Effect of adding 0.3wt% Ni into the Sn-0.7wt% Cu solder - Part II: Growth of intermetallic layer with Cu during wetting and aging

The growth behavior of intermetallic layer with or without adding 0.3 wt% Ni into the Sn-0.7Cu solder was studied during the wetting reaction on Cu-substrate and thereafter in solid-state aging condition. The Cu-solder reaction couple was prepared at 255, 275 and 295 °C for 10 s. The samples reacted at 255 °C were then isothermally aged for 2-14 days at 150 °C. The reaction species formed for the Sn-0.7Cu/Cu and Sn-0.7Cu-0.3Ni/Cu soldering systems were Cu6Sn5 and (CuNi)6Sn5, respectively. The thickness of the intermetallic compounds formed at the solder/Cu interfaces and also in the bulk of both solders increased with the increase of reaction temperature. It was found that Ni-containing Sn-0.7Cu solder exhibited lower growth of intermetallic layer during wetting and in the early stage of aging and eventually exceeded the intermetallic layer thickness of Sn-0.7Cu/Cu soldering system after 6 days of aging. As the aging time proceeds, a non-uniform intermetallic layer growth tendency was observed for the case of Sn-0.7Cu-0.3Ni solder. The growth behavior of intermetallic layer during aging for both solders followed the diffusion-controlled mechanism. The intermetallic layer growth rate constants for Sn-0.7Cu and Sn-0.7Cu-0.3Ni solders were calculated as 1.41 × 10-17 and 1.89 × 10-17 m2/s, respectively which indicated that adding 0.3 wt% Ni with Sn-0.7Cu solder contributed to the higher growth of intermetallic layer during aging. © 2006 Elsevier B.V. All rights reserved.

The creative masses of digital Britain

The present recession has prompted scholarly and journalistic questioning of the contributions of the cultural industries to the economy. The talent-rich metropolitan clusters of London and New York are well-placed to ride out a thoroughgoing shakeup of the media markets if they manage their infrastructure, space and resources strategically, as Richard Florida has recently argued. This seems to be the assumption behind the recent Digital Britain interim report, and Gordon Brown's remarks that a digital revolution "lies at the heart" of Britain's economic recovery and that broadband and the media industry can play a leading role in pulling the UK out of the recession. Focusing on the Digital Britain report and consultation documents, this presentation seeks to unpack some of the fundamental assumptions behind this link between digital infrastructure, creativity and profitability. In particular the implicit notion of an engaged audience of users, generating "content" as well as shaping new media platforms calls into question long-held theoretical constructions of the mass audience of consumers as spectators; instead, the audience emerges as a potential economic powerhouse, an underused resource for tomorrow's cultural industries.

Creative leadership & communities of practice

This Second Wave presentation focused on 'Creative Leadership and Communities of Practice', with particular reference to issues of trust affecting young people, unemployment and wider uncertainties in an economic recession when people were facing job cuts and in a social environment characterised by cynicism and a downturn in trust. Young people who join Second Wave are brought into a community of practice (CoP) (Lave and Wenger, 1991; Wenger, 1999) involving a dynamic, fluid process which is distinctive in its transformative power to change people's lives. The philosophy behind this involves Dewey's notion of the 'active self' (Dewey, 1916) and the theories of 'social constructivism' (Vygotsky, 1978). The process fosters trust, confidence and social learning (Bandura, 1977; Vygotsky, 1978) in which young people join in with a dialogue involving participation in the youth-centred creative space. The 'border zone' (Heath, 1994) in that creative space enables young people to connect with each other in the specialist field of youth arts. The youth-centred partnerships involved lead to greater confidence and development in a range of important artistic, social, cognitive and emotional skills and opportunities. Ultimately, the young person may become engaged in multi-agency working with Second Wave's external partners. Throughout all of these processes, young people are encouraged progressively to develop a more 'active self' to engage proactively with many different beneficial opportunities relating to the performing arts. In an era in which there has been a loss of trust in public life this is particularly important. If trust is defined in part as a belief in the honesty, competence and benevolence of others, it tends to act like 'social glue', cushioning difficult situations and enabling actions to take place easily that otherwise would not be permissible. The Edelman Trust Barometer for 2009 has recorded a marked diminution of trust in corporations, businesses and government, as a result of the credit crunch. While the US and parts of Europe were showing recovery from a generalised loss of trust by mid-year 2009, the UK had not. Social attitudes in Britain may be hardening - from being a nation of sceptics we may be becoming a nation of cynics: for example, only 13% of the population surveyed by Edelman trust politicians to tell the truth. In this situation, there is a need to promote positive measures to build trust. The presentation aims described key aspects of Second Wave's approach to identify and disseminate its model of good practice to make this more explicit and accessible to others. It is with awareness of the profoundly challenging circumstances facing young people, particularly but not exclusively in inner city urban areas such as Deptford, and the valuable contribution youth arts work can make to their well-being and development, that the presentation was carried out. In an era of generalised mistrust, the work done at Second Wave is crucial in empowering and supporting young people to find a positive and creative direction as part of the community.

Effect of long-term aging on the rheological characteristics and printing performance of lead-free solder pastes used for flip-chip assembly

Stencil printing of solder pastes is a critical stage in the SMT assembly process as a high proportion of the solder-related defects can be attributed to this stage. As the trend towards product miniaturization continues, there is a greater need for better understanding of the rheological behaviour and printing performance of new paste formulations. This fundamental understanding is crucial for achieving the repeatable solder paste deposits from board-to-board and pad-to-pad required for more reliable solder interconnections. The paper concerns a study on the effect of ageing on the rheological characteristics and printing performance of new lead-free solder pastes formulations used for flip-chip assembly applications. The objective is to correlate the rheological characteristics of aged paste samples to their printing performance. The methodology developed can be used for bench-marking new lead-free paste formulations in terms of shelf life, the potential deterioration in rheological characteristics and their printing performance.

Creative environments for art, craft & design teaching in the 21st century

This booklet has been designed for student teachers in particular and those in their early years as teachers of art, craft and design. It is suitable however for all teachers of art and design, and will be useful when considering the 2007 review of the Art and Design programme of study (POS) with its focus on creativity and ideas developments. The contents are intended as prompts or guides and ideas for initiating individual responses to themes or projects and a "way in" for the teacher when guiding pupils. It explains in detail how one might inspire all groups with appropriate and varied resources.