[BSHM meetings] Topics in the history of financial mathematics: early commerce to chaos in modern stock markets

This account provides an overview of the study day, entitled 'Topics in the History of Financial Mathematics: Early commerce to chaos in modern stock markets,' held by the British Society for the History of Mathematics jointly with Gresham College, at Gresham College, London on 25th April 2008. The series of talks explored the development of mathematics and mathematical techniques in a commercial and financial context.

Performance and reliability of flexible substrates when subjected to lead-free processing

The use of flexible substrates is growing in many applications such as computer peripherals, hand held devices, telecommunications, automotive, aerospace, etc. The drive to adopt flexible circuits is due to their ability to reduce size, weight, assembly time and cost of the final product.They also accommodate flexibility by allowing relative movement between component parts and provide a route for three dimensional packaging. This paper will describe some of the current research results from the Flex-No-Lead project, a European Commission sponsored research program. The principle aim of this project is to investigate the processing, performance, and reliability of flexible substrates when subjected to new environmentally friendly, lead-free soldering technologies. This paper will discuss the impact of specific design variables on performance and reliability. In particular the paper will focus on copper track designs, substrate material, dielectric material and solder-mask defined joints.