Esther Ngan-ling Chow and Yuchun Zou
Purpose – Integrating a gender perspective with a world-system theory, we examine how the recent global economic crisis in China has differential impact on female and male migrant…
Abstract
Purpose – Integrating a gender perspective with a world-system theory, we examine how the recent global economic crisis in China has differential impact on female and male migrant workers. We analyzes how this gendered impact is compounded by intersectionality that results in multiple inequalities shaping their work, identity, power relationship, agency, and family lives.
Method – Our analyses were primarily drawn from 14 surveys of major provinces with higher migration rates, and were supplemented by personal narratives and interviews of migrant workers.
Findings – The political-economic analysis of the world-system demonstrates how the intricate linkages among declines in trade, finance, and production led to the economic crisis in China, with more detrimental effects on women migrant workers than their male counterparts. The intersectionality of gender, class, age/generation, and regional differences has played out in the state-regulated process of migration, configuring and reconfiguring the organization of capital, labor, and production and determining unequal gender relations, class dynamics, citizenship, employment, and family life. Conditioned by complex inequalities, some affected migrant workers, far from being victimized, have demonstrated agency, resilience, and a spirit of resistance.
Research and practical implications – More disaggregated data by gender are needed to understand the full range of differential crisis effects on diverse women and men workers.
Originality/value of the study – This study suggests the importance of considering gender-sensitive policies and a gender mainstreaming approach to addressing gender inequality and improving migrant workers’ lives for their empowerment.
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Ling Zou and Chris Hunt
The purpose of this paper is to present a new test method (tape peel method) to evaluate conformal coating adhesion to electronic assemblies.
Abstract
Purpose
The purpose of this paper is to present a new test method (tape peel method) to evaluate conformal coating adhesion to electronic assemblies.
Design/methodology/approach
The key issue for this method is the low cohesive force of conformal coatings, and hence selection of a supporting material to peel the coating from the substrate is critical. A suitable cloth material (35 per cent cotton +75 per cent polyester with 20 per cent open area) has been selected as a peel tape, and achieved the best bonding with coatings, and the smallest affect on the coating curing process. Using the tape, the peel force of the coating from the electronic assembly, can be measured quantitatively, and hence the adhesion performance of the conformal coating assessed.
Findings
The method was validated using different coating types, substrate materials (bare laminate with and without resist, copper clad laminate, and contaminated laminate material), assemblies and components. The results demonstrated that the tape peel test is a sensitive method for measuring coating adhesion on different materials found on PCB assemblies. Coating adhesion was found not to be effected by a wide range flux residues, but components and some resists presented a far greater coating challenge, with some coatings achieving very low adhesion values.
Originality/value
This new method for evaluating conformal coating adhesion to electronic assemblies will be of benefit to coating developers and users, and help to minimise adhesion failures in service. The test has been demonstrated to be sensitive to a number of process and material variables.
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SIR testing is in practice carried out under a wider range of experimental conditions than those detailed in standards. The work presented here explores some of the issues when…
Abstract
SIR testing is in practice carried out under a wider range of experimental conditions than those detailed in standards. The work presented here explores some of the issues when using a range of fluxes with various processing conditions and also examines the influence of substrate finish, test bias and the reflow process. These results clearly show that care must be exercised when using different test set‐ups, and when extrapolating between testing and use conditions. In particular the use of a 50V test bias voltage can produce anomalous results when compared to a 5V use environment.
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The surface insulation resistance (SIR) test has traditionally been performed by taking measurements at certain points during a seven‐day test under well established environmental…
Abstract
The surface insulation resistance (SIR) test has traditionally been performed by taking measurements at certain points during a seven‐day test under well established environmental conditions. The work reported here explores the influence of test temperature and humidity when using a typical resin flux, a weak organic flux and glycol based fluxes when sampling SIR patterns every ten minutes. Results indicate that some fluxes are very sensitive to the test temperature, with volatilisation of flux residues an important issue. The frequent monitoring of the results also permitted the detection of dendrites during the SIR test. The results clearly show the importance of selecting the correct testing conditions and the benefit of frequent monitoring.
