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A clear industry trend now spreading beyond the traditional North American and European markets is characterized by short production runs and frequent production line changeover. Improved technologies for line balancing, production planning, smart feeders, MES and more are being used more effectively to allow for faster production line changeover and less downtime. One obstacle tends to be the reflow oven. Having a $2 million production line sitting for 30+ minutes while waiting for a $40,000+ oven to stabilize on a new recipe will wreak havoc on profits. The goal should be instant oven changeover, and that goal is achievable in the majority of applications.
First, a few observations on the purpose of a reflow oven. I always ask process engineers the following question: What is the main job performed by the reflow oven? The answers tend to be to melt solder, solder the components onto the board and create a strong solder joint. All of that is true, but there is more to it. Clearly, we do not want a strong solder joint that cracked the component in order to achieve it. So the reflow oven needs to solder the assembly within the tolerances/process window set by the relevant solder paste, components and substrate.
Editor's Note: This article originally appeared in the March 2016 issue of SMT Magazine.