A reflow soldering retro-design system for rework station based on Q-factor

Abstract

Currently reflow soldering is the primary process used for the assembly of PCB. We now have finite difference (FD) and computational fluid dynamics (CFD) modeling tools, which can establish the reflow soldering process models and compute out the detailed representations of the real reflow ovens. This paper presents the development of a reflow soldering retro-design system for rework stations with the above modeling tools. Heating factor (Q-factor) is used to evaluate whether the achieved profile fulfils the soldering task well despite the real curve different from the ideal one. The behavior of adjusting the heat profile to make the feature points meet the requirements of components and solders computationally may then get the optimal profile without any actual reflow running. Meanwhile, the system introduces the closed-loop implementation of process recipe on the device controller so as to enhance the execution repeatability. This system is used to set the bottom and top heater profiles of a Metcal APR-5000 rework station.