Spray fluxing during wave soldering for the no-clean process is a major challenge. To achieve high yield and minimize flux contamination requires good process control. To attain satisJactory topside solder fill of pin-through holes (PTHs), both flux deposition and penetration must be well controlled in the process. In this paper, a design of experiment (DOE) approach to optimize the process is presented. Three critical process variables impacting flux deposition and penetration responses were measured. They were flux tank pressure, nozzle traversing speed and conveyor speed. Using the parameter settings suggested by the DOE analysis, the flux penetration to PTHs is optimized to obtain satisfactory topside solder fill. At the same time with precise control of flux deposition, the flux residue left on the board is minimized. The importance of flux deposition uniformity and repeatability for, the no-clean process is also discussed.
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