solid Cu/liquid Sn interface.

246

Abstract

Purpose

The purpose of this paper is to investigate growth kinetics of interfacial Cu-Sn intermetallic compound (IMC) at the solid Cu/liquid Sn interface.

Design/methodology/approach

The Sn/Cu solid–liquid interfacial IMCs are fabricated under various soldering temperatures (240°C-270°C) and soldering times (5-240 s) by dipping method. The thickness and morphology of IMC are observed and analyzed by the optical microscope and scanning electron microscope.

Findings

Holding at 260°C, Cu/Sn solid–liquid interface Cu6Sn5 growth index experience a change from 0.08 to 0.30 within 10-190 s. The growth index is 0.08 in 10-40 s; the growth index is 0.30 in 40-190 s. Cu6Sn5 grain coarsening index is constant within 10-190 s. It is 0.13. The result of the index of Cu6Sn5 grain coarsening is different from predecessors 27 results Cu6Sn5 grain coarsening index for 1/3. This is because Cu6Sn5 grain grows at the expense of its near small grain to reduce the surface Gibbs free energy, and its morphology changes from regular shape to irregular shape. It sets up the mathematical expression about the initial formation time and temperature of Cu3Sn in 240°C-270°C.

Originality/value

It obtains a mathematical model to express the changes of solid–liquid interface frontier concentration which has an effect on the interfacial Cu6Sn5 layer growth index and the Cu6Sn5 grain coarsening index. Different indexes can be obtained by establishing relevance equations, which can be used to predict the growth of the interface IMC layer. This mathematical model is established to design the solder pads and the sizes of the solder joints.

Details

Soldering & Surface Mount Technology, vol. 30 no. 3
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 27 May 2014

Agata Skwarek, Jan Kulawik, Andrzej Czerwinski, Mariusz Pluska and Krzysztof Witek

The purpose of this study is to develop a testing method for tin pest in tin – copper (SnCu) alloys. Tin pest is the allotropic transformation of white β-tin (body-centered…

1005

Abstract

Purpose

The purpose of this study is to develop a testing method for tin pest in tin – copper (SnCu) alloys. Tin pest is the allotropic transformation of white β-tin (body-centered tetragonal structure) into gray α-tin (diamond cubic structure) at temperatures < 13.2°C.

Design/methodology/approach

Bulk samples of Sn99Cu1 weight per cent (purity, 99.9 weight per cent) were cast in the form of roller-shaped ingots with a diameter of 1.0 cm and a height of 0.7 cm. The samples were then divided into four groups. The first group included samples artificially inoculated with α-tin powder. The second group was inoculated in the same way as the samples from the first group but additionally subjected to mechanical pressing. The third group of ingots was only subjected to mechanical pressing. The fourth group of samples consisted of as-received roller-shaped ingots.All samples were divided into two groups and kept either at −18°C or at −30°C for the low-temperature storage test. For tin pest identification, a visual inspection was made, using a Hirox digital microscope over 156 days at intervals not longer than 14 days. The plot of the transformation rate, presented as the average increase in the area of α-tin warts in time, was also determined. To demonstrate the differences between regions of β- and α-tin, scanning ion microscopy observations using the focused ion beam technique was performed.

Findings

The first symptoms of tin pest were observed for the inoculated, mechanically pressed samples stored at −18°C, as well as those at −30°C, after less than 14 days. In the first stage of transformation, the rate was higher at −30°C for some time but, after about 75 days of storage at sub-zero temperatures, the rate at −30°C became lower compared to the rate at −18°C. Inoculation via the application of substances which are structurally similar to α-tin was efficient for the proposed new approach of rapid testing only when applied with simultaneous mechanical pressing. Infection from pressed-in seeds, leading to conventional seeded growth, was more rapid than infection in contact with seeds (without mechanical pressing), where the transition mechanism was induced by the epitaxial growth of metastable ice.

Originality/value

The new rapid method for the diagnostic testing of the susceptibility of different SnCu alloys to tin pest in a period much shorter than 14 days (within single days for storage at −30°C) is proposed and described. The test procedure described in this paper produced results several times quicker than conventional procedures, which may take years. In effect, the behavior of tin alloys in the face of tin pest may be predicted much more easily and much earlier. The same procedure can be applied to other SnCu alloys used in electronics (and in other areas), if the test samples are prepared in a similar manner.

Details

Soldering & Surface Mount Technology, vol. 26 no. 3
Type: Research Article
ISSN: 0954-0911

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Available. Content available
Article
Publication date: 18 September 2009

Martin Goosey

249

Abstract

Details

Soldering & Surface Mount Technology, vol. 21 no. 4
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 9 April 2018

Mehdi Akhondizadeh, Majid Fooladi Mahani, Masoud Rezaeizadeh and Hoseyn S. Mansouri

Oblique impacts which occur in many situations in mineral industries leads to material removal and fail of mechanical parts. Studies will be helpful in optimal design to have…

195

Abstract

Purpose

Oblique impacts which occur in many situations in mineral industries leads to material removal and fail of mechanical parts. Studies will be helpful in optimal design to have minimum machine malfunctions.

Design/methodology/approach

In the present work, the Hertz-Di Maio Di Renzo nonlinear model of contact is used to simulate the impact phenomenon as a micro-sliding process. The modified Archard equation is used to evaluate wear over the impact. The wear coefficient is evaluated by a pin-disk machine. An impact-wear tester is used to validate the model results.

Findings

The measurements indicate an increase in surface hardness because of the several impacts. It is considered in the wear predictive model.

Originality/value

The model predictions compared with the experimental data, obtained from the impact-wear tester, show that the model well predicts the impact wear and can be used as a predictive tool to study the practical design problems and to explain some phenomena associated with the percussive impact.

Details

Industrial Lubrication and Tribology, vol. 70 no. 3
Type: Research Article
ISSN: 0036-8792

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Book part
Publication date: 9 June 2020

Andrés Marroquín

Do business owners hold capitalist beliefs – relative to non-business owners? Using Latinobarómetro survey in Latin America, we find that business owners tend to see the market…

Abstract

Do business owners hold capitalist beliefs – relative to non-business owners? Using Latinobarómetro survey in Latin America, we find that business owners tend to see the market economy as the only system by which a country can become developed. They also tend to give a lower rank to Fidel Castro, and tend to believe that sole private investment in sectors like hospitals and pensions are good for the country to develop as soon as possible. But, business owners do not see foreign capital as good in industries such as mining, electronics, household appliances, automobile, telecommunication services, and infrastructure. They also do not see foreign investment as beneficial for economic development of the country. In addition, they are less willing to adopt some new technologies.

Details

Anthropological Enquiries into Policy, Debt, Business, and Capitalism
Type: Book
ISBN: 978-1-83909-659-4

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