Effects of thermal cycling profiles on the performance of chip-on-flex assembly using anisotropic conductive films

Anisotropic conductive films (ACFs) are widely used in the electronic packaging industries because of their fine pitch potential and the assembly process is simpler compared to the soldering process. However, there are still unsolved issues in the volume productions using ACFs. The main reason is that the effects of many factors on the interconnects are not well understood. This work focuses on the performance of ACF-bonded chip-on-flex assemblies subjected to a range of thermal cycling test conditions. Both experimental and three-dimensional finite element computer modelling methods are used. It has been revealed that greater temperature ranges and longer dwell-times give rise to higher stresses in the ACF interconnects. Higher stresses are concentrated along the edges of the chip-ACF interfaces. In the experiments, the results show that higher temperature ranges and prolonged dwell times increase contact resistance values. Close examination of the microstructures along the bond-line through the scanning electron microscope (SEM) indicates that cyclic thermal loads disjoint the conductive particles from the bump of the chip and/or pad of the substrate and this is thought to be related to the increase of the contact resistance value and the failure of the ACF joints.

Review of methods to predict solder joint reliability under thermo-mechanical cycling

Solder joints are often the cause of failure in electronic devices, failing due to cyclic creep induced ductile fatigue. This paper will review the modelling methods available to predict the lifetime of SnPb and SnAgCu solder joints under thermo-mechanical cycling conditions such as power cycling, accelerated thermal cycling and isothermal testing, the methods do not apply to other damage mechanisms such as vibration or drop-testing. Analytical methods such as recommended by the IPC are covered, which are simple to use but limited in capability. Finite element modelling methods are reviewed, along with the necessary constitutive laws and fatigue laws for solder, these offer the most accurate predictions at the current time. Research on state-of-the-art damage mechanics methods is also presented, although these have not undergone enough experimental validation to be recommended at present

Influence of a fed or fasted state on the s-IgA response to prolonged cycling in active men and women

This study investigated the effect of a fed or fasted state on the salivary immunoglobulin A (s-IgA) response to prolonged cycling. Using a randomized, crossover design, 16 active adults (8 men and 8 women) performed 2 hr of cycling on a stationary ergometer at 65% of maximal oxygen uptake on 1 occasion after an overnight fast (FAST) and on another occasion 2 hr after consuming a 2.2-MJ high-carbohydrate meal (FED). Timed, unstimulated whole saliva samples were collected immediately before ingestion of the meal, immediately preexercise, 5 min before cessation of exercise, immediately postexercise, and 1 hr postexercise. The samples were analyzed for s-IgA concentration, osmolality, and cortisol, and saliva flow rates were determined to calculate s-IgA secretion rate. Saliva flow rate decreased by 50% during exercise (p < .05), and s-IgA concentration increased by 42% (p < .05), but s-IgA secretion rate remained unchanged. There was a 37% reduction in s-IgA:osmolality postexercise (p < .05), and salivary cortisol increased by 68% (p < .05). There was no effect of FED vs. FAST on these salivary responses. The s-IgA concentration, secretion rate, and osmolality were found to be significantly lower in women than in men throughout the exercise protocol (p < .05); however, there was no difference between genders in saliva flow rate, s-IgA:osmolality ratio, or cortisol. These data demonstrate that a fed or fasted state 2 hr before exercise does not influence resting s-IgA or the response to prolonged cycling. Furthermore, these results show lower levels of s-IgA and osmolality in women than in men at rest.

The interprofessional practitioner: changing professional identity in social work

Twenty years ago the first joint training programme in learning disability nursing and social work was established as a collaborative project to develop practitioners able to work holistically with people with learning disabilities. Since then a number of programmes have continued this work and more recently the approach has developed in the mental health specialism. These programmes have changed the nature of singular social work education and created a new region of knowledge (Bernstein, 2000) for those who have experienced them. What began as a radical experiment in interprofessional education has been sustained by a strong commitment to the belief that the practitioners who qualify from such programmes are well equipped to support people with learning disabilities in changing and multi-professional services. As with much interprofessional education, however, there is an ongoing need to build an evidence base linking such education with successful outcomes in practice. This paper presents and explores the outcomes of a doctoral research study aimed at evaluating the impact of joint training in learning disability nursing and social work on the professional identity, skills and working practices of practitioners who undertook it. The research was undertaken with almost fifty jointly trained practitioners and involved a national survey followed by semi-structured interviews. The results suggest that practitioners who experience the dual socialisation inherent in this type of training found both gains and losses in the process. They appear to emerge, however, with a confidence, resilience and breadth of knowledge which were part of the early vision for this transformative approach to professional training. Bernstein B. (2000). Pedagogy, Symbolic Control and Identity. Theory, Research, Critique. Revised Edition. Lanham: Rowman and Littlefield (USA).

Absence makes the professional try harder? Meeting the needs of socially excluded young men who become fathers

Research on socially excluded young fathers has been minimally addressed in the literature (SEU 1999, 2004). Indeed, research on young parents which informs health and social care professionals is often presented ‘through the eyes of the mother’ (Reeves 2006). Young parents in general and young fathers in particular are notoriously difficult to gain access to and engage with (Tyrer et al 2005) particularly if they have had previous negative involvement with the statutory services. Moreover, as Daniel and Taylor (1999, 2001, 2003) point out, professionals working in the health and care services often have an intense ‘maternal’ focus and this often excludes fathers from discussion and decisions about their children. The focus of this paper, drawing on two narrative studies of young fathers aged between 15-24 from the US and USA, is to evaluate the features of professional relationships that young fathers describe as finding helpful. Indeed, the findings discuss moving away from a culture of parenting classes, which all the young men interviewed described as finding problematical and in some cases embarrassing, to a culture of support which actively draws on their strengths and helps them become providers for their new families.

Continuing Professional Development: rhetoric and practice in the NHS

This article explores the experience of Continuing Professional Development (CPD) by supervisory-level clinical staff in the National Health Service. Four main themes are highlighted in the literature, namely the nature and experience of CPD, its relationship with human resource management practices and in particular in career development and planning. These themes are examined utilising sources of (triangulated) empirical data based on a 2500 sample survey conducted across five NHS Trusts. A key finding was that responsibility for learning and development was perceived as belonging to the individual rather than the organisation. Other findings concern a lack of resource-based commitment by the organisation to CPD for clinical staff undertaking supervisory-level roles and evidence of 'credentialism' with its emphasis on seeking certificated qualifications. The findings raise concerns about the potential for clinical staff to become disillusioned and to perceive a potential breach in their psychological contract because of problems in reconciling their own interests with those of their professional body, and that of their employer in relation to CPD.