Megasonic agitation for enhanced electrodeposition of copper

In this paper we propose an agitation method based on megasonic acoustic streaming to overcome the limitations in plating rate and uniformity of the metal deposits during the electroplating process. Megasonic agitation at a frequency of 1 MHz allows the reduction of the thickness of the Nernst diffusion layer to less than 600 nm. Two applications that demonstrate the benefits of megasonic acoustic streaming are presented: the formation of uniform ultra-fine pitch flip-chip bumps and the metallisation of high aspect ratio microvias. For the latter application, a multi-physics based numerical simulation is implemented to describe the hydrodynamics introduced by the acoustic waves as they travel inside the deep microvias.

The interaction of polyacid-modified composite resins ("compomers") with aqueous fluoride solutions

OBJECTIVE: The aim of this study was to investigate how the release of fluoride from two compomers and a fluoridated composite resin was affected by exposure to KF solution. MATERIAL AND METHODS: Two compomers (Dyract AP and Compoglass F) and one fluoridated composite (Wave) were prepared as discs (6 mm diameter and 2 mm thick), curing with a standard dental lamp. They were then stored in either water or 0.5% KF for 1 week, followed by placement in water for periods of 1 week up to 5 weeks total. Fluoride was determined with and without TISAB (to allow complexed and decomplexed fluoride to be determined), and other ion release (Na, Ca, Al, Si, P) was determined by ICP-OES. RESULTS: Specimens were found not to take up fluoride from 100 ppm KF solution in 24 h, but to release additional fluoride when stored for up to five weeks. Compomers released more fluoride cumulatively following exposure to KF solution (p<0.001), all of which was decomplexed, though initial (1 week) values were not statistically significant for Dyract AP. Other ions showed no variations in release over 1 week, regardless of whether the specimens were exposed to KF. Unlike the compomers, Wave showed no change in fluoride release as a result of exposure to KF. CONCLUSIONS: Compomers are affected by KF solution, and release more fluoride (but not other ions) after exposure than if stored in water.

Public sector pay in the UK: has the historic pattern of public/private sector pay movements been broken?

The historic pattern of public sector pay movements in the UK has been counter-cyclical with private sector pay growth. Periods of relative decline in public sector pay against private sector movements have been followed by periods of ‘catch-up’ as Government controls are eased to remedy skill shortages or deal with industrial unrest among public servants. Public sector ‘catch up’ increases have therefore come at awkward times for Government, often coinciding with economic downturn in the private sector (Trinder 1994, White 1996, Bach 2002). Several such epochs of public sector pay policy can be identified since the 1970s. The question is whether the current limits on public sector pay being imposed by the UK Government fit this historic pattern or whether the pattern has been broken and, if so, how and why? This paper takes a historical approach in considering the context to public sector pay determination in the UK. In particular the paper seeks to review the period since Labour came into office (White and Hatchett 2003) and the various pay ‘modernisation’ exercises that have been in process over the last decade (White 2004). The paper draws on national statistics on public sector employment and pay levels to chart changes in public sector pay policy and draws on secondary literature to consider both Government policy intentions and the impact of these policies for public servants.