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Martin Wickham, Ling Zou and Christopher Hunt
As the transition away from lead‐containing solders gathers momentum, isotropic conducting adhesives (ICAs) are being considered as possible replacements for conventional SnPb…
Abstract
Purpose
As the transition away from lead‐containing solders gathers momentum, isotropic conducting adhesives (ICAs) are being considered as possible replacements for conventional SnPb solder in a range of applications. Consequently, the reliability of ICA joints is under scrutiny. The purpose of this paper is to report the effect of printed circuit board (PCB) and component finishes on the reliability of ICA joints.
Design/methodology/approach
Previous work by the authors identified a suitable test regime to generate relevant reliability data. In the present work, those tests are employed to investigate whether the finishes on the components and/or PCBs have any effect on the reliability of the ICA joints after exposure to damp heat conditions.
Findings
The effect of different finishes is found to be very adhesive material dependent. Two adhesives are studied, and for one material the joint reliability is relatively unaffected by changes in component or PCB surface finish. However, for the second material, and components with a high‐tin content‐plated finish, the joints display a less stable resistance. The surface finish on the PCB is found to have a smaller effect on joint reliability than the component finish, with results dependent on adhesive material type. Performance with one material exhibited little difference in reliability irrespective of the PCB surface finish. For the second material, the joint reliability performance with components having the electroless nickel/immersion gold finish, is not as good as that with components having the immersion tin or silver finishes.
Originality/value
The paper shows that surface finish is an important factor in determining the conductivity of ICA joints during exposure to the 85°C/85%RH environment. Systems containing tin are more prone to lose conductivity and, conversely, noble metal systems are more immune to degradation. This is a major concern as the industry is showing many signs that the component termination of choice will be pure tin.
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Ling Chunxian Zou and Chris Hunt
This paper aims to describe the development of an approach that uses a flexible substrate to investigate the mechanism of conductive anodic filament (CAF) growth and effect of…
Abstract
Purpose
This paper aims to describe the development of an approach that uses a flexible substrate to investigate the mechanism of conductive anodic filament (CAF) growth and effect of different material and manufacturing variables.
Design/methodology/approach
A new approach using a simulated test vehicle (STV) has been developed to study the CAF phenomena. The STV can be easily built under controlled conditions in the laboratory using different glass fibres and resin powder to investigate the effect of different variables separately on CAF. The advantage of the STV is that CAF can be formed in relatively short period in a controlled way, and CAF growth can be easily identified using a back-lighting under a microscope due to the thin flex material used as the test sample.
Findings
STV has been used to investigate a number of effects on CAF formation: different glass fibres, reflow process, acid contamination in drilled holes, desmear process and glass bundle size. The results demonstrate that for finished fibres acid contamination (plating solution) at the electrode was necessary for CAF formation. However, for unfinished glass fibres (loom state and heat cleaned) CAF can be formed without acid contamination. The reflow process significantly increases CAF formation. Running an aggressive desmear process and using large glass fibre bundle also increased CAF formation.
Originality/value
This new approach will be of benefit for printed circuit board (PCB) supplier to evaluate CAF performance on different resin systems and glass fibres to provide high CAF resistance quality PCBs. The test period (168 hours) would be much shorter than the traditional CAF testing (1,000 hours).
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Ling Chunxian Zou, Milos Dusek, Martin Wickham and Christopher Hunt
Enclosed print heads have recently been developed as an improvement on the traditional squeegee methods for solder paste printing. They offer the opportunity of widening the…
Abstract
Enclosed print heads have recently been developed as an improvement on the traditional squeegee methods for solder paste printing. They offer the opportunity of widening the printing process window and reducing process waste. Consequently, this work was undertaken to evaluate some aspects of enclosed print head printing, and it has been shown to be a robust process. A number of performance factors were established: with increased humidity the paste degradation was limited due to its sealed paste reservoir; the system also permitted successful intermittent printing over a 5 day period; printing is much more tolerant to distorted substrates than some squeegee blades, and hence improves printing on non‐planar surfaces; significant reduction in paste wastage occurs, since paste ageing is reduced.