Motohiro Yamane, Nobuaki Orita, Koichi Miyazaki and Weiming Zhou
The main issue with regard to improving the heating ability of reflow ovens is to minimize the temperature difference ΔT among the various parts of the printed circuit board (PCB) during the reflow soldering process. We need to control temperature within a much narrower process margin when we use lead-free soldering. Accordingly, our development target in this work is to achieve a significant increase in heat transfer coefficient α , fundamental to the heating performance of a reflow oven. We have developed a new model of reflow oven for lead-free soldering with a much higher heating ability by redesigning the hot air blowing unit, specifically by changing the design of the hot air panel. We were able to achieve this target in only five months by using process diagnostic techniques such as direct measurement of heat transfer coefficient and flow visualization, which we have developed and used for various applications.