"I'm having a little trouble believing you unless by "rework" you meant "reflow"." Nope, we don't use flux at all for rework. As the majority of our boards are

"I'm having a little trouble believing you unless by "rework" you meant "reflow"." Nope, we don't use flux at all for rework. As the majority of our boards are solid metal, we just slap them on a heater and poke the components down or slide them into place. Flux isn't needed. Even with crappy RoHS tin solder. If you're getting significant-enough oxidation that interferes with rework with the product fresh out of the oven, or even a day or two later, you're doing something extremely wrong. Check and make sure your production paste isn't contaminated.