We use hot air leveling (HAL) process in pcb production. HAL process is 3 steps. �n 1. step flux. 2. step is HAL. And 3. step is rinsing. As you know there is mustn't any flux after rinsing operation. Our flux chemical is water soluable. But there are flux residue on some pcbs after rinsing. What's your suggestion? Using a brush during rinsing. or put some cleaner in rinse water. Another thing that we maybe use cleaner after HAL. I mean we should put all soldered plates in cleaner soluation in a container and wait for a while before rinsing operation.