scholarly journals An investigation of tin whisker growth over a 32-year period

Circuit World ◽  
2016 ◽  
Vol 42 (4) ◽  
pp. 183-196 ◽  
Author(s):  
Mark Andrew Ashworth ◽  
Barrie Dunn
Keyword(s):  
Cross Sections ◽  
Whisker Growth ◽  
Tin Whisker ◽  
Content Type ◽  
Intermetallic Formation ◽  
Time Period ◽  
Whisker Length ◽  
Electron Microscopy Analysis ◽  
Long Time ◽  
Tin Plating

Purpose This paper aims to present the results of a 32-year-old laboratory study of whisker growth from tin electrodeposits that was originally undertaken to gain an increased understanding of the phenomenon of tin whisker growth. Design/methodology/approach Whisker growth was evaluated using electroplated C-rings (both stressed and un-stressed) that were stored throughout in a desiccator at room temperature. Analysis has recently been undertaken to evaluate whisker growth and intermetallic growth after 32 years of storage. Scanning electron microscopy analysis has been performed to investigate whisker length and, using polished cross-sections, the morphology, thickness and type of intermetallic formation. Findings Normal tin-plated deposits on brass and steel with a copper barrier layer nucleated whiskers within five months, and in each case, these grew to lengths between 1 and 4.5 mm. For normal tin electroplated onto brass, a one- or two-month nucleation period was needed before whiskers developed. They reached a maximum length of about 1.5 mm after six months, and little or no further growth occurred during the subsequent 32 years. Very few whiskers grew on the tin-plated steel samples and no intermetallic formation was observed. None of the fused tin plating samples nucleated whiskers during the 32-year period. Practical implications Knowledge about vintage whiskers is important to take steps to increase the resiliency of space missions. Similarly, such knowledge is important to engineers engaged in products reaching their nominal end-of-life, but where, for reasons of economy, these products cannot be replaced. Originality/value This study represents a unique insight into whisker growth and intermetallic formation over an extremely long time period.

The changing pattern of UK strikes, 1964-2014

2015 ◽  
Vol 37 (6) ◽  
pp. 733-745 ◽  
Author(s):  
Dave Lyddon
Keyword(s):  
Design Methodology ◽  
Transition Period ◽  
Strike Activity ◽  
Content Type ◽  
The Third ◽  
Time Period ◽  
Long Time ◽  
Legislative Changes ◽  
The Uk

Purpose – The purpose of this paper is to provide an overview of the changing strike activity in the UK over the last 50 years. Design/methodology/approach – The paper draws on a wide literature on UK strikes and an extensive trawl of newspaper sources. It is divided into four main sections. The first two summarise, in turn, the changing amount and locus of strike activity between 1964 and 2014. The third discusses the changing relationship and balance between official and unofficial strikes. The last covers the role of the courts and legislation on strikes, highlighting some key moments in this turbulent history. Findings – The period 1964-2014 can be divided into three sub-periods: high-strike activity until 1979; a transition period of “coercive pacification” in the 1980s; and unprecedentedly low-strike activity since the early 1990s. Unions were more combative against the legislative changes of the 1980s than they are normally given credit for. Research limitations/implications – Given its broad scope, this paper cannot claim to be comprehensive. Originality/value – This is a rare study of the changing nature of UK strikes over such a long time period.

scholarly journals The Effects of Humidity on Tin Whisker Growth by Immersion Tin Plating and Tin Solder Dipping Surface Finishes

2015 ◽  
Vol 2 ◽  
pp. 275-279 ◽  
Author(s):  
Hooi Peng Lim ◽  
Ali Ourdjini ◽  
Tuty Asma Abu Bakar ◽  
Tuquabo Tesfamichael
Keyword(s):  
Whisker Growth ◽  
Tin Whisker ◽  
Surface Finishes ◽  
Tin Plating ◽  
Immersion Tin

Panel data comparative analysis on the influence of population age structure on the size of government expenditure in Africa and Asia

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Chukwuebuka Bernard Azolibe
Keyword(s):  
Cross Sections ◽  
Age Structure ◽  
Government Expenditure ◽  
Empirical Literature ◽  
Size Of Government ◽  
Population Age Structure ◽  
Content Type ◽  
Time Period ◽  
The World ◽  
Age Structures

