Effect of current stressing on the reliability of 63Sn37Pb solder joints

The effect of current stressing on the reliability of 63Sn37Pb solder joints with Cu pads was investigated at temperatures of −5 °C and 125 °C up to 600 h. The samples were stressed with 3 A current (6.0 × 102 A/cm2 in the solder joint with diameter of 800 μm and 1.7 × 104 A/cm2 in the Cu trace with cross section area of 35 × 500 μm). The temperatures of the samples and interfacial reaction within the solder joints were examined. The microstructural change of the solder joints aged at 125 °C without current flow was also evaluated for comparison. It was confirmed that the current flow could cause the temperature of solder joints to rise rapidly and remarkably due to accumulation of massive Joule heat generated by the Cu trace. The solder joints stressed at 125 °C with 3 A current had an extensive growth of Cu6Sn5 and Cu3Sn intermetallic compounds (IMC) at both top and bottom solder-to-pad interfaces. It was a direct result of accelerated aging rather than an electromigration or thermomigration effect in this experiment. The kinetic is believed to be bulk diffusion controlled solid-state reaction, irrespective of the electron flow direction. When stressed at −5 °C with 3 A current, no significant change in microstructure and composition of the solder joints had occurred due to a very low diffusivity of the atoms as most Joule heat was eliminated at low temperature. The IMC evolution of the solder joints aged at 125 °C exhibited a subparabolic growth behavior, which is presumed to be a combined mechanism of grain boundary diffusion and bulk diffusion. This is mainly ascribed to the retardant effect against the diffusion course by the sufficiently thick IMC layer that was initially formed during the reflow soldering.

Horsham Properties Group Ltd v Clark: possession - mortgagee's right or discretionary remedy?

Comments on the Chancery Division decision in Horsham Properties Group Ltd v Clark on whether a mortgagee's exercise of its contractual right, on the mortgagor falling into arrears, to appoint receivers such that the property could be sold and possession obtained without triggering the court's discretionary powers pursuant to the Administration of Justice Act 1970 s.36 infringed the mortgagor's rights under the European Convention on Human Rights 1950 Protocol 1 art.1. Considers the implications of proposed reforms recasting the mortgagee's right to possession as a discretionary remedy. [From Legal Journals Index]

Art always at heart

The Art Workers Guild, brother body to the SPAB and once presided over by William Morris and his followers, is 125 years old this year. Alan Powers looks back over its history, and sheds light on the characters and common bonds between the two bodies – while present Brothers of the Guild are pictured at work by photographer Lara Platman for new book to mark the event.

'Marginal gothic': mediating the monstrous in British romanticism

In this paper I look at texts from the Romantic Period which strategically employ elements of the Gothic genre in what I describe as a `marginal` relationship with the Gothic canon. My intention is both to explore the way the boundaries of the genre might be extended, and to cast fresh light on some of the texts discussed, specifically in relation to the ways in which the `monstrous` is perceived and portrayed as villainy. In the first half of the paper, using Burke’s Philosophical Enquiry on the Sublime and the Beautiful as a starting point, I consider Burke’s Reflections on the Revolution in France, Godwin’s Caleb Williams, Radcliffe’s The Italian, and Blake’s The Marriage of Heaven and Hell as all in various ways examples of `marginal Gothic` that present evil doing as monstrous aberrations, also noting the contemporary reception of Beckford’s Vathek, praised in 1786 for its `accuracy and credibility`. In addition, I suggest that Wordsworth’s `Tintern Abbey` and Book VI of The Prelude provide evidence of marginal, but significant, Gothic influence that references Radcliffe’s and Burke’s explorations of a terror of the unknown. In the second half of the paper I focus on Scott’s Guy Mannering, or The Astrologer (1815) as an important example of a `marginal` Gothic novel. Scott’s reference to Vathek at a key point in his plot suggests that he had read Beckford’s novel as entirely `Gothic`. This discussion incorporates a comparison between Mannering’s youthful enthusiasm for astrological divination, and themes to be found in Shelley’s Frankenstein, notably with respect to the nature of Victor Frankenstein’s response to `old` and `new` science and medicine, and to the creation and control of Gothic monstrosity. In these and in other instances, it will be argued that the `marginal Gothic` of Scott’s novel may be read as a precursor to Shelley’s work. [From the Author]

A genetic marker to separate Emiliania huxleyi (Prymnesiophyceae) morphotypes

Emiliania huxleyi (Lohm.) Hay and Mohler is a ubiquitous unicellular marine alga surrounded by an elaborate covering of calcite platelets called coccoliths. It is an important primary producer involved in oceanic biogeochemistry and climate regulation. Currently, E. huxleyi is separated into five morphotypes based on morphometric, physiological, biochemical, and immunological differences. However, a genetic marker has yet to be found to characterize these morphotypes. With the use of sequence analysis and denaturing gradient gel electrophoresis, we discovered a genetic marker that correlates significantly with the separation of the most widely recognized A and B morphotypes. Furthermore, we reveal that the A morphotype is composed of a number of distinct genotypes. This marker lies within the 3' untranslated region of a coccolith associated protein mRNA, which is implicated in regulating coccolith calcification. Consequently, we tentatively termed this marker the coccolith morphology motif.

Interregional Biological Responses in the North Atlantic to Hydrometeorological Forcing

Using data from the CPR survey seven case studies are described that document different spatial and temporal responses in the plankton to hydroclimatic events. Long-term trends in the plankton of the eastern Atlantic and the North Sea over the last five decades are examined. Two of the examples revisit correlations that have been described between copepod abundance in the eastern Atlantic and North Sea and indices of atmospheric variability, the North Atlantic Oscillation index and the Gulf Stream North Wall index. Evidence for an increase in levels of Phytoplankton Colour (a visual index of chlorophyll) on the eastern and western sides of the Atlantic is presented. Changes in three trophic levels and in the hydrodynamics and chemistry of the North Sea circa 1988 are outlined as a regime shift. Two of the case studies emphasise the importance of variability in oceanic advection into shelf seas and the role of western and eastern margin currents at the shelf edge. The plankton appear to be integrating hydrometeorological signals and reflecting basin scale changes in circulation of surface, intermediate and deep waters in part associated with the NAO. The extent to which climatic variability may be contributing to the observed changes in the plankton is discussed with a forecast of potential future ecosystem effects in a climate change scenario.

Identification of a diagnostic marker to detect freshwater cyanophages of filamentous cyanobacteria

Cyanophages are viruses that infect the cyanobacteria, globally important photosynthetic microorganisms. Cyanophages are considered significant components of microbial communities, playing major roles in influencing host community diversity and primary productivity, terminating cyanobacterial water blooms, and influencing biogeochemical cycles. Cyanophages are ubiquitous in both marine and freshwater systems; however, the majority of molecular research has been biased toward the study of marine cyanophages. In this study, a diagnostic probe was developed to detect freshwater cyanophages in natural waters. Oligonucleotide PCR-based primers were designed to specifically amplify the major capsid protein gene from previously characterized freshwater cyanomyoviruses that are infectious to the filamentous, nitrogen-fixing cyanobacterial genera Anabaena and Nostoc. The primers were also successful in yielding PCR products from mixed virus communities concentrated from water samples collected from freshwater lakes in the United Kingdom. The probes are thought to provide a useful tool for the investigation of cyanophage diversity in freshwater environments.