The production of lead-free solder spheres for the electronics industry using materials jetting

This thesis describes an investigation into the production of precision dimension lead-free solder spheres using continuous-mode jetting equipment for the electronics manufacturing industry. The "Jetting Technology" has evolved from the ink-jet printing industry and has been adapted to cope with elevated material temperatures, which allow for a much wider range of materials to be investigated. A continuous-mode jetting head was licensed from the Massachusetts Institute of Technology and re-engineered to produce uniform solder droplets between 54–1152 μm diameter (± 5 μm tolerance), at operating temperatures up to 400°C. The necessary modifications to the MIT equipment to facilitate the research have been fully documented and include: orifice redesign; combined focusing and deflection hardware; 'in-situ' stream direction adjustment; droplet detection and the development of a novel algorithm to precisely control the size of the droplets. [Continues.]