PurposeAfrica and Asia are the two most populous continents in the world and are projected to increase further in the near future and this puts the governments under great stress in terms of increased public expenditure and dealing with a low revenue generation. Thus, the purpose of this study is to assess the influence of population age structure on the size of government expenditure in Africa and Asia covering the period 1990–2018.Design/methodology/approachThe study employed panel fully modified ordinary least squares (FMOLS) estimation in estimating the relevant relationship between the variables in the model.FindingsThe key findings revealed that the major population age structures that influence the size of government expenditure in Africa are population aged 0–14 years and population aged 15–64 years, while that of Asia are population aged 15–64 years and population aged 65 years and above. The findings provided strong support for the Population Reference Bureau report (2019) that countries in Africa are home to some of the world's youngest population, that is, those aged 15 years or below, while Asia is home to some of the world's oldest population, that is, those aged 65 years and above.Research limitations/implicationsWhile generalized method of moments (GMM) estimation is beneficial in the presence of endogeneity, it is only designed for situations with a small time period (T) and a large number of cross sections (N). Hence, the estimation technique was limited only to FMOLS as the number of the cross sections or countries which is ten for Africa and ten for Asia is lower than the time period which is 29 years (1990–2018).Originality/valueEmpirical literature investigating the influence of population age structure on the size of government expenditure has focussed mainly on one aspect of the population age structure and government expenditure, which is the influence of ageing population on government expenditure on health. Hence, this study focussed on assessing the influence of population age structure on the size of government expenditure. The study is unique as it compared the two most populous continents in the world, which are Africa and Asia to determine which of the population age structures have the most significant influence on the size of government expenditure.

The influence of porosity on whisker growth in electroplated tin films

2006 ◽  
Vol 21 (12) ◽  
pp. 2971-2974 ◽  
Author(s):  
J.P. Winterstein ◽  
M.G. Norton
Keyword(s):  
Whisker Growth ◽  
Control Method ◽  
Stress Relief ◽  
Lead Free ◽  
Tin Whisker ◽  
Tin Films ◽  
The Past ◽  
Compressive Stresses ◽  
Time Period ◽  
Lead Free Solders

Tin whisker growth has been observed since the 1950s and has become of more interest in the past 15 to 20 years due to the desire to use lead-free solders, pure tin being a good lead-free candidate. In the same time period, failure of satellites and other devices using pure tin solders has been blamed on tin whisker growth. The accepted driving force for whisker growth is compressive stresses in films. This article reports a microstructure-control method of limiting whisker growth through the introduction of pores that permit an alternate means of stress relief.

Corrosion-induced tin whisker growth in electronic devices: a review

2017 ◽  
Vol 29 (1) ◽  
pp. 59-68 ◽  
Author(s):  
Balázs Illés ◽  
Barbara Horváth ◽  
Attila Géczy ◽  
Olivér Krammer ◽  
Karel Dušek
Keyword(s):  
Literature Review ◽  
Whisker Growth ◽  
Electronic Devices ◽  
Lead Free ◽  
Future Research ◽  
Tin Whisker ◽  
Content Type ◽  
The Past ◽  
Surface Finishes ◽  
Inducing Factors

Purpose The aim of this paper is to present a review of the tin whisker growth phenomena. The study focuses mainly on whisker growth in a corrosive climate when the main inducing factor of the whisker growth is oxidation. The tin whisker phenomenon is still a big challenge in lead-free reflow soldering technology. Modern lead-free alloys and surface finishes with high tin content are considered to be possible sources of whisker development, also the evolution of electronic devices towards further complexity and miniaturization points to an escalation of the reliability risks. Design/methodology/approach The present work was based on a worldwide literature review of the substantial previous works in the past decade, as well as on the results and experience of the authors in this field. Findings The effect of corrosion on tin whisker growth has been under-represented in reports of mainstream research; however, in the past five years, significant results were obtained in the field which raised the corrosion phenomena from being a side effect category into one of the main inducing factors. This paper summarizes the most important findings of this field. Practical implications This literature review provides engineers and researchers with a better understanding of the role of corrosion in tin whisker growth and the current challenges in tin whisker mitigation. Originality/value The unique challenges and future research directions about the tin whisker phenomenon were shown to highlight rarely discussed risks and problems in lead-free soldering reliability.

Project cost control: a new method to plan and control costs in large projects

2016 ◽  
Vol 22 (6) ◽  
pp. 1247-1268 ◽  
Author(s):  
R. Jayaraman
Keyword(s):  
Cost Control ◽  
Cost Management ◽  
Roll Steel ◽  
Content Type ◽  
Steel Sheets ◽  
Time Period ◽  
Salutary Effect ◽  
Long Time ◽  
The Cost ◽  
And Control

Purpose The purpose of this paper is to reengineer the process of cost management in large projects. Design/methodology/approach Considering the fact most large projects overrun their budgets because of the long time period needed to completion, it was decided to reengineer the cost management. Accordingly costs allocated to packages were reviewed and changed on a dynamic basis. Different types of contingencies were provided. Concepts of package contingency and project contingency were introduced. These were based on the project buffer and feeding buffer concepts popularised by Eliyahu Goldratt. Findings The re-engineered method of cost control worked well and yielded better than expected results, leading to the setting up of a new world record in the completion time for setting up a million tonnes per annum continuous, tandem cold rolling mill to roll steel sheets. Research limitations/implications In view of the total success of the reengineered approach, which was tested out on a large project over three years, it is felt that other projects could also try out this technique, especially since it is along the lines proposed by Eliyahu Goldratt who is an authority on project management. However the success can be better understood if the results of the testing become available. To that extent the contents of the present paper have limitations. Practical implications Large projects can deploy the methodology and complete their projects on time and under budget. Social implications The reengineering of the cost management was done primarily with a view to complete projects under budget. Since many governments spend many billions of dollars on publicly funded projects for the welfare of citizens, the use of this technique could have a salutary effect on the cost. Originality/value The method was innovated in the company by the author’s team and deployed in a live project over four years for the first time to achieve world-class results.

Survival in fast-changing markets

2015 ◽  
Vol 31 (1) ◽  
pp. 18-20
Keyword(s):  
Middle Managers ◽  
Business Leaders ◽  
Strategy Development ◽  
Content Type ◽  
Emergent Strategy ◽  
Time Period ◽  
Performance Effects ◽  
Long Time ◽  
Market Opportunities ◽  
Strategy Making

Purpose – The purpose of this paper is to find out if the approach to strategy-making taken by small to medium-sized enterprises (SMEs) affects their performance. Design/methodology/approach – This paper reports findings from a longitudinal study of small Austrian manufacturing firms. It investigates their use of deliberate or emergent strategy-making and how this affected market development and product innovation. Findings – When you think about strategy development, perhaps you think of long, serious discussions between groups of managers. But what if the organization is a small business? Leaders of SMEs do not have that option. So if an SME starts a new initiative – product development, say, or a change of marketing approach – how does this happen? Is it planned by the entrepreneur? Or – if you do not have middle managers with time to spend on strategy development – does adopting a “try it and see” approach give better results? Research limitations/implications – It demonstrates the benefits of a longitudinal investigation of the performance effects of deliberate and emergent strategy development. Practical implications – It shows how the use of emergent or deliberate approaches to strategy development is linked to SME performance. Social implications – It highlights the benefits of using diverse information sources – including customers and employees – as an integral part of strategy-making to identify market opportunities and trends. Originality/value – It covers an unusually long time period, enabling researchers to compare firm performance in stable and dynamic market conditions.

The Effects of Nickel Underlayer and Solder Dipping as Tin Whisker Mitigations in Tin Surface Finishes

2014 ◽  
Vol 554 ◽  
pp. 47-51
Author(s):  
Hooi Peng Lim ◽  
Ali Ourdjini ◽  
Tuty Asma Abu Bakar
Keyword(s):  
Whisker Growth ◽  
Hazardous Substances ◽  
Lead Free ◽  
Bending Test ◽  
Tin Whisker ◽  
Surface Finishes ◽  
Whisker Length ◽  
External Stresses ◽  
Pure Sn

Driven by environmental concerns and the enforcement of Restriction of Hazardous Substances Directive (RoHS) to ban the use of lead in electronics, the global electronics industry has migrated toward lead-free electronics. However, the adoption of lead-free tin (Sn) surface finish is known to form whiskers. These whiskers grow spontaneously from the Sn finish layer as a stress-relief over time causing device failures. In the present research, whisker growth is investigated via immersion Sn finishes on Cu substrate. The effects of Sn layer thickness, addition of Ni under-layer and solder dipping on whisker growth are investigated by storing the samples under ambient temperature for up to 24 weeks. The effects of external stresses were also studied using bending test. The results showed that whisker length on immersion Sn increases with time for all the samples either with or without Ni under-layer. Thicker Sn coating showed more whisker growth compared with thinner Sn coating. The longest whisker length of 23μm was observed for Sn coating with 2μm thickness. The addition of Ni as under-layer was found to be more effective in mitigating the whisker growth by extending the incubation time for whisker formation. Compared to immersion Sn, solder dipping in pure Sn showed no whisker growth. However, alloying Sn with 0.4%wtCu resulted in whisker growth indicating the role of Cu in promoting whiskers formation.

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