Correlation of solder paste rheology with computational simulations of the stencil printing process

Soldering technologies continue to evolve to meet the demands of the continuous miniaturisation of electronic products, particularly in the area of solder paste formulations used in the reflow soldering of surface mount devices. Stencil printing continues to be a leading process used for the deposition of solder paste onto printed circuit boards (PCBs) in the volume production of electronic assemblies, despite problems in achieving a consistent print quality at an ultra-fine pitch. In order to eliminate these defects a good understanding of the processes involved in printing is important. Computational simulations may complement experimental print trials and paste characterisation studies, and provide an extra dimension to the understanding of the process. The characteristics and flow properties of solder pastes depend primarily on their chemical and physical composition and good material property data is essential for meaningful results to be obtained by computational simulation.This paper describes paste characterisation and computational simulation studies that have been undertaken through the collaboration of the School of Aeronautical, Mechanical and Manufacturing Engineering at Salford University and the Centre for Numerical Modelling and Process Analysis at the University of Greenwich. The rheological profile of two different paste formulations (lead and lead-free) for sub 100 micron flip-chip devices are tested and applied to computational simulations of their flow behaviour during the printing process.

What Education Studies is and what it might be

Education Studies at the University of Greenwich is presented as an example of what Education Studies is – at least at one Higher Education Institution. As a field of practice to which a body of knowledge can be applied, Education Studies shares common features with other disciplinary fields of study. It is also unique in that its field – learning, is also what its students do – learn. What Education Studies isn’t is then discussed in relation to studies of schooling, the psychology of learning, sociology of education, traditional education degrees and teacher training. Lastly, what Education Studies could become is presented with reference to Ranson’s (1993) argument for the centrality of education as the common focus of all HE study. It is suggested that the subject could then contribute to expanding critical space in (higher) education through making research/ scholarship and creation an integral part of the Independent Study of all students at all levels of learning. This would be a necessary complement to the wider democratic transformation now demanded for human survival. It would also accord with what Marx called humanity’s “species being” as a “learning animal” (Morris). Such a social theory of learning can discriminate between information and competence at one level of learning and (corresponding terms) knowledge and skill at another more generalised level in relation to new divisions of knowledge and labour. Potentially these levels can be combined to create a new form of polytechnic learning, relating theory to practice, education to training and further to higher education.