Modeling the effect of lead-free soldering on flexible substrates

Flexible Circuit Boards (FPCs) are now being widely used in the electronic industries especially in the areas of electronic packages. Due to European lead-free legislation which has been implemented since July 2006, electronic packaging industries have to switch to use in the lead-free soldering technology. This change has posed a number of challenges in terms of development of lead-free solders and compatible substrates. An increase of at least 20-50 degrees in the reflow temperature is a concern and substantial research is required to investigate a sustainable design of flexible circuit boards as carrier substrates. This paper investigates a number of design variables such as copper conductor width, type of substrate materials, effect of insulating materials, etc. Computer modeling has been used to investigate thermo-mechanical behavior, and reliability, of flexible substrates after they have been subjected to a lead- free solder processing. Results will show particular designs that behave better for a particular rise in peak reflow temperature. Also presented will be the types of failures that can occur in these substrates and what particular materials are more reliable.

SWITCH city facilitated progress analysis: Cali

This report aims at providing an evaluation of the Learning Alliance (LA) process in Cali, Colombia, after 17 months from its inception. In fact, Cali has become a SWITCH demonstration city only at the beginning of 2008. Until then, Cali had only been a SWITCH case study. The establishment of the LA started de facto in April 2007. The relative magnitude of the impact achieved so far by the local LA has to be seen in the light of its limited duration.