Novel approach to reflow oven design to control and optimise lead free soldering process

Much research has been carried out to understand the impact of lead-free soldering on electronics manufacture. The magnitude of the impact extends to the business, mechanics, product and processes supported by companies. Surveys have showed that most companies may be able to cope with the new legislation if they can meet the cost of process changes and capital investments required for the new facilities and the knowledge required. The main influenced areas are the soldering process using the conventional ovens, maintaining quality of solders and achieving flexible production. Researchers at Loughborough University have been investigating an innovative soldering oven that not only eliminates the high investment cost of existing reflow ovens, but it can also improve the productivity of the production line by providing the ability to solder smaller and more variable batch size and types. The new oven has ability to control temperature accurately in an enclosed chamber. The oven is also capable of applying inert gas for rapid cooling down of products. In this paper, a set of laboratory experiments are described that examine the microstructure and the quality of solders in such ovens by testing heating profiles, heating times, cooling rates, and ageing processes. The authors conclude by proposing a set of recommendations for soldering profiles, materials and cooling rates to be used for lead-free soldering that adopted by the new